Download - Final Report
UNDUCTED FAN ENGINE DESIGN
Embry-Riddle Aeronautical University
AE-440
Dr. Magdy Attia
04.26.2011
TEAM FUDD
Chris Burch
Helena Hobbs
Noelle Palmer
Ryan Dantis
Shaheryar Khan
Steven Bohlemann
Timothy Hauenstein
2
Executive Summary
This report covers the detailed analysis for the unducted propfan engine with variable pitch and counter
rotating blades to compete in the same thrust class as the CFM International CFM 56-7B24. The design
uses 13 blades for the forward propfan and 11 blades for the aft propfan and has a diameter of 4.04m.
Propfan 1 runs at 1708 RPM and propfan 2 runs at 1855 RPM at cruise conditions. At takeoff conditions,
propfan 1 and 2 operate at 1610 RPM. The variable pitch blades remove the need for thrust reversers
and save a large amount of weight compared to conventional turbofan configurations. The engine is
designed to cruise at .85M at 34,000ft altitude. Takeoff speed was assumed to be .212M. The engine
can produce the required 7402lbf of thrust, which amounts 40% of CFM56 7B24 takeoff thrust. The
cruise TSFC is 0.63 per hour which is comparable to .627 of the CFM56. The TIT is 1558K for cruise and
1672K for takeoff. The exhaust gas temperature (EGT) is 681.4K for cruise and 832.2K for takeoff. Core
mass flow is designed for a cruise value of 30kg/s at cruise and 65kg/s at takeoff. The first and second
propfan mass flows are 456.1 and 459.8 respectively at cruise. At takeoff the propfan mass flows change
to 164.2 for the first propfan then 219.0 for the second propfan.
3
Table of Contents
1. Introduction and Competitive Analysis ............................................................................................... 14
1.1 Problem Statement and Requirements ...................................................................................... 14
1.2 Detailed Analysis ......................................................................................................................... 15
1.3 Technological Innovations .......................................................................................................... 16
2. Cycle .................................................................................................................................................... 17
2.1 General Information ................................................................................................................... 17
2.2 Cycle at Design: Cruise ................................................................................................................ 18
2.3 Cycle at off-design: Take-off ....................................................................................................... 20
2.4 Key Engine Performance Values ................................................................................................. 22
2.5 Customer and Cooling Bleeds ..................................................................................................... 22
3. Intermediate Pressure Compressor (IPC) ........................................................................................... 23
3.1 IPC at Design Condition: Cruise ................................................................................................... 23
3.1.1 Key IPC design choices and criteria ..................................................................................... 24
3.1.2 Aerodynamic Analysis ......................................................................................................... 25
3.1.3 Thermodynamic analysis ..................................................................................................... 29
3.1.4 Geometric Analysis ............................................................................................................. 30
3.2 Off Design Condition: Takeoff ..................................................................................................... 33
3.2.1 IPC design criteria ............................................................................................................... 33
3.2.2 Geometry Analysis .............................................................................................................. 34
3.2.3 Key IPC trends ..................................................................................................................... 36
4. High Pressure Compressor (HPC) ........................................................................................................ 39
4.1 HPC at Design Conditions: Cruise ................................................................................................ 39
4.1.1 Aerodynamic Analysis ......................................................................................................... 39
4.1.2 Thermodynamic Analysis .................................................................................................... 45
4.1.3 Geometric Analysis ............................................................................................................. 46
4.2 HPC at Off Design Conditions: Takeoff ........................................................................................ 48
4.2.1 HPC Design Criteria ............................................................................................................. 48
4.2.2 Geometric Analysis ............................................................................................................. 49
4.2.3 Key HPC Trends ................................................................................................................... 51
5. Combustion Chamber ......................................................................................................................... 53
6. High Pressure Turbine (HPT) ............................................................................................................... 56
4
6.1 Aerodynamic Analysis ................................................................................................................. 57
6.2 Thermodynamic Analysis ............................................................................................................ 60
6.3 Geometric Analysis ..................................................................................................................... 61
7. Intermediate Pressure Turbine (IPT) ................................................................................................... 64
7.1 Aerodynamic Analysis ................................................................................................................. 65
7.2 Thermodynamic Analysis ............................................................................................................ 70
7.3 Geometric Analysis ..................................................................................................................... 71
8. Power Turbine (PT) ............................................................................................................................. 74
8.1 Aerodynamic Analysis ................................................................................................................. 77
8.2 Thermodynamic Analysis ............................................................................................................ 83
8.3 Geometric Analysis ..................................................................................................................... 87
9. Propfan ................................................................................................................................................ 90
9.1. Geometric Analysis ..................................................................................................................... 91
9.2. Aerodynamic Analysis ................................................................................................................. 97
9.3. Thermodynamic Analysis ............................................................................................................ 99
9.4. Performance ............................................................................................................................. 103
10. Inlet ................................................................................................................................................... 105
11. Ducts ................................................................................................................................................. 108
11.1 High Pressure Compressor Exit Diffuser ................................................................................... 108
11.1.1 Diffuser Thermodynamics ................................................................................................. 108
11.1.2 Diffuser Geometry ............................................................................................................ 109
11.2 Intermediate Pressure Compressor/Power Turbine Duct ........................................................ 109
11.2.1 Duct Thermodynamics ...................................................................................................... 109
11.2.2 Duct Geometry .................................................................................................................. 110
12. Materials ........................................................................................................................................... 111
12.1 Prop Fan .................................................................................................................................... 111
12.2 Compressor ............................................................................................................................... 112
12.3 Combustion Chamber ............................................................................................................... 112
12.3.1 Thermal Barrier Coating (TBC) .......................................................................................... 113
12.3.2 Anti Oxidation Coating ...................................................................................................... 114
12.4 Turbine ...................................................................................................................................... 114
12.5 Duct and Diffuser ...................................................................................................................... 115
5
12.6 Inlet and Exit Cone .................................................................................................................... 116
1. References ........................................................................................................................................ 117
2. Appendix ........................................................................................................................................... 118
6
Table of Figures
Figure 1: Unducted Propfan GE36 (NASA) .................................................................................................. 16
Figure 2: Total and Static Pressure for cruise conditions............................................................................ 18
Figure 3: Total and Static Temperature for Cruise Conditions ................................................................... 19
Figure 4: Mach Number Trend at Cruise ..................................................................................................... 19
Figure 5: Total and Static Pressure for Takeoff Conditions......................................................................... 20
Figure 6: Total and Static Temperature for Takeoff Conditions ................................................................. 21
Figure 7: Mach number Trend at Take-Off ................................................................................................. 21
Figure 8: IPC Isometric View ....................................................................................................................... 23
Figure 9: IPC Velocity Triangles at the Tip of the Second Stage.................................................................. 26
Figure 10: IPC Velocity Triangle at the Mid of the Second Stage ................................................................ 27
Figure 11: IPC Velocity Triangle at the Hub of Second Stage ...................................................................... 28
Figure 12: IPC h-s Diagram of the Second Stage in the absolute FoR ......................................................... 29
Figure 13: IPC Meridional View ................................................................................................................... 30
Figure 14: IPC Stagger ................................................................................................................................. 31
Figure 15: IPC Gap to Pitch Ratio ................................................................................................................ 32
Figure 16: IPC Number of Blades vs Stages ................................................................................................. 32
Figure 17: GE90-76B RPM at Take-Off and Cruise Conditions .................................................................... 35
Figure 18: IPC Flow Coefficient at Cruise and Take-Off .............................................................................. 36
Figure 19: IPC Pressure Ratio at Cruise and Take-Off ................................................................................. 36
Figure 20: IPC Work Coefficient at Cruise and Take-Off ............................................................................. 37
Figure 21: IPC Degree of Reaction at Cruise and Take-Off ......................................................................... 37
Figure 22: HPC Isometric View .................................................................................................................... 39
Figure 23: HPC Stage 3 Hub Velocity Triangles ........................................................................................... 42
Figure 24: HPC Stage 3 Mid Velocity Triangles ........................................................................................... 43
Figure 25: HPC Stage 3 Tip Velocity Triangles ............................................................................................. 44
Figure 26: HPC h-s Diagram for Stage 3 ...................................................................................................... 45
Figure 27: HPC Meridional View ................................................................................................................. 46
Figure 28: HPC Stage 1 Splitter Blade Detail ............................................................................................... 46
Figure 29:HPC Stagger for Stage 3 Rotor .................................................................................................... 47
Figure 30: HPC Gap to Pitch vs Blade Number ............................................................................................ 47
Figure 31: HPC Number of Blades vs Stage Number .................................................................................. 48
Figure 32: HPC Flow Coefficient at Cruise and Takeoff............................................................................... 51
Figure 33: HPC Pressure Ratio for Cruise and Takeoff ................................................................................ 51
Figure 34: HPC Work Coefficient at Cruise and Takeoff ............................................................................. 52
Figure 35: HPC Degree of Reaction at Cruise and Takeoff .......................................................................... 52
Figure 36: Combustion Chamber ................................................................................................................ 53
Figure 37: Combustion Chamber h-s Diagram ............................................................................................ 54
Figure 38: HPT Isometric View .................................................................................................................... 56
Figure 39: HPT Hub Velocity Triangle.......................................................................................................... 57
Figure 40: HPT Mid Velocity Triangle .......................................................................................................... 58
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Figure 41: HPT Tip Velocity Triangle ........................................................................................................... 59
Figure 42: HPT h-s Diagram ......................................................................................................................... 60
Figure 43: HPT Meridional View ................................................................................................................. 61
Figure 44: Stagger of Rotor Blade ............................................................................................................... 62
Figure 45: Isometric View of IPT ................................................................................................................. 64
Figure 46: HPT-IPT Mid Velocity Triangle .................................................................................................... 65
Figure 47: HPT-IPT Hub Velocity Triangle ................................................................................................... 65
Figure 48: HPT-IPT Tip Velocity Triangle ..................................................................................................... 65
Figure 49: IPT Hub Velocity Triangle ........................................................................................................... 67
Figure 50: IPT Mid Velocity Triangle ........................................................................................................... 68
Figure 51: IPT Tip Velocity Triangle ............................................................................................................. 69
Figure 52: IPT h-s Diagram .......................................................................................................................... 70
Figure 53: IPT Meridional View ................................................................................................................... 71
Figure 54: IPT Stagger ................................................................................................................................. 72
Figure 55: Counter-rotating power turbine [AIAA-85-1190 The Unducted fan engine] ............................ 74
Figure 56: A 3D view of the power turbine (IGV/OGV-red; Rotors-blue; Unearthed Stators-black) .......... 74
Figure 57: Conventional Stage .................................................................................................................... 75
Figure 58: Counter-Rotating Stage.............................................................................................................. 75
Figure 59: Work Split across the Power Turbine ........................................................................................ 76
Figure 60: Work Coefficient of Rotors and Stators across the Power Turbine ........................................... 77
Figure 61: Velocity Triangle at Hub, Mid, and Tip; Rotor 1 Rotating Counter-Clockwise, Stator 1 Rotating
Clockwise .................................................................................................................................................... 80
Figure 62: Stack for the Power Turbine Rotor. ........................................................................................... 81
Figure 63: Stack for the Power Turbine Stator ........................................................................................... 81
Figure 64: Velocity Distribution across the Power Turbine ........................................................................ 82
Figure 65: Flow Coefficient across the Power Turbine ............................................................................... 82
Figure 66: Degree of Reaction for the Power Turbine Components .......................................................... 83
Figure 67: Meridional View of for Station 1, 2, 3 and 4 .............................................................................. 84
Figure 68: h-s Diagram UDF rotor in Relative FoR ...................................................................................... 84
Figure 69: h-s Diagram UDF rotor in Absolute FoR ..................................................................................... 85
Figure 70: Pressure Variation across Power Turbine .................................................................................. 86
Figure 71: Temperature Variation across the Power Turbine .................................................................... 86
Figure 72: The Meridional Flow Path of the Power Turbine ....................................................................... 88
Figure 73: The Number of Blades across the Power turbine ...................................................................... 89
Figure 74: Propfan Isometric View .............................................................................................................. 90
Figure 75: Propfan Airfoil ............................................................................................................................ 91
Figure 76: Propfan 1 snd 2 .......................................................................................................................... 93
Figure 77: Pitch Angles across Flight Conditions......................................................................................... 94
Figure 78: Angle of Attack Across Flight Conditions ................................................................................... 95
Figure 79: Advance Angle Across Flight Conditions .................................................................................... 96
Figure 80: Propfan Cruise Velocity Triangle ................................................................................................ 97
Figure 81: Propfan h-s Diagram .................................................................................................................. 99
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Figure 82: Propfan Aero/Thermo Stations .................................................................................................. 99
Figure 83: Propfan Relative h-s Diagram .................................................................................................. 101
Figure 84: Propfan Aero/Thermo Stations for Relative Frame of Reference ........................................... 101
Figure 85: Detailed Meridional Inlet View with Capture Cones ............................................................... 105
Figure 86: h-s Diagram of Flow through Inlet Diffuser ............................................................................. 106
Figure 87: HPC Exit Diffuser Thermodynamics and h-s Diagram .............................................................. 108
Figure 88: HPC exit Diffuser Meridonial View ........................................................................................... 109
Figure 89: IPT/PT Thermodynamics and h-s Diagram ............................................................................... 109
Figure 90: Detailed Meridional View of IPT/PT Duct ................................................................................ 110
9
List of Tables
Table 1: Requirements for Cycle Analysis ................................................................................................... 14
Table 2: GE 36 UDF Data ............................................................................................................................. 15
Table 3: CFM 56-7B24 ................................................................................................................................. 15
Table 4: Stage Locations ............................................................................................................................. 17
Table 5: Pressure Ratio Values .................................................................................................................... 17
Table 6: Total and Static Pressure for Cruise Conditions Values ................................................................ 18
Table 7: Total and Static Temperature for Cruise Conditions Values ......................................................... 19
Table 8: Total and Static Pressure for Takeoff Conditions Values .............................................................. 20
Table 9: Total and Static Temperature for Takeoff Conditions Values ....................................................... 21
Table 10: Key Engine Thrust and TSFC ........................................................................................................ 22
Table 11: Bleed Effects ................................................................................................................................ 22
Table 12: IPC Design Choices ...................................................................................................................... 24
Table 13: IPC Design Values for each Stage ................................................................................................ 24
Table 14: IPC Design Values at Each Rotor and Stator ................................................................................ 24
Table 15: IPC Alpha and Beta Design Values ............................................................................................... 25
Table 16: IPC Tip Velocity Triangle Data ..................................................................................................... 26
Table 17: IPC Velocity Triangle Data at the Mid ......................................................................................... 27
Table 18: IPC Velocity Triangle Data at the Hub ......................................................................................... 28
Table 19: IPC h-s Diagram Values for the Second Stage ............................................................................. 29
Table 20: IPC Design Values at Off Design .................................................................................................. 33
Table 21: IPC Design Values at each Rotor and Stator at Off Design .......................................................... 34
Table 22: IPC Variable Stator Vane Deflection in Degrees .......................................................................... 34
Table 23: IPC Beta Error Entering the Rotors .............................................................................................. 35
Table 24: HPC Design Choices ..................................................................................................................... 39
Table 25: HPC Design Values at Each Stage ................................................................................................ 40
Table 26: HPC Design Values at Each Rotor and Stator .............................................................................. 40
Table 27: HPC Design Values at each Aero/Thermo Station ....................................................................... 41
Table 28: HPC Stage 3 Hub Velocity Values ................................................................................................ 42
Table 29: HPC Stage 3 Mid Velocity Values ................................................................................................ 43
Table 30: HPC Stage 3 Tip Velocity Values .................................................................................................. 44
Table 31: HPC h-s Diagram Values for Stage 3 ............................................................................................ 45
Table 32:HPC Stagger for Stage 3 Rotor ..................................................................................................... 47
Table 33: HPC Off Design Values at Each Stage .......................................................................................... 48
Table 34: HPC Off Design Values at Each Blade .......................................................................................... 49
Table 35: HPC Variable Stator Vane Deflection .......................................................................................... 50
Table 36: HPC Error in Beta ......................................................................................................................... 50
Table 37: Combustion Chamber Inlet and Outlet ....................................................................................... 53
Table 38: Parameters of Jet-A Fuel ............................................................................................................. 54
Table 39: Combustion Chamber Fuel Parameters ...................................................................................... 55
Table 40: Combustion Chamber Specifics ................................................................................................... 55
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Table 41: HPT Hub Velocity Triangle Values ............................................................................................... 57
Table 42: HPT Mid Velocity Triangle Values ............................................................................................... 58
Table 43: HPT Tip Velocity Triangle Values ................................................................................................. 59
Table 44: HPT h-s Diagram Values .............................................................................................................. 60
Table 45: HPT Radii Values .......................................................................................................................... 61
Table 46: HPT Airfoil Geometry Values ....................................................................................................... 62
Table 47: Key Values for the HPT ................................................................................................................ 63
Table 48: HPT-IPT Velocity Triangle Values................................................................................................. 66
Table 49: IPT Hub Velocity Triangle Values ................................................................................................. 67
Table 50: IPT Mid Velocity Triangle Values ................................................................................................. 68
Table 51: IPT Tip Velocity Triangle Values .................................................................................................. 69
Table 52: IPT h-s Diagram Values ................................................................................................................ 70
Table 53: IPT Radii Values ........................................................................................................................... 72
Table 54: IPT Airfoil Values ......................................................................................................................... 72
Table 55: IPT Key Values ............................................................................................................................. 73
Table 56: Counter-rotating Stage vs. Conventional Stage .......................................................................... 75
Table 57: Power Requirement .................................................................................................................... 76
Table 58: PT Aerodynamic characteristics at TIP ........................................................................................ 78
Table 59: PT Aerodynamic characteristics at MID ...................................................................................... 78
Table 60: PT Aerodynamic characteristics at HUB ...................................................................................... 79
Table 61: Thermodynamic Characteristics across Station 1, 2, 3 and 4 ..................................................... 85
Table 62: Geometry per Station across the Power Turbine ....................................................................... 87
Table 63: Geometry per Component across the Power Turbine ................................................................ 88
Table 64: Propfan Airfoil Data ..................................................................................................................... 91
Table 65: Radial Variation for Propfan ........................................................................................................ 92
Table 66: Propfan Key Geometric Values ................................................................................................... 92
Table 67: Propfan Cruise Velocity Triangle Values ..................................................................................... 98
Table 68: Propfan Cruise Thermodynamic Values .................................................................................... 100
Table 69: Propfan Relative Thermodynamic Values ................................................................................. 102
Table 70: Propfan Off Design Thermodynamic Values ............................................................................. 102
Table 71: Key Propfan Stage Thermodynamic Values- Off Design ........................................................... 103
Table 72: Propfan Cruise Performance ..................................................................................................... 103
Table 73: Propfan Takeoff and SLS Performance ...................................................................................... 104
Table 74: Areas at Locations of Interest Necessary for Inlet Design ........................................................ 105
Table 75: Thermodynamics through Inlet Diffuser at Cruise .................................................................... 106
Table 76: Thermodynamics through Inlet Diffuser at Takeoff .................................................................. 107
Table 77: Diffuser Thermodynamics ......................................................................................................... 108
Table 78: IPT/PT Thermodynamics ........................................................................................................... 109
Table 79: Composition of Ti-6Al-4V .......................................................................................................... 111
Table 80: Properties of Ti-6Al-4V compared with standard Alumina ....................................................... 111
Table 81: Composition of INCONEL® Alloy 706 ......................................................................................... 112
Table 82: Properties of INCONEL® Alloy 706 compared with standard Alumina ..................................... 112
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Table 83: Composition of INCOLOY® alloy A-286 ..................................................................................... 113
Table 84: Properties of INCOLOY® alloy A-286 compared with standard Alumina .................................. 113
Table 85: Properties of YSZ ....................................................................................................................... 114
Table 86: Composition of MAR-M-247 ..................................................................................................... 114
Table 87: Properties of MAR-M-247 ......................................................................................................... 115
Table 88: Mechanical and Thermal Properties of Hastelloy alloy X ......................................................... 116
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Nomenclature
GREEK
Symbol Definition
Δ Change α Absolute Flow Angle αP Angle of Attack
β Relative Flow Angle
βP Pitch Angle
σ Stagger Angle
η Efficiency
λ Work Coefficient, Excess Air
Flow Coefficient, Fuel to Air Equivalence Ratio
φ Specific Fuel Coefficient
φP Advance Angle
π Pressure Ratio
τ Temperature Ratio
Specific Heat Ratio
ζ Loss Coefficient
Ω Rotational Speed
ρ Density
LETTERS
Symbol Definition
A Cross-Sectional Area
AF Activity Factor
C Chord Length
Cp Specific heat at const pressure per unit mass
CP Coefficient of power
CQ Coefficient of Torque
CT Coefficient of Thrust
F Fan
h Specific enthalpy
HPC High Pressure Compressor
HPT High Pressure Turbine
IPC Intermediate Pressure Compressor
IPT Intermediate Pressure Turbine
J Advance Ratio
Mass flow rate
P Pressure
R Gas Constant
RPM Revolutions per minute
r Radius
s Specific Entropy
13
T Temperature
TO Takeoff
U Blade Speed
V Absolute Velocity
W Relative Velocity
Z Zweifel Coefficient
AR Aspect Ratio
FoR Frame of Reference
Ma Mach Number
TR Taper Ratio
SUBSCRIPTS
Symbol Definition
0 Total
ax Axial
h Hub-Span
LE Leading Edge
m Mid-Span
M Mechanical
P1 Propfan 1
P2 Propfan 2
rel Relative Frame of Reference
R1 Rotor 1
R2 Rotor 2
s Stator
ss Static to Static
TE Trailing Edge
t Tip-Span
ts Total to Static
tt Total to Total
u Radial Velocity
Rel Relative Frame of Reference
14
1. Introduction and Competitive Analysis
Growing reliance on the Gas Turbine Engine in the aviation industry is accompanied by dwindling energy
resources. Hiking fuel prices and increased environmental concerns require engineers to employ a
multidisciplinary approach, taking the engine’s environmental and economical impact into account.
Consequently, it is important to develop an engine with innovations which meet or surpass these
expectations. The engine with an unducted propfan(UDF) design has the innovations to surpass the
competition.
1.1 Problem Statement and Requirements The focus of this project is to create an engine comparable to that of the CFM International CFM 56-
7B24. The goal is to improve on the design with innovative features and adjustment to the detailed
design of the engine. The following is a table of requirements that must be met during the cycle analysis
of the engine.
Table 1: Requirements for Cycle Analysis
Cycle Analysis Requirements
ui TO 72 m/s ηM HPT and HPC 96%
Mi Cruise 0.85 ηss HCP to LPT Duct 93%
M7 (Combustor Inlet) 0.1 ηtt LPT 91%
M6 (HPC Diffuser) 0.3 ηM LPT and LPC 96%
Cruise Altitude 34000 ft. ηts Core Nozzle 93%
Cruise Trust ≥40% CFM TO Thrust ηtt Fan 1 92%
sa 10 J/kg*k ηtt Fan 2 92%
∆Po (a to 1) -1% γ 1.4
∆Po Inlet (1 to 2) Cruise: -1% γ(4) 1.39
TO: -1.5% γ(3->4) 1.395
∆Po Combustor (7 to 8) -1.50% γ(6) 1.38
π Overall <42 γ(4->6) 1.385
ηtt IPC 4 Stage: 90% γ(7->8) 1.355
3 Stage: 88% γ(8->12) 1.33
ηss ICP to HPC Duct 94% R 287 J/Kg*K
ηtt HPC 7 Stages: 89% R(CC) 259.8 J/Kg*K
6 Stages: 87% QR 43000000 J/kg
ηss HCP to Diffuser Duct 93% TITmax 2100 K
ηtt HPT 90%
Due to the engine’s innovative Unducted Propfan design, some of the requirements set previously do not apply for both the cycle analysis as well as the detailed fan design. There will be no ducted fan at the entrance of the engine. Instead, and unducted fan is installed at the end of the engine’s design. Further design specification of the unducted prop fan will be discussed in Chapter 9.
15
1.2 Detailed Analysis This design will be taking into comparison not only the CFM 56-7B24 but also the design of the GE-36
Unducted Fan. It will take into consideration some basic performance aspects of the CFM while
concentrating mainly on the GE-36 because of the similarities between the engine and the GE-36. The
engine will attempt to compare aspects such as the fan RPM and fan pressure ratio of the GE-36 while
taking into account characteristics such as the TSFC and Thrust of the CFM 56.
Table 2: GE 36 UDF Data
GE-36 UDF
SLS 25,000 Ibf
Cruise Trust 20.36% SLS Thrust
Fan RPM 1395
Fan Blade Numbers 8-8
Total Pressure Ratio 27
Fan Pressure Ratio 1.17
SFC at Cruise 0.52/hr
Fan Stages 2
IPC Stages 3
HPC Stages 7
HPT Stages 1
LPT Stages 1
Power Turbine 6
Fan Blade Tip Speed at Cruise 238 m/s
Fan Blade Tip Speed at TO 259 m/s
Turbine Inlet Temperature 1545 K
Table 3: CFM 56-7B24
CFM 56-7B24
Thrust TO 24200 lbf
Thrust Cruise 5480 lbf
SFC at Cruise 0.627
Bypass ratio 5.3
Mass Flow 354 kg/s
Turbine Inlet Temperature 1780 K
Total Pressure Ratio 32
Number of Spools 2
Fan Stages 1
LPC Stages 3
HPC Stages 9
HPT Stages 1
LPT Stages 4
16
1.3 Technological Innovations
The UDF was a modified turbofan engine with an attached open, counter–rotating fan blades. Its
advantage is that it offers the speed and performance of a turbofan, with the fuel economy of a
turboprop.
This technology has been proven to work and showed very promising results during its R&D and testing
stage in the 1970’s and 1980’s. NASA and GE collaborated to work on the GE36, while Pratt &Whitney-
Allison pursued the PW 578-DX Propfan. Figure 1 depicts the GE-36, a UDF similar to the engine
illustrated in this report.
The engine designed in this report has an aft mounted, pusher style, counter-rotating propfan. Initial
research shows a slight reduction of carbon and nitrogen oxides emissions and the UDF and saves fuel
when comparing the thrust produced. The UDF blades are variable pitch, which provides the reverse
thrust capability. This allows for reverse thruster mechanism on traditional turbofan engines to be
excluded from this engine, reducing overall weight of the engine. Counter-rotating fans allow recovery
of exit swirl and converting this to thrust, thus increasing efficiency. It is important to note that the
engine fan rotors do not deal with gearings thereby reducing weight, increasing reliability, and cutting
down maintenance costs. The HPC and IPC shafts are counter rotating and the rotation within the power
turbine for the UDF operates under a counter-rotating stage (rotor-rotor) design. A rotor-rotor design
has a work stage that is twice the amount of a conventional stage. This translates to lower stages for the
same work required, reducing the overall weight of the engine. All these factors combined produce an
engine which has high thrust to weight ratios, low specific fuel consumption and higher efficiencies.
Figure 1: Unducted Propfan GE36 (NASA)
17
2. Cycle
2.1 General Information
Cycle analysis was conducted for Cruise (34,000 ft and Mach .85) and Takeoff (Sea Level and Mach .212)
conditions.
Table 4: Stage Locations
Table 5: Pressure Ratio Values
Station Component
a Ambient
1 Inlet
2 Diffuser
3 IPC
4 HPC
5 HPC Diffuser
6 Combustion Chamber
7 HPT
8 IPT
9 IPT-PT Duct
10 Power Turbine
11 Core Nozzle
21 Propeller 1
22 Propeller 2
UDF
TO Cruise
π0 Core 25.24 28
π0F1 1.20 1.116
π0F2 1.18 1.114
π0 IPC 3.577 4
π0 HPC 7.056 7
a
21
7
8
9 10
11
1 2 5 6
3 4
22
Hauenstein, Palmer, Khan, Hobbs
18
2.2 Cycle at Design: Cruise
The pressure trend at cruise for the engine is shown in Figure 2 and the calculated values are shown in
Table 6. Pressure is increasing until the combustion chamber Inlet where the pressure begins to
decrease to the exhaust of the engine. The pressure across the fan stays almost constant.
Figure 2: Total and Static Pressure for cruise conditions
Table 6: Total and Static Pressure for Cruise Conditions Values
Ambient Inlet Diffuser IPC HPC
HPC Diffuser
Combustion Chamber
HPT IPT IPT/Power Turbine
Duct
Power Turbine
Core Nozzle
Po (Pa) 40198.1 39796.1 39398.2 156035.0 1072385.7 1084392.1 1068126.2 352686.4 200934.8 198614.6 39723.5 38395.4
P (Pa) 25064.0 28176.7 28403.2 128817.5 912910.2 1076942.6 978346.2 247190.9 166466.2 194874.9 38369.4 25064.0
The temperature trend at cruise for the engine is shown in Figure 3 and the calculated values are shown
in Table 7. Temperature is increasing until the HPT where the temperature begins to decrease to the
exhaust of the engine. The trend mimics that of the pressure across the engine.
0.0
200000.0
400000.0
600000.0
800000.0
1000000.0
1200000.0
Total and Static Pressure (Pa)
Po
P
19
Figure 3: Total and Static Temperature for Cruise Conditions
Table 7: Total and Static Temperature for Cruise Conditions Values
Ambient Inlet Diffuser IPC HPC
HPC Diffuser
Combustion Chamber
HPT IPT IPT/Power
Turbine Duct
Power Turbine
Core Nozzle
To(K) 252.8 252.8 252.8 393.3 719.7 719.7 1558.1 1226.6 1079.6 1079.6 757.5 757.5
T (K) 220.9 229.1 230.3 372.7 688.5 723.0 1524.5 1123.1 1030.3 1074.5 751.0 681.4
Below displays the Mach number trend throughout the engine at cruise.
Figure 4: Mach Number Trend at Cruise
0.00
500.00
1000.00
1500.00
2000.00 Total and Static Temperature (K)
To
T
0
0.2
0.4
0.6
0.8
1
Mach Number
20
2.3 Cycle at off-design: Take-off
The pressure trend at take-off for the engine is shown in Figure 5 and the calculated values are shown in
Table 8. The pressure increases until the combustion chamber inlet where the pressure begins to
decrease to the exhaust of the engine.
Figure 5: Total and Static Pressure for Takeoff Conditions
Table 8: Total and Static Pressure for Takeoff Conditions Values
Ambient Inlet Diffuser IPC HPC HPC
Diffuser Combustion
Chamber HPT IPT
IPT/Power Turbine Duct
Power Turbine
Core Nozzle
Po (Pa) 104522.9 103477.7 101925.6 364636.3 2573014.5 2544118.8 2505957.1 698997.8 400344 394185.2 103740.4 103567.2
P (Pa) 101300.0 82286.1 81474.6 305881.6 2167150.5 2526641.4 2288149.6 614838.2 310991 384375.0 100894.4 101300.0
The temperature trend at take-off for the engine is shown in Figure 6 and the calculated values are
shown in Table 9. The temperature increases until the HPT inlet where the temperature begins to
decrease to the exhaust of the engine. The maximum temperature is higher at take off due to a higher
TIT takeoff.
0.0
500000.0
1000000.0
1500000.0
2000000.0
2500000.0
3000000.0
Total and Static Pressure (Pa)
Po
P
21
Figure 6: Total and Static Temperature for Takeoff Conditions
Table 9: Total and Static Temperature for Takeoff Conditions Values
Below is a figure representing the Mach number trend across the engine at takeoff.
Figure 7: Mach number Trend at Take-Off
0.00
500.00
1000.00
1500.00
2000.00Total and Static Temperature (K)
To
T
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Mach Number
Ambient Inlet Diffuser IPC HPC
HPC Diffuser
Combustion Chamber
HPT IPT IPT/Power
Turbine Duct
Power Turbine
Core Nozzle
To(K) 290.6 290.6 290.6 436.1 795.0 795.0 1672.9 1264.1 1117.2 1117.2 836.8 836.8
T (K) 288.0 272.2 272.6 415.2 758.3 793.5 1635.6 1224.5 1049.3 1110.2 831.1 832.2
22
2.4 Key Engine Performance Values
The key engine performance values from the cruise cycle design are tabulated in Table 10. All thrust
requirements were met with the cruise thrust at exactly 40% of the competitors take-off thrust. Both
the take-off and SLS thrust values match that of the CFM exactly. The thrust was chosen not to be
raised above the minimum constraints due to fuel savings. The conclusion was made that having a fuel
savings at cruise was more important than exceeding the thrust. As a result, the engine was able to
achieve a competitive cruise TSFC of the CFM 56-7B24.
Table 10: Key Engine Thrust and TSFC
Propfan Thrust
(lbs) Core Thrust
(lbs) Net Thrust
(lbs) Propfan Thrust
Percentage Core Thrust Percentage
TSFC (1/h)
Cruise 6362.0 1039.6 7401.6 86.0% 14.0% 0.630
Takeoff 14713.0 3791.0 18504.0 79.5% 20.5% 0.557
SLS 19400 4607.3 24200.0 80% 20% 0.434
2.5 Customer and Cooling Bleeds
A customer bleed of 5% was taken out of the HPC at station 10. A cooling bleed of 0.3% was taken out of
the HPC at station 15 behind the last stator. These stations were chosen to meet the criteria of having a
static pressure of 450 kPa for the customer bleed and using a station with 20 psi higher pressure than
the trailing edge of the cooled part. There is a slight loss in fuel savings when the bleeds are added as
well as uniform increase in work over all the components. These results were to be expected due to a
loss in mass flow.
Table 11: Bleed Effects
With Bleeds With Out Bleeds % Diff
ΔhO HPT (J/kg) 347064.7 329668.7 5.28
ΔhO LPT (J/kg) 153949.2 146232.7 5.28
ΔhO PT (J/kg) 337287.1 320381.2 5.28
TIT (K) 1558.1 1482.3 5.12
TSFC at Cruise (1/hr) 0.630 0.621 1.51
23
3. Intermediate Pressure Compressor (IPC)
The engine is equipped with a four stage intermediate pressure compressor as shown below in Figure 8.
It is equipped with a variable inlet guide vane and variable stator vanes.
3.1 IPC at Design Condition: Cruise
The key IPC design choices, design criteria, and the results from thermodynamics, aerodynamics, and
geometric analysis for the IPC at cruise are described in the subsections below.
Figure 8: IPC Isometric View
Hobbs, Burch
24
3.1.1 Key IPC design choices and criteria
The key design choices selected for the IPC and the design criteria that needed to be met are described
in this subsection. Table 12 below shows the design specifications selected to create the rotor and stator
blades.
Table 12: IPC Design Choices
RPM 13,800
AR – Rotors 2.2
AR – Stators 4
H/T 0.68
TR – Rotors 0.8
TR - Stators 1.2
Table 13, Table 14 and Table 15 show that none of the design criteria has been violated and that all of
the IPC detail design is within the limits stated. Please note that in Table 14 the columns highlighted are
the important values of interest. The Δ α requirement is only for the stator blades while the Δ β
requirement is for the rotor blades.
Table 13: IPC Design Values for each Stage
Stage 1 Stage 2 Stage 3 Stage 4 Criteria
Lambda ‘λ’ 0.207 0.195 0.171 0.181 <0.55
Phi ‘Φ’ 0.388 0.401 0.463 0.482 ----
R 0.901 0.868 0.779 0.705 ----
Table 14: IPC Design Values at Each Rotor and Stator
IGV Rotor 1 Stator 1 Rotor 2 Stator 2 Rotor 3 Stator 3 Rotor 4 Stator 4 Criteria
Diffusion Factor
DF tip 0.000 0.279 0.341 0.259 0.358 0.217 0.237 0.207 0.199 ----
DF mid 0.009 0.360 0.400 0.312 0.415 0.250 0.277 0.237 0.232 ----
DF hub 0.021 0.426 0.476 0.392 0.488 0.300 0.330 0.279 0.276 ----
DF Avg 0.010 0.355 0.406 0.321 0.420 0.256 0.282 0.241 0.236 <0.45
Delta Alpha (deg)
Tip 6.7 40.6 28.5 26.9 30.5 21.6 22.9 19.5 19.5 < 45
Mid 8.0 27.4 25.4 24.2 27.2 19.1 20.1 17.1 17.1 < 45
Hub 9.9 24.6 22.8 21.8 24.4 17.1 17.9 15.2 15.2 < 45
Delta Beta (deg)
Tip 4.9 6.8 9.3 9.3 9.7 10.4 6.7 12.3 7.2 < 45
Mid 2.3 4.2 4.7 5.5 5.4 7.4 4.0 9.2 4.5 < 45
Hub 2.4 1.7 2.7 3.6 3.3 5.7 2.6 7.2 3.0 < 45
25
Table 15: IPC Alpha and Beta Design Values
IGV Station 1
Station 2
Station 3
Station 4
Station 5
Station 6
Station 7
Station 8
Station 9
Criteria
Alpha (deg)
Tip 0 6.7 31.3 8.5 30.4 6.0 23.1 5.2 20.4 5.2 < 71
Mid 0 8 35.4 10 34.2 7 26.1 6 23.1 6 < 71
Hub 0 9.9 40.6 12.1 39.0 8.4 30.1 7.2 26.6 7.1 < 71
Beta (deg)
Tip 70.5 69.1 67.5 70.2 66.5 69.9 64.1 66.7 59.5 59.5 < 71
Mid 68.3 66.0 61.8 66.6 61.1 66.5 59.1 63.1 53.9 53.9 < 71
Hub 63.8 58.9 52.1 61.4 52.1 61.8 51.4 58.2 45.9 45.9 < 71
Important conclusions and observations:
The IPC meets all the design requirements. The work coefficients ‘λ’ per stage are less than 0.55 as
specified in the requirements. Lambda reaches a high value of 0.27 in stage one of the IPC, which means
the IPC is lightly loaded compared to the maximum limit since the HPC is responsible for most of the
compression work.
The average diffusion factor across the hub, mid, and tip of each blade is less than 0.45 which provides
the adequate surge margin required. All alpha and beta angles are less than 71 degrees. In addition,
delta alpha across the stator blades and delta beta across the rotor blades is less than 45 degrees as
specified.
3.1.2 Aerodynamic Analysis
The following figures and tables depict the values for the IPC stage 2 velocity triangles at the hub, mid
and tip. The beta angles are located between W and Vax while the alpha angles are located between V
and Vax.
26
Figure 9: IPC Velocity Triangles at the Tip of the Second Stage
Table 16: IPC Tip Velocity Triangle Data
TIP Rotor 2 Entrance Stator 2 Entrance Stator 2 Exit
U (m/s) 553.8 520.5 500.4
Vax (m/s) 189.6 180.2 176.6
V (m/s) 191.8 208.8 177.5
W (m/s) 558.5 452.3 513.2
Wu (m/s) 525.3 414.9 481.9
Vu (m/s) 28.4 105.6 18.5
Beta 70.2 66.5 69.9
Alpha 8.5 30.4 6.0
27
Figure 10: IPC Velocity Triangle at the Mid of the Second Stage
Table 17: IPC Velocity Triangle Data at the Mid
MID Rotor 2 Entrance Stator 2 Entrance Stator 2 Exit
U (m/s) 471.0 448.9 427.8
Vax (m/s) 189.6 180.2 176.6
V (m/s) 192.6 217.8 177.9
W (m/s) 476.9 372.9 442.8
Wu (m/s) 437.6 326.4 406.1
Vu (m/s) 33.4 122.4 21.7
Beta 66.6 61.1 66.5
Alpha 10 34.2 7
28
Figure 11: IPC Velocity Triangle at the Hub of Second Stage
Table 18: IPC Velocity Triangle Data at the Hub
Rotor 2 Entrance Stator 2 Entrance Stator 2 Exit
U (m/s) 388.3 377.3 355.1
VAX (m/s) 189.6 180.2 176.6
V (m/s) 193.9 231.7 178.5
W (m/s) 396.1 293.4 373.4
WU (m/s) 347.7 231.6 329.0
VU (m/s) 40.6 145.7 26.1
Beta 61.4 52.1 61.8
Alpha 12.1 39.0 8.4
Important conclusions and observations:
The IPC aerodynamic geomerty is following its natural trend. Across the rotor in the relative frame of
reference W and beta are decrease while V and alpha are increasing in the absolute frame of reference.
The rotor blades are rotating clockwise and counter rotating in conjunction with the HPC.
29
3.1.3 Thermodynamic analysis
Below is the h-s diagram for the second stage of the IPC and the corresponding stage characteristic
values in the absolute FoR.
Figure 12: IPC h-s Diagram of the Second Stage in the absolute FoR
Below is the h-s table for the second stage of the IPC and the corresponding stage characteristic values.
Table 19: IPC h-s Diagram Values for the Second Stage
Rotor 2 Entrance Stator 2 Entrance Stator 2 Exit M 0.6 0.6 0.5
Po (Pa) 68655.4 100951.6 100236.9 P (Pa) 55101.6 78564.7 84968.4 To (K) 303.1 341.7 341.5 T (K) 284.7 318.1 325.8
ho (J/Kg) 304861.3 344075.6 344075.6 h (J/kg) 286319.0 320349.0 328253.5
CP (J/kg*K) 1005.8 1007.1 1007.5 γ 1.3993 1.3986 1.3983
ρ (kg/m3) 0.235 0.193 0.187
30
Important conclusions and observations:
As shown above, the thermodynamics for the IPC follows the normal compression trend. Pressure is
increasing across the stage. Variable Cp is increasing across the IPC
3.1.4 Geometric Analysis
The meridional view of the IPC is show below. The stator blades shown in Figure 13 are turned slightly
to show the angle they are positioned at in reference to the rotor blades.
Figure 13: IPC Meridional View
31
Figure 14: IPC Stagger
Rotor 2 Stagger
TIP 68.3
MID 63.8
HUB 56.8
32
Figure 15 below is the gap to pitch ratio across the IPC.
Figure 15: IPC Gap to Pitch Ratio
Figure 16: IPC Number of Blades vs Stages
0.0000
0.0500
0.1000
0.1500
0.2000
0.2500
0.3000
0.3500
0.4000
0.4500
0 1 2 3 4 5 6 7 8 9
Gap
/S
Blade Number
Gap/S vs Stage
0
10
20
30
40
50
60
70
80
90
1 2 3 4 5
NO
B
Stages
Number of Blades per IPC Stage
Stators
Rotors
33
Important conclusions and observations:
The reason for the unusual trend of blade numbers across the IPC is due to the variation in aspect ratio
across the rotors and stators. The aspect ratio across the rotors is 2.2 while the aspect ratio across the
stators is 4. Increasing the aspect ratio in the stators will increase the number of stator blades in each
stage. Although the best way to attain a smooth annulus is by altering the Vax and rmid these values could
no longer be altered at a certain point without affecting other key parameters. Instead it was chosen to
then alter the aspect ratio to keep the annulus as smooth as possible. The area of the IPC changes from
.328 at the entrance of the IGV to 0.122 at the exit of the last stator
3.2 Off Design Condition: Takeoff
The IPC, design criteria, and trend charts and design and off design for the IPC at cruise are described in
the subsections below.
3.2.1 IPC design criteria
The design criteria that the IPC needed to meet at off design are described in this subsection. Table 20 and Table 21 shows that none of the design criteria has been violated and that all of the IPC detail design at take-off is within the limits stated. Please note that in Table 21 the columns highlighted are the important values of interest. The Δ α requirement is only for the stator blades while the Δ β requirement is for the rotor blades.
Table 20: IPC Design Values at Off Design
Stage 1 Stage 2 Stage 3 Stage 4 Criteria
Lambda ‘λ’ 0.311 0.192 0.157 0.151 <0.55
Phi ‘Φ’ 0.325 0.353 0.355 0.393 ----
R 0.891 0.761 0.742 0.690 ----
34
Table 21: IPC Design Values at each Rotor and Stator at Off Design
IGV Rotor 1 Stator 1 Rotor 2 Stator 2 Rotor 3 Stator 3 Rotor 4 Stator 4 Criteria
Diffusion Factor
DF tip -0.029 0.425 0.466 0.280 0.363 0.221 0.226 0.191 0.149 ----
DF mid -0.021 0.514 0.536 0.344 0.428 0.256 0.274 0.216 0.187 ----
DF hub -0.011 0.178 0.603 -0.049 0.552 -0.031 0.337 -0.019 0.238 ----
DF Avg -0.020 0.372 0.535 0.192 0.448 0.149 0.279 0.129 0.191 <0.45
Delta Alpha
Tip 6.7 37.3 26.1 21.1 27.2 15.8 20.1 12.7 17.0 < 45
Mid 8 40.0 27.4 22.2 29.2 17.1 22.1 14.1 19.1 < 45
Hub 9.8 42.8 28.3 22.9 31.1 18.5 24.5 15.8 21.7 < 45
Delta Beta
Tip 2.7 1.2 2.7 4.0 2.5 5.3 1.4 6.3 1.5 < 45
Mid 3.7 4.0 5.6 6.4 5.0 7.1 2.9 8.0 3.0 < 45
Hub 4.0 13.3 13.5 11.8 11.0 10.3 6.1 10.8 5.9 < 45
Important conclusions and observations:
The IPC meets all the design requirements at off design. The work coefficients ‘λ’ per stage are less than
0.55 as specified in the requirements. Lambda reaches a high of 0.311 in stage one of the IPC which
means the IPC is moderately loaded compared to the maximum limit since the HPC is doing most of the
compressive work. The average diffusion factor across the hub, mid, and tip of each blade is less than
0.45 which provides the adequate surge margin required.
3.2.2 Geometry Analysis
At off design the stator geometry of the IPC changes slightly. The RPM decreases from 13,800 at cruise
to 13,330 at take-off approximately a 3.4% decrease. The IPC has three variable stator vanes as well as a
variable IGV. Table 22 below shows the angle change on the variable stators and IGV. Table 23 shows
the Beta error values entering the rotor blades of the IPC.
Table 22: IPC Variable Stator Vane Deflection in Degrees
IGV Stator 1 Stator 2 Stator 3 Stator 4 VSV Deflection 2.4 13 9 5 0
35
Table 23: IPC Beta Error Entering the Rotors
Rotor 1 Rotor 2 Rotor 3 Rotor 4 Criteria
TIP 0.78 1.23 0.03 -0.74 2<β<2
MID -0.2 0.92 -0.4 -1.1 2<β<2
HUB 2.0 -0.13 -1.3 -1.8 2<β<2
Important conclusions and observations:
Although the design criteria for change of RPM between take-off and cruise is 3% and the engine is at
3.4 % it is not uncommon for engines to have a higher percent increase/decrease between takeoff and
cruise conditions. After reviewing several FAA Type Certificate Data Sheets, it was observed that there
are similar engines in service that operate with a higher percent increase/decrease. Shown below in
Figure 17, the GE90-76B has a nine percent decrease between take-off and cruise conditions. The three
variable stator vanes were used to decrease the difference in beta angles between cruise and take-off
on the leading edge of the rotors. All errors in beta are within the allowed clearance of two degrees.
Figure 17: GE90-76B RPM at Take-Off and Cruise Conditions
36
3.2.3 Key IPC trends
Some key trends of the IPC at cruise and take-off are shown below.
Figure 18: IPC Flow Coefficient at Cruise and Take-Off
Figure 19: IPC Pressure Ratio at Cruise and Take-Off
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0 1 2 3 4 5
# of stage
Flow Coefficient 'φ'
Cruise
T.O.
00.20.40.60.8
11.21.41.61.8
2
0 1 2 3 4 5
# of stage
Pressure Ratio 'π'
Cruise
T.O.
37
Figure 20: IPC Work Coefficient at Cruise and Take-Off
Figure 21: IPC Degree of Reaction at Cruise and Take-Off
0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
0 1 2 3 4 5
# of stage
Work Coefficient 'λ'
Cruise
T.O.
0.000
0.200
0.400
0.600
0.800
1.000
0 1 2 3 4 5
# of stage
Degree of Reaction 'R'
Cruise
T.O.
38
Important conclusions and observations:
The trends between design and off design are fairly similar. The Flow coefficient graph follows the
proper trend which should look like a relatively flat straight line. The flow coefficient graph increases by
less than a tenth of a point. The pressure ratio between take-off and cruise has a downward trend as
does the work coefficient. Although, the work coefficient at cruise has more of a shallow trend than that
at take-off.
39
4. High Pressure Compressor (HPC)
The engine is equipped with a seven stage HPC as shown below in Figure 22.
Figure 22: HPC Isometric View
4.1 HPC at Design Conditions: Cruise
4.1.1 Aerodynamic Analysis
Table 24 below shows the design selection used to create the rotor and stator blades.
Table 24: HPC Design Choices
RPM 14,775
AR – Rotors 2
AR – Stators 2
H/T 0.7
TR – Rotors 0.8
TR - Stators 1.25
Burch, Hobbs, Dantis
40
Table 25, Table 26, and Table 27 show the design criteria and design values for the HPC detail design.
Please note that in Table 26 the columns highlighted are the important values of interest. The Δ α
requirement is only for the stators while the Δ β requirement is for the rotors.
Table 25: HPC Design Values at Each Stage
Stage 1 Stage 2 Stage 3 Stage 4 Stage 5 Stage 6 Stage 7 Criteria
Lambda ‘λ’ 0.586 0.420 0.373 0.365 0.364 0.363 0.387 λ<.55
Phi ‘Φ’ 0.508 0.559 0.628 0.628 0.653 0.679 0.692 .25<φ<.75
R 0.818 0.664 0.546 0.572 0.562 0.586 0.686 .1<R<1
Table 26: HPC Design Values at Each Rotor and Stator
ROTOR 1 STATOR 1 ROTOR 2 STATOR 2 ROTOR 3 STATOR 3 ROTOR 4 STATOR 4
DIFFUSION FACTOR
DF AVG 0.55 0.52 0.50 0.38 0.43 0.45 0.43 0.47
DELTA ALPHA
TIP 47.30 31.94 30.46 22.29 22.62 22.34 22.62 24.32
MID 52.06 34.56 32.06 23.56 23.25 23.25 23.18 25.18
HUB 57.77 37.42 33.65 24.88 23.80 24.18 23.70 26.07
DELTA BETA
TIP 11.88 8.42 13.74 8.07 15.85 14.26 15.24 15.16
MID 18.97 15.33 18.38 12.64 19.52 18.50 18.39 18.90
HUB 32.50 28.49 25.47 19.82 24.35 24.19 22.37 23.68
ROTOR 5 STATOR 5 ROTOR 6 STATOR 6 ROTOR 7 STATOR 7 CRITERIA
DIFFUSION FACTOR
DF AVG 0.41 0.45 0.12 0.45 0.17 0.45 < 0.45
DELTA ALPHA
TIP 22.36 25.09 22.77 28.42 25.91 31.65 < 45
MID 22.92 25.92 23.32 29.32 26.59 32.59 < 45
HUB 23.45 26.77 23.87 30.26 27.29 33.58 < 45
DELTA BETA
TIP 15.94 15.38 15.73 15.66 14.75 15.96 < 45
MID 18.45 18.36 17.64 18.10 16.35 17.94 < 45
HUB 21.47 21.99 19.87 20.97 18.19 20.21 < 45
41
Table 27: HPC Design Values at each Aero/Thermo Station
STATION 1 2 3 4 5 6 7 8
ALPHA
TIP -5.11 42.20 10.26 40.72 18.43 41.05 18.67 41.30
MID -6.00 46.06 11.50 43.56 20.00 43.25 20.00 43.22
HUB -7.27 50.49 13.07 46.73 21.85 45.65 21.43 45.15
BETA
TIP -65.31 -53.43 -61.86 -48.11 -56.18 -40.33 -54.61 -39.39
MID -61.97 -43.00 -58.33 -39.95 -52.59 -33.07 -51.49 -32.98
HUB -57.80 -25.30 -53.79 -28.32 -48.14 -23.79 -48.00 -25.65
STATION 9 10 11 12 13 14 15 CRITERIA
ALPHA
TIP 16.98 39.49 14.32 37.16 8.65 34.63 2.90 <71
MID 18.00 40.94 15.00 38.36 9.00 35.63 3.00 <71
HUB 19.07 42.54 15.76 39.64 9.38 36.68 3.11 <71
BETA
TIP -54.53 -38.16 -53.78 -37.89 -53.75 -38.86 -54.99 <71
MID -52.01 -33.49 -51.93 -34.20 -52.39 -35.95 -53.98 <71
HUB -49.31 -27.85 -49.82 -29.96 -50.91 -32.72 -52.92 <71
42
Figure 23 below shows the hub velocity triangle followed by Table 28 with the numerical values
Figure 23: HPC Stage 3 Hub Velocity Triangles
Table 28: HPC Stage 3 Hub Velocity Values
Rotor 3 Entrance Stator 3 Entrance
Stator 3 Exit
U (m/s) 329.11 333.46 335.54 VAX (m/s) 216.94 227.79 223.24 V (m/s) 233.74 325.88 239.81 W (m/s) 325.09 248.95 333.63 WU (m/s) 242.11 100.42 247.94 VU (m/s) 87.00 233.04 87.60
β 48.14 23.79 48.00 α 21.85 45.65 21.43
43
Figure 24 below shows the mid velocity triangle followed by Table 29 with the numerical values
Figure 24: HPC Stage 3 Mid Velocity Triangles
Table 29: HPC Stage 3 Mid Velocity Values
Rotor 3 Entrance
Stator 3 Entrance
Stator 3 Exit
U (m/s) 329.11 333.46 335.54 Vax (m/s) 216.94 227.79 223.24
V (m/s) 233.74 325.88 239.81 W (m/s) 325.09 248.95 333.63
Wu (m/s) 242.11 100.42 247.94 Vu (m/s) 87.00 233.04 87.60
Beta 48.14 23.79 48.00 Alpha 21.85 45.65 21.43
44
Figure 25 below shows the tip velocity triangle followed by
Table 30 with the numerical values.
Figure 25: HPC Stage 3 Tip Velocity Triangles
Table 30: HPC Stage 3 Tip Velocity Values
Rotor 3
Entrance Stator 3 Entrance Stator 3 Exit
U (m/s) 396.10 391.76 389.68 VAX (m/s) 216.94 227.79 223.24 V (m/s) 228.67 302.05 235.64 W (m/s) 389.77 298.82 385.46 WU (m/s) 323.82 193.40 314.24 VU (m/s) 72.28 198.36 75.43
β 56.18 40.33 54.61 α 18.43 41.05 18.67
Important conclusions and observations
The work coefficient for stage 1 is the highest in the HPC and is held to a greater limit than the other
stages due to its added splitter blades. The Diffusion Factor for highly loaded compressors can range
from .52 to .58 according to Dickens and Day from reference [3].
45
4.1.2 Thermodynamic Analysis
Below is the h-s diagram for the third stage of the HPC and the corresponding stage values.
Figure 26: HPC h-s Diagram for Stage 3
Table 31: HPC h-s Diagram Values for Stage 3
STAGE 3 1 2 3
M 0.557 0.739 0.536
γ 1.385 1.382 1.379
R [J/kg*K] 287 287 287
CP [J/kg*K] 1033.1 1039.0 1044.0
PO [kPa] 750989.6 1011297.4 1002414.3
P [kPa] 609690.1 706467.9 826527.1
TO [K] 548.4 601.9 599.0
T [K] 517.6 545.1 568.1
V [m/s] 252.5 343.5 254.2
hO [J/kg] 566585.7 625403.2 625403.2
ρ [kg/m3] 4.105 4.515 5.069
46
Important conclusions and observation
The thermodynamic table shows increasing static pressure across the stage but a decrease in total
pressure across the stator, which should be expected. Similarly there is a total temperature drop across
the stator even though total enthalpy does not change due to the variable Cp.
4.1.3 Geometric Analysis
Figure 27: HPC Meridional View
Figure 28: HPC Stage 1 Splitter Blade Detail
0.15
0.17
0.19
0.21
0.23
0.25
0.27
0.29
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 0.22 0.24 0.26 0.28
47
Figure 29:HPC Stagger for Stage 3 Rotor
Table 32:HPC Stagger for Stage 3 Rotor
Stagger
TIP 48.3
MID 42.8
HUB 36.0
Figure 30: HPC Gap to Pitch vs Blade Number
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 2 4 6 8 10 12 14 16
# of Stage
Gap to Pitch
48
Figure 31: HPC Number of Blades vs Stage Number
Important conclusions and observations
The gap to pitch at station 10 does not follow the same trend as the other stations, because the gap at
that station is doubled to allow for the customer bleed to be extracted. There is no second doubled gap
to pitch for the HPT stator bleed because that bleed is taken just aft of Stator 7 so no blade gap is
needed. The number of blades of Rotor 1 is high because the solidity of the rotor was doubled to
account for the splitter blades that were added to that rotor. These splitter blades were added to
extract more work from the flow while still mitigating flow separation issues.
4.2 HPC at Off Design Conditions: Takeoff
4.2.1 HPC Design Criteria
Table 33: HPC Off Design Values at Each Stage
Stage 1 Stage2 Stage3 Stage4 Stage5 Stage6 Stage7 Criteria
Lambda ‘λ’ 0.466 0.413 0.417 0.354 0.390 0.422 0.440 λ<.55
Phi ‘φ’ 0.637 0.700 0.736 0.782 0.764 0.741 0.719 .25<φ<.75
R 0.741 0.647 0.553 0.425 0.517 0.661 0.766 .1<R<1
0
20
40
60
80
100
120
140
160
180
200
1 2 3 4 5 6 7
Number of Blades
Rotors
Stators
49
Table 34: HPC Off Design Values at Each Blade
ROTOR 1 STATOR 1 ROTOR 2 STATOR 2 ROTOR 3 STATOR 3 ROTOR 4 STATOR 4
DIFFUSION FACTOR
DF AVG
0.48 0.47 0.40 0.38 0.40 0.47 0.30 0.48
DELTA ALPHA
TIP 0.23 0.26 0.26 0.48 0.48 0.78 0.78 0.96
MID 177.63 154.80 157.49 117.91 158.68 144.54 134.39 147.34
HUB 26.67 63.41 60.24 47.01 48.26 49.39 47.00 46.78
DELTA BETA
TIP 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
MID 38.56 32.56 30.56 21.56 26.25 23.25 20.22 23.22
HUB 83.62 71.05 88.05 65.85 100.11 98.71 103.18 102.30
ROTOR 5 STATOR 5 ROTOR 6 STATOR 6 ROTOR 7 STATOR 7 CRITERIA
DIFFUSION FACTOR
0.35 0.45 0.41 0.43 0.45 0.41 < 0.45
DELTA ALPHA
0.96 0.26 0.26 0.07 0.07 0.00 < 45
148.02 159.71 160.51 174.23 167.24 167.29 < 45
46.75 50.44 48.50 52.35 50.44 50.03 < 45
DELTA BETA
5.04 0.00 0.00 0.00 0.00 0.00 < 45
23.94 26.94 27.86 30.86 30.63 30.63 < 45
96.00 80.53 72.60 64.49 52.88 53.78 < 45
4.2.2 Geometric Analysis
At off design the high pressure shaft moves from 14775rpm to 15520rpm, which is an increase of 5%.
Justification for this rpm increase was covered in the IPC design. Table 35 below shows the deflection of
the Variable Stator Vanes (VSVs) where a positive angular deflection is in the clockwise direction. The
error in beta entering the rotor is presented in Table 36 seen below.
50
Table 35: HPC Variable Stator Vane Deflection
VSV
Deflection
Stator 1 Stator 2 Stator 3 Stator 4 Stator 5 Stator 6 Stator 7
11.5 10 8 9 9 6 0
Table 36: HPC Error in Beta
Beta Error Rotor 1 Rotor 2 Rotor 3 Rotor 4 Rotor 5 Rotor 6 Rotor 7 Criteria
TIP 0.23 0.26 0.26 -0.34 -0.34 -0.78 -0.78 -2<β<2
MID 0.24 -0.39 -0.39 -0.99 -0.99 -1.28 -1.28 -2<β<2
HUB 0.26 -1.46 -1.46 -1.96 -1.96 -1.92 -1.92 -2<β<2
Important conclusions and observations
Six VSVs were utilized at off design to normalize the beta values on the leading edge of the
rotors to cruise values. Rotational speed varied by 5%, which is higher than recommended but
is within range for the CFM-56-7B. All errors in beta are within the mandated 2 degrees.
51
4.2.3 Key HPC Trends
Some key trends of the HPC at cruise and take-off are shown below.
Figure 32: HPC Flow Coefficient at Cruise and Takeoff
Figure 33: HPC Pressure Ratio for Cruise and Takeoff
0
0.2
0.4
0.6
0.8
1
0 1 2 3 4 5 6 7 8
# of Stage
Flow Coeffecient
CRUISE
TAKEOFF
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0 1 2 3 4 5 6 7 8
# of Stage
Pressure Ratio
CRUISE
TAKEOFF
52
Figure 34: HPC Work Coefficient at Cruise and Takeoff
Figure 35: HPC Degree of Reaction at Cruise and Takeoff
Important conclusions and observations
The trends for off design are more jagged when compared to the design points trends, which is to be
expected, but the values still fall into acceptable ranges.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 2 4 6 8
# of Stage
Work Coeffecient
CRUISE
TAKEOFF
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 2 4 6 8
# of Stage
Degree of Reaction
CRUISE
TAKEOFF
53
5. Combustion Chamber
The combustion chamber is an annular combustor that is made from INCOLOY® alloy A-286. The combustion chamber is explained in detail in the tables below.
The given inlet conditions and the required outlet conditions are as referenced in the tables below. The combustion chamber had to perform as per the given criteria.
Table 37: Combustion Chamber Inlet and Outlet
Inlet Conditions Outlet Conditions
P0 1084392.12 Pa P0 1068126.24 Pa
T0 719.72 K T0 1558.08 K
M 0.1 M 0.36
Figure 36: Combustion Chamber
Dantis, Palmer
54
The figure above refers to the h-s diagram of the process that takes place in the combustion chamber. As can be seen from the figure, the upwards arrow indicates the compression done in the HPC. This compression takes us to pressure gradient P07. However, the total pressure migrates onto the P08 line. This is due to the addition of Jet-A fuel which is ignited with the compressed air, raising the temperature but causing a drop in the total pressure. As per the design constraint, the drop in the pressure is 1.5% to total pressure entering the combustion chamber. The arrow from P08 to P09 signifies the further drop in pressure as we proceed through the HPT.
An important parameter to be taken into account during the calculations for the combustion chamber is the type of fuel used. Today, the most common fuel used today is the Jet-A fuel. Table 38 highlights the pertinent properties of the fuel.
Table 38: Parameters of Jet-A Fuel
Criteria Jet A Fuel
Flashpoint (K) 311
Auto-Ignition Temperature (K) 483
Open Air Burning Temperature (K) 560
Specific Energy (MJ/kg) 42.8
Figure 37: Combustion Chamber h-s Diagram
55
The combustion chamber is designed completely at cruise. Based on the current mass flow and the cycle analysis, the following parameters were calculated.
Table 39: Combustion Chamber Fuel Parameters
Criteria Value
(kg/s) 28.41
(kg/s) 5.89
(kg/s) 15.97
f 0.0207
fprimary zone 0.0368
fst 0.131
Φ (fuel/air equivalence ratio) 0.9512
λ (% excess air) 256.4
From the above calculations, it is determined that there is a fuel lean mixture in the combustion chamber. This ensures that all the fuel is burnt. Hence the combustion chamber is parametrically efficient. From the amount of air mass flow through the combustion chamber, the appropriation of air through the primary zones, secondary zones and dilution holes need to be determined. The values after calculation are given as follows.
Table 40: Combustion Chamber Specifics
Criteria Value
(kg/s) 15.97
(kg/s) 5.59
(kg/s) 6.85
Diameter of Primary Zone (mm) 38
Diameter of Secondary Zone (mm) 10
Diameter of Dilution Holes (mm) 18
Number of Primary Nozzles 18
Number of Secondary Zones 164
Number of Dilution Holes 98
Length of Combustion Chamber (m) 0.195
Outer Diameter of Combustion Chamber (m) 0.239
Inner Diameter of Combustion Chamber (m) 0.15
56
6. High Pressure Turbine (HPT)
The High Pressure Turbine (HPT) uses one stage with a stator then rotor configuration. This component
rotates counterclockwise with the High Pressure Compressor. This is counter rotating with respect to
the Intermediate Shaft that is spinning clockwise. The HPT has an inlet temperature of 1557.4K and only
the stator requires a cooling circuit provided to the High Pressure Turbuine. Further information about
this component is given below.
Figure 38: HPT Isometric View
Hauenstein, Khan, Bohlemann
57
HUB
6.1 Aerodynamic Analysis
The following figures display the velocity triangles and their respective values at the hub mid and tip
sections at station two of the HPT.
Figure 39: HPT Hub Velocity Triangle
Table 41: HPT Hub Velocity Triangle Values
Station 2 3
Mabs 0.977 0.747
Mrel 0.651 1.28
U(m/s) 321.6 304.5
Vax(m/s) 278.4 292.3
V(m/s) 723.3 523.9
Vu(m/s) 667.6 434.8
W(m/s) 444.1 794.9
Wu(m/s) 346.0 739.3
α(deg) 67.4 56.1
β(deg) 51.2 68.4
Δαhub (deg) 123.45 Δβhub (deg) 119.61
58
MID
Figure 40: HPT Mid Velocity Triangle
Table 42: HPT Mid Velocity Triangle Values
Station 2 3
MREL 0.549 1.26
U(m/s) 354.7 365.4
VAX(m/s) 278.4 292.3
V(m/s) 666.2 465.5
VU(m/s) 605.2 362.3
W(m/s) 374.5 784.2
WU (m/s) 250.5 727.7
α(deg) 65.3 51.1
β(deg) 42.0 68.1
Δαmid 116.41
Δβmid 110.10
59
TIP
Table 43: HPT Tip Velocity Triangle Values
Important Conclusions and Observations
The velocity triangles and corresponding values above display the proper trends of absolute and relative
velocities across the rotor of the HPT. These trends show a decrease in absolute velocity while there is
an increase in relative velocity. Both Mach Number constraints, absolute and relative, have been met by
being lower than 1 and 1.45 respectively.
The alpha and beta constraints have been met by staying under 71˚.
Station 2 3
MREL 0.475 1.27
U(m/s) 387.8 426.2
VAX(m/s) 278.4 292.3
V(m/s) 619.6 426.5
VU(m/s) 553.5 310.6
W(m/s) 323.9 792.7
WU (m/s) 165.7 736.8
α(deg) 63.3 46.7
β(deg) 30.8 68.4
Δαtip 110.04
Δβtip 99.12
Figure 41: HPT Tip Velocity Triangle
60
6.2 Thermodynamic Analysis
The thermodynamic characteristics of the HPT are described below in the absolute frame of reference in
Table 44. The h-s diagram illustrated in Figure 42 also demonstrates these characteristics.
Figure 42: HPT h-s Diagram
Table 44: HPT h-s Diagram Values
Station 1 2 3
MABS 0.365 0.977 0.747
Po (Pa) 1068126.2 1061182.1 352724.3
P (Pa) 978385.8 588746.3 247270.6
To (K) 1558.1 1558.1 1226.7
T (K) 1524.5 1346.2 1123.2
ΔTo (K) --------------- --------------- 331.4
ho (J/kg) 1631565.3 1631565.3 1284500.6
h (J/kg) 1596423.0 1409678.1 1176138.8
Δho (J/kg) --------------- --------------- 347064.7
Δ so (J/kg*K) --------------- --------------- 37.4
Δ s (J/kg*K) --------------- --------------- 37.4
A (m2) 0.044 0.062 0.117
ρ (kg/m3) 2.47 1.68 0.85
61
Important Conclusions and Observations
As seen above in the table, both adiabatic expansion as well as expansion with work extraction
takes place across the HPT. This trend is seen as well in the area increase and density decrease. The
absolute Mach number, although high at station 2, does not exceed one which meets the criteria.
Looking at the static temperature trend, the stator is needed to be cooled from the station 15 of
the HPC. Due to the high acceleration of the flow across the stator, the static temperature was reduced
at the leading edge of the rotor to below 1350 K so no cooling was needed.
6.3 Geometric Analysis
The following figure display a meridional of the HPT as well as Table 45 and Table 46 which are
tabulated geometric values found during the design process.
Table 45: HPT Radii Values
Station 1 2 3
rM (m) 0.223 0.229 0.236
rH (m) 0.207 0.208 0.197
rT (m) 0.238 0.251 0.275
bavg (m) 0.037 0.061 0.079
Figure 43: HPT Meridional View
62
Table 46: HPT Airfoil Geometry Values
Stator Rotor
C Hub (m) 0.043 0.044
Stagger Hub (deg) 33.68 -8.62
Cax Hub (m) 0.036 0.044
C Mid (m) 0.046 0.040
Stagger Mid (deg) 32.65 -13.07
Cax Mid (m) 0.039 0.039
C Tip (m) 0.050 0.037
Stagger Tip (deg) 31.65 -18.80
Cax Tip (m) 0.043 0.035
Aspect Ratio 0.8 1.5
Taper Ratio 1.2 0.8
NOB 34 43
The following shows the stagger variation between hub mid and tip sections of the rotor. The stator
stagger overlay is not shown due to the low difference in stagger between the sections. As seen above
there is approximately only one degree difference in stagger.
Below in Table 47 are the key performance factors and other important values that are key to analyzing
the HPT.
Figure 44: Stagger of Rotor Blade
63
Table 47: Key Values for the HPT
Key Values
λ 2.6
Φ 0.8
TIT (K) 1558.1
Δho (J/kg) 347064.7
ηtt (%) 88.5
τoHPT 0.7873
πoHPT 0.3302
CP (J/kg*K) 1047.2
γ 1.33
RPM 14775
Degree of Reaction (hub) 0.636
Degree of Reaction (mid) 0.676
Degree of Reaction (tip) 0.722
Zweifel Coefficient 0.8
Important Conclusions and Observations
The performance factors in the table above including the work coefficient and flow coefficient are
reasonable values that are well within the given criteria. The degree of reaction (R) values given are also
within the given limits of above 0.1 and below 1 and their trend from hub to tip is correct with the
highest being at the tip.
64
7. Intermediate Pressure Turbine (IPT)
The Intermediate Pressure Turbine is spinning in the clockwise direction, opposite of the HPT allowing it
to utilize the swirl from the HPT rotor and use a single rotor configuration with no stator. This
configuration is used due to the small amount of work the IPC requires.
Figure 45: Isometric View of IPT
Hauenstein, Khan, Bohlemann
65
Hub
7.1 Aerodynamic Analysis
Below are the velocity triangles showing the exit of the HPT and the inlet of the IPT at hub mid and tip.
Take note in the ways the velocity vectors are directed representing the counter rotation. The values for
these triangles can be found on the following page.
Tip
Mid
Figure 47: HPT-IPT Hub Velocity Triangle Figure 46: HPT-IPT Mid Velocity Triangle
Figure 48: HPT-IPT Tip Velocity Triangle
66
Table 48: HPT-IPT Velocity Triangle Values
Hub Mid Tip
U (m/s) 304.5 365.4 426.2
U' (m/s) 284.5 341.6 398.7
Vax (m/s) 292.3 292.3 292.3
V (m/s) 523.9 465.5 426.5
Vu (m/s) 434.8 362.3 310.6
W (m/s) 794.9 784.2 792.7
Wu (m/s) 739.3 727.7 736.8
W' (m/s) 407.7 292.7 292.7
Wu' (m/s) 150.2 20.4 88.6
α (deg) 56.1 51.1 46.7
β (deg) 68.4 68.1 68.4
β' (deg) 27.2 3.99 16.9
The velocity triangles and tables of values below will show the aerodynamic trends across the IPT rotor.
It is important to note that the inlet values of relative velocity and beta angles are the same as the prime
values shown in the above triangle.
67
Table 49: IPT Hub Velocity Triangle Values
Station 1 2
MREL 0.654 0.722
U (m/s) 284.5 289.5
VAX(m/s) 292.0 318.3
V(m/s) 523.6 335.0
VU(m/s) 434.7 104.6
W(m/s) 407.7 430.3
WU(m/s) 150.2 394.1
α (deg) 56.1 18.2
β (deg) 27.2 51.1
ΔαHub (deg) 74.78
ΔβHub (deg) 78.99
HUB
Figure 49: IPT Hub Velocity Triangle
68
Table 50: IPT Mid Velocity Triangle Values
Station 1 2
MREL 0.470 0.915
U (m/s) 341.6 358.2
VAX(m/s) 292.0 318.3
V(m/s) 465.1 329.3
VU(m/s) 362.0 84.6
W(m/s) 292.7 545.3
WU(m/s) 20.4 442.7
α (deg) 51.1 14.9
β (deg) 3.99 54.3
ΔαMid(deg) 66.32
ΔβMid(deg) 59.05
MID
Figure 50: IPT Mid Velocity Triangle
69
Table 51: IPT Tip Velocity Triangle Values
Important Conclusions and Observations
As seen in the triangles representing counter rotation and the corresponding data table shows the exit
alpha of the HPT is 51˚ at the mid. With this high alpha angle, the IPT rotor is able to take advantage of
the swirl from the HPT allowing there to be no inlet stator needed. All velocity trends meet criteria for
this component as well as the angle requirements.
Station 1 2
MREL 0.793 0.893
U (m/s) 398.7 426.8
VAX(m/s) 292.0 318.3
V(m/s) 426.0 326.1
VU(m/s) 310.1 71.0
W(m/s) 494.2 532.4
WU(m/s) 88.6 497.8
α (deg) 46.7 12.6
β (deg) 16.9 57.4
ΔαTip(deg) 59.54
ΔβTip(deg) 41.34
Figure 51: IPT Tip Velocity Triangle
TIP
70
7.2 Thermodynamic Analysis
Below in Figure 52 and Table 52 represents the absolute frame of reference thermodynamic
characteristics of the IPT.
Table 52: IPT h-s Diagram Values
Station 1 2
MABS 0.746 0.553
PO (Pa) 352686.4 200945.0
P (Pa) 247421.8 164831.6
TO (K) 1226.6 1079.6
T (K) 1123.3 1027.8
ΔTO (K) ----------------- 146.7
hO (J/kg) 1284471.4 1130522.2
h (J/kg) 1176321.7 1076295.8
ΔhO (J/kg) ----------------- 153652.9
Δ sO (J/kg*K) ----------------- 15.3
Δ s (J/kg*K) ----------------- 15.3
A (m2) 0.117 0.148
ρ (kg/m3) 0.85 0.62
Figure 52: IPT h-s Diagram
71
Important Conclusions and Observations
As seen above in the table, both adiabatic expansion as well as expansion with work extraction
takes place across the IPT. This trend is seen as well in the area increase and density decrease. The
absolute Mach number, although high at station 2, does not exceed one which meets the criteria. This
single rotor stage requires no cooling due to an inlet temperature below 1350 K.
7.3 Geometric Analysis
Below displays the meridional view of the IPT rotor along with corresponding tables containing
geometric data for the stage.
Figure 53: IPT Meridional View
72
Table 53: IPT Radii Values
Station 1 2
rm 0.236 0.248
rh 0.197 0.199
rt 0.276 0.296
bavg 0.088 0.097
Table 54: IPT Airfoil Values
C Hub (m) 0.045
Stagger Hub (deg) 11.930
Cax Hub (m) 0.044
C Mid (m) 0.044
Stagger Mid (deg) 25.149
Cax Mid (m) 0.039
C Tip (m) 0.044
Stagger Tip (deg) 37.144
Cax Tip (m) 0.035
Aspect Ratio 2
Taper Ratio 0.8
The following will show the stagger overlay of the blade to show the stagger of the hub mid and tip
sections.
Figure 54: IPT Stagger
73
Below in Table 55 are the key values and performance coefficients for the IPT that are used in analyzing
the component.
Table 55: IPT Key Values
λ 1.20
Φ 0.889
Δho (J/kg) 153949.2
ηtt (%) 92.00
τoHPT 0.880
πoHPT 0.570
Cp (J/kg*K) 1047.2
γ 1.33
RPM 13800
Degree of Reaction (hub) 0.323
Degree of Reaction (mid) 0.662
Degree of Reaction (tip) 0.717
Number of Rotors 47
Zweifel Coefficient 0.8
Important Conclusions and Observations
The above performance characteristics show a work coefficient of 1.2 which is low compared to the
range given between 2 and 2.8. This low work coefficient is due to the low power balance between the
IPT and IPC. The degree of reaction trend follows the correct trend of highest at tip and lowest at the
hub while also staying within the range of 0.1 to 1.
74
8. Power Turbine (PT)
The power turbine for the Unducted Propfan is a six-stage counter-rotating turbine. The flow is
introduced into the turbine through the high slope transition duct and an inlet guide vane (IGV). The exit
flow is turned axial through outlet guide vane (OGV). 12 turbine blade rows make up a six-stage power
turbine with each alternate row rotating in the opposite direction. Each stage has a pair of counter-
rotating rotors. As the turbine rotors rotate on a shaft, the turbine stators rings are unearthed and free
to move on a rotating cowling. This mechanism allows for stage-to stage counter-rotation throughout
the six-stage power turbine as illustrated in Figure 55. A total of six rotors rotating counter-clockwise are
connected to and operate the aft propfan while the other set of clockwise rotating turbine stators are
connected to and operate the front propfan.
Figure 55: Counter-rotating power turbine [AIAA-85-1190 The Unducted fan engine]
Figure 56: A 3D view of the power turbine (IGV/OGV-red; Rotors-blue; Unearthed Stators-black)
Khan, Bohlemann, Dantis, Palmer
75
Conventional Turbine vs Counter-rotating Turbine
In comparison to a conventional turbine, a counter-rotating turbine provides a comparable stage loading at lower rpm with a similar number of blade rows. This allows the counter-rotating power turbine to run the propfans at the required low rpm range of 1500-2000 within a reasonable no of six stages and without the requirement for a gearbox.
A comparative study between a conventional and a counter-rotating turbine stage highlighted the added thermodynamics advantages achieved through counter rotation. These are listed in Table 56 along with the respective stage configuration represented in Figure 57 and Figure 58
Figure 57: Conventional Stage
Figure 58: Counter-Rotating Stage
Table 56: Counter-rotating Stage vs. Conventional Stage
Conventional Stage Counter-Rotating Stage
Efficiency (%) 89 89
Work Coefficient 2.78 2.58
Delta h (J/kg) 27912 55960
Pressure Ratio 1.14 1.30
Temp Ratio 1.03 1.06
76
As a stator is replaced by a rotor rotating in the opposite direction, the counter-rotating stage provides a higher capacity to do work with a comparatively similar work coefficient to that of a conventional Stage. It also provides a higher temperature and pressure ratio across the stage. Thus, counter-rotation allows for an optimum turbine design required to operate the Propfans.
Turbine Power Requirement
The power required from the turbine to operate the Propfans is listed in Table 57. The clockwise rotating rotors running the front fan will be referred to as Stators from this point onwards for the sake of simplicity and clarification.
Table 57: Power Requirement
Fan 1 Fan2
RPM 1708 1855
Power(HP) 6319 6311
Stators Rotors
η % 96
Mass flow rate(kg/s) 29.07 29.07
Δh(J/kg) 168856 168653
The work split across the rotors and stators for the power turbine is as follows.
Figure 59: Work Split across the Power Turbine
Blade rows, moving from front to aft, constitute a higher diameter and therefore perform more work.
The load factor on each rotating blade across PT is demonstrated through its work coefficient in Figure
60.
27700
27800
27900
28000
28100
28200
28300
28400
1 2 3 4 5 6
Tota
l En
thal
py
(kg/
J)
Stages
Work split across PT
Rotors
Stators
77
Figure 60: Work Coefficient of Rotors and Stators across the Power Turbine
The work coefficient for the rotors and stators increases progressing to the later stages. The rotors have
an average work coefficient of 2.37 compared to the stators with an average work coefficient of 2.79.
This difference in loadings can be attributed to the difference in component RPMs based on propfan
requirement where the stators are generating a higher amount of work with lower RPMs than the rotors
as seen in Table 57.
The results from thermodynamics, aerodynamic and geometric analysis for the Power Turbine Design are described in the following sections.
8.1 Aerodynamic Analysis
The power turbine with its six stages plus an IGV and OGV, is comprised of 15 stations. The aerodynamic
characteristics in the absolute and relative FoR for the power turbine at its Aero/Thermo stations 2, 3
and 4 are listed in Table 58, Table 59 and Table 60. These stages are a good representation of the
characteristics throughout the PT. The velocity triangles illustrated Figure 61 in demonstrates these
characteristics.
0
0.5
1
1.5
2
2.5
3
R1 S1 R2 S2 R3 S3 R4 S4 R5 S5 R6 S6
Wo
rk C
oe
ffic
en
t
PT Components
Work Coefficient across PT
Rotor
Stator
78
Table 58: PT Aerodynamic characteristics at TIP
Rotor 1 Stator 1
Station 2 3TE
3LE
4
Vax
(m/s) 105.11 107.22 107.22 108.82
V(m/s) 168.05 161.38 161.38 161.47
Vu(m/s) 131.12 120.62 120.62 119.30
W(m/s) 107.10 255.43 107.22 264.52
Wu(m/s) 20.56 231.84 -1.18 241.10
U(m/s) 110.56 111.22 121.80 121.80
α(°) 51.28 48.37 48.37 47.63
β(°) 11.07 65.18 -0.63 65.71
Mar 0.18 0.43
Ma 0.28 0.27
Δ β(°) 76.25 65.08
Stagger(°) 27.05 33.17
Table 59: PT Aerodynamic characteristics at MID
Stator 1 Rotor 1
Station 2 3TE
3LE
4
Vax
(m/s) 105.11 107.22 107.22 108.82
V(m/s) 178.83 162.07 162.07 163.31
Vu(m/s) 144.68 133.88 133.88 133.45
W(m/s) 114.13 257.47 110.09 265.65
Wu(m/s) 44.47 234.09 25.00 242.33
U(m/s) 100.20 100.20 108.88 108.88
α(°) 54.00 48.58 48.58 48.22
β(°) 22.89 55.86 13.12 55.98
Mar 0.19 0.43
Ma 0.29 0.27
Δ β(°) 78.75 69.10
Stagger(°) 16.5 21.43
79
Table 60: PT Aerodynamic characteristics at HUB
Rotor 1 Stator 1
Station 2 3TE
3LE
4
Vax
(m/s) 105.11 107.22 107.22 108.82
V(m/s) 192.58 184.72 184.72 186.47
Vu(m/s) 161.36 150.42 150.42 151.42
W(m/s) 127.14 262.50 120.25 270.26
Wu(m/s) 71.52 239.61 54.46 247.38
U(m/s) 89.84 89.18 95.96 95.96
α(°) 56.92 54.52 54.52 54.30
β(°) 34.23 65.89 26.93 66.26
Mar 0.21 0.44
Ma 0.32 0.31
Δ β(°) 100.13 93.18
Stagger(°) 15.83 19.56
80
Figure 61: Velocity Triangle at Hub, Mid, and Tip; Rotor 1 Rotating Counter-Clockwise, Stator 1 Rotating Clockwise
81
Figure 61 demonstrates an increasing stagger flow leaving the IGV and entering the CCW rotating rotor
at station 2. Swirl is added to the flow in the relative FoR (W) and removed in the absolute FoR(V). This
flow enters CW rotating Stator 1 at station 3. The flow in the relative FoR (WLE) attains a new direction
due to counter-rotation and swirl is induced to it across the stator.
The increase of V (V3LE < V4) across Stator 1 (Station 3TE-4) in spite of the expected decrease
demonstrates the additive effect of counter-rotation as the V continues to increase through the PT and
eventually contributed to the thrust from the core.
The aero/thermo hub for a stator indicated in Figure 61 corresponds to its geometric tip and vice versa
since its rotating on the cowling. Regardless of the geometry, the stagger and the camber follow the
expected trend from the aero/thermo hub to tip; the stagger increases and the camber decreases from
hub to tip.
Figure 62: Stack for the Power Turbine Rotor.
Figure 63: Stack for the Power Turbine Stator
82
The aerodynamic trend across the PT is demonstrated in Figure 64
Figure 64: Velocity Distribution across the Power Turbine
The flow is accelerating throughout PT in the axial direction, the absolute and the relative FoR. Ma_Wo
represents relative velocity(W) before the effect of counter-rotation, and Ma_Wc represent W after
counter-rotation as W attains a new direction.
The highest Mach in the relative FoR is 0.59 and therefore within the design criteria of 1.45 Mach.
This acceleration of flow across the PT is characterized through the increase in flow coefficient across
the PT as illustrated in Figure 65.
Figure 65: Flow Coefficient across the Power Turbine
0
0.1
0.2
0.3
0.4
0.5
0.6
R1 S1 R2 S2 R3 S3 R4 S4 R5 S5 R6 S6
Mac
h N
um
be
r
PT Components
Velocity Distribution across PT
Ma_Vax
Ma_Wc
Ma_V
Ma_Wo
0.8
0.85
0.9
0.95
1
1.05
1.1
1.15
1.2
1.25
1.3
R1 S1 R2 S2 R3 S3 R4 S4 R5 S5 R6 S6
Flo
w C
oe
ffic
ien
t
PT Components
Flow Coefficientacross PT
83
The flow coefficient generally increases across the turbine. The rotors have a lower coefficient
compared to the stators due to lower RPMs for comparatively the same amount of work.
The Degree of reaction for the PT rotors and stators is illustrated in Figure 66
Figure 66: Degree of Reaction for the Power Turbine Components
The reactions are significantly high and positive indicating a decrease in pressure throughout the turbine. There is no danger of pressure rise. With the exception of R1, the components follow an expected trend of a decrease in reaction from tip to hub.
8.2 Thermodynamic Analysis The thermodynamic characteristics in the absolute and relative FoR for the power turbine at its
Aero/Thermo stations 1, 2, 3 and 4 are listed in Table 61. The h-s diagrams illustrated in Figure 68 and
Figure 69 demonstrate these characteristics.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
R1 S1 R2 S2 R3 S3 R4 S4 R5 S5 R6 S6
DO
R
PT Components
Degree of Reaction
HUB Reaction
MID Reaction
TIP Reaction
84
Figure 67: Meridional View of for Station 1, 2, 3 and 4
Figure 68: h-s Diagram UDF rotor in Relative FoR
85
Figure 69: h-s Diagram UDF rotor in Absolute FoR
Table 61: Thermodynamic Characteristics across Station 1, 2, 3 and 4
Station P0 P T
0 T h0 h V W
1 198669.2 194928.8 1078.9 1073.8 1116686.2 1124372.3 103.1 2 198483.5 187401.3 1078.9 1063.6 1116686.2 1113697.3 178.8 3 177254.5 168891.4 1052.2 1039.7 1088774.1 1088641.8 162.1 4 157815.5 150064.0 1025.6 1012.8 1060828.3 1060493.7 163.3 2r 191857.85 187401.3 1069.8 1063.6 1120210.6 1113697.3 114.1
3rTE 190591.84 168891.4 1071.3 1039.7 1121787.36 1088641.8 257.4
3rLE 172712.68 168891.4 1045.4 1039.7 1094701.99 1088641.8 110.0 4 171223.92 150064.0 1046.5 1012.8 1095777.57 1060493.7 265.6 Figure 69 demonstrates the IGV, Rotor 1 and Stator 1 in an absolute FoR. The IGV exhibits adiabatic
expansion with no work and thus a Δh0 = 0. Rotor 1 and Stator 1 exhibit adiabatic expansion with work
done across Rotor 1 being h03 - h02 and Stator 1 being h04 - h03.
86
Figure 68 demonstrates Rotor 1 and Stator 1 in a relative FoR. Each blade behaves like a stator and
exhibits adiabatic expansion with h02r=h03rTE and h03rLE=h04r . h03rLE < h03rTE and W3LE < W3TE exemplifies
counter-rotation in the PT where W3LE leading into Stator1 acquires a new direction and a lower
magnitude compared to W3TE leaving rotor 1. The temperature and pressure distribution across the PT is described in Figure 70 and Figure 71. The pressure ratio across the PT is 0.2 and the temperature ratio in 0.7.
Figure 70: Pressure Variation across Power Turbine
Figure 71: Temperature Variation across the Power Turbine
As expected, the temperatures and pressures across PT decrease from front to aft of the engine with the
total pressures and temperatures higher than the static pressures and temperatures.
0
50000
100000
150000
200000
250000In
let
IGV R1 S1 R2 S2 R3 S3 R4 S4 R5 S5 R6 S6
OG
V
Pre
ssu
re(P
a)
PT Components
Pressure Variation across PT
P0
P
0
200
400
600
800
1000
1200
Inle
t
IGV R1 S1 R2 S2 R3 S3 R4 S4 R5 S5 R6 S6
OG
V
Tem
pe
ratu
re(K
)
PT Components
Temperature Variation across PT
T0
T
87
8.3 Geometric Analysis The geometric characteristics of the power turbine are listed in Table 62 and Table 63 and demonstrated
in the detailed meridional view illustrated in Figure 72. The PT’s areas expand from front to aft with
constant mid radius.
Table 62: Geometry per Station across the Power Turbine
Station Area rh rm rt 1 0.404 0.503 0.560 0.618 2 0.408 0.502 0.560 0.618 3 0.434 0.499 0.560 0.622 4 0.468 0.494 0.561 0.627 5 0.522 0.486 0.561 0.635 6 0.559 0.481 0.561 0.640 7 0.615 0.473 0.561 0.648 8 0.671 0.465 0.561 0.656 9 0.736 0.456 0.561 0.665
10 0.807 0.446 0.561 0.675 11 0.900 0.433 0.561 0.689 12 0.992 0.420 0.561 0.702 13 1.068 0.410 0.561 0.712 14 1.158 0.397 0.561 0.725 15 1.267 0.381 0.561 0.741
88
Rotor
Stator IGV/OGV
Table 63: Geometry per Component across the Power Turbine
Avg Span Mid Chord AR TR IGV 0.115 0.052 2.2 1.2 R1 0.120 0.034 3.5 0.8 S1 0.128 0.037 3.5 1.2 R2 0.141 0.040 3.5 0.8 S2 0.153 0.055 2.8 1.2 R3 0.167 0.048 3.5 0.8 S3 0.183 0.052 3.5 1.2 R4 0.200 0.057 3.5 0.8 S4 0.219 0.063 3.5 1.2 R5 0.242 0.081 3 0.8 S5 0.268 0.077 3.5 1.2 R6 0.292 0.083 3.5 0.8 S6 0.316 0.083 3.8 1.2
OGV 0.344 0.132 2.6 1.2
The merdional view shows the flow entering the IGV, followed by 12 rows of counter-rotating rotors and
unearthed stators and exiting through the OGV to the exhaust nozzle.
Figure 72: The Meridional Flow Path of the Power Turbine
89
The number of blades for the Power Turbine is listed in Figure 73.
Figure 73: The Number of Blades across the Power turbine
82 90
102
86 94
74 72 62 60
66
50 44 46
70
0
20
40
60
80
100
120
IGV R1 S1 R2 S2 R3 S3 R4 S4 R5 S5 R6 S6 OGV
No
of
bla
de
s
PT Components
No of blades
90
9. Propfan
Most of the propulsive power for this engine comes from the two counter-rotating profans in the rear of the engine. The propfans have the ability to change their pitch through a computer controlled hydraulic system which alters the pitch of the blade to ensure maximum thrust generation at different flight conditions. The two sets of propfan blades are each attached to the corresponding components in the powerturbine. These powerturbines spin the propfan blades. Both propfan and the corresponding stages of the powerturbine spin at the same RPM.
Figure 74: Propfan Isometric View
The results from thermodynamic, aerodynamic and geometric analysis for the fan design are described and more details of the engine are given in following sections.
Bohlemann, Khan, Hauenstein
91
9.1. Geometric Analysis
When designing the propfan blades it is very important to select the correct airfoil as this will allow for high performance. For this design the Lockheed C-141 BL761.11 was chosen for its high CLmax angle as well as its low camber and thin shape. The characteristics of the airfoil chosen are listed below in Table 64.
Table 64: Propfan Airfoil Data
The low camber and thin characteristic is expected for a high speed airfoil. The CLmax angle of attack is
very important in respect to maximizing thrust. Thrust for this airfoil is highest at the CLmax value of 15˚.
Thus, for the propfan design it is important to attempt to keep angle of attack as close as possible to 15˚
to maximize thrust generation.
The chord lengths chosen for the propfan blade designs were reverse engineered from the GE-36. The
same chord values were used for propfan 1 and propfan 2. The chord lengths are shown in the Table 65
below in radial locations (r/R) intervals of 10%.
Airfoil Data
Thickness: 10.50%
Camber: 1.80%
Trailing edge angle: 18.3o
Lower flatness: 70.30%
Leading edge radius: 2.30%
Max CL: 1.15
Max CL angle: 15
o
Max L/D: 41.709
Max L/D angle: 6.5
Max L/D CL: 0.995
Stall angle: 6.5
Zero-lift angle: -2o
Figure 75: Propfan Airfoil
92
Table 65: Radial Variation for Propfan
r/R Propfan 1 & 2
Chord (m)
βP1
(deg)
βP2
(deg)
αP1
(deg)
αP1
(deg)
0.0 0.427 97 99 --- ---
0.1 0.447 98 99 13.3 14.8
0.2 0.447 93 95 13.7 14.9
0.3 0.447 89 91 13.8 15.0
0.4 0.439 85 87 13.9 15.0
0.5 0.419 82 84 13.9 15.0
0.6 0.391 78 80 13.9 14.9
0.7 0.363 75 77 13.7 14.8
0.8 0.334 72 74 13.4 14.4
0.9 0.286 69 71 13.3 14.3
1.0 0.193 65 67 13.1 14.0
The above values are set at cruise conditions. The pitch angle, the angle between axis of rotation and
the chord line, is determined based on the angle of attack, meaning the pitch angle is adjusted in order
to ensure angle of attack is at the desired value. In the table the corresponding angle of attacks are
given, and it can be observed that they are all close to their max allowed value of 15˚. If the angle of
attack exceeds 15˚, the lift is cut off and the propfan blade now experiences a reduction in its lift ability
which negatively impacts the thrust produced.
Table 66: Propfan Key Geometric Values
The tip speed for propfan 1 and 2 are mach 1.1 and 1.2, respectively. These speeds are obviously too
high therefore sweep is introduced to the blades, as can be seen in the above tables. This is done for
noise reductions. Tip speeds are the higher than the rest of the blade speeds. When these tip speeds
approach the critical Mach number, flow issues arise and these flow issues and shock formation cause
the creation of intense unwanted noise and vibration. To minimize the noise the blades are swept back
to allow for these tips to have high speeds but not all the noise and flow problems that come with high
speed. It is important to note the amount of sweep for the blades was determined at cruise condition,
because in this flight condition the tips speeds were the highest.
Key Values Propfan 1 Propfan 2
NOB 13 11
Blade Height (m) 1.197 1.151
Fan Diameter (m) 2.394 2.302
Sweep 45° 48°
93
Also it is important to note that the diameter of propfan 2 is slightly smaller than propfan 1. This
difference in diameter helps in reducing noise. A significant amount of the noise generated in an
unducted fan design engine comes from the viscous interactions between the propfan blades. Basically
when the front propfan vortices interact with the aft propfan, noise is generated, and to avoid excessive
interaction between the vortices, a simple solution of reducing the diameter of the aft causes a
reduction in the interaction of the two. The diameter of the GE-36 engine fan blades is about 7.7ft, and
the engine design in this report is about 7.8ft.
The GE-36 Unducted Fan was used as a basis for this engine design, but with respect to the number of
blades based on research this design was modernized. It has been shown to reduce to noise, if the
number of blades is different, the resonance affect is reduced. More experimental data needs to be
gathered to completely verify this, but it has been shown to put more blades in the front propfan to
reduce noise. Thus, based on research showing a 12x10 configuration, it was decided to go with a 13x11
configuration to ensure sufficient thrust without exceeding tip speeds by having to increase RPM too
much.
*All lengths are in meters, and they are axial lengths not true lengths*
Figure 76: Propfan 1 snd 2
94
Figure 77: Pitch Angles across Flight Conditions
The pitch trend is correct as in propellers the pitch angle decreases from hub to tip to keep the angle of
attack mostly constant at it CLmax angle across the blade to maximize thrust.
50
60
70
80
90
100
110
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Pit
ch A
ngl
e (
de
g)
Radial Location r/R
Pitch Angle (Blade Twist)-Cruise Propfan 1
Propfan 2
30
40
50
60
70
80
90
100
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Pit
ch A
ngl
e (
de
g)
Radial Location r/R
Pitch Angle- TO Propfan 1
Propfan 2
20
30
40
50
60
70
80
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Pit
ch A
ngl
e (
de
g)
Radial Location r/R
Pitch Angle - SLS
Propfan 1
Propfan 2
95
Figure 78: Angle of Attack Across Flight Conditions
The angle of attack is mostly constant in all stages of flight. In the TO and SLS stages the angle is not
completely stable especially in the sections close to the hub, which is still acceptable, since when
analyzing propellers the sections close to hub are often ignored since they contribute very little to the
thrust.
0
5
10
15
20
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Ao
A (
de
g)
Radial Location r/R
Angle of Attack -Cruise
Propfan 1
Propfan 2
0
5
10
15
20
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Ao
A (
de
g)
Radial Location r/R
Angle of Attack -TO
Propfan 1
Propfan 2
0
5
10
15
20
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Ao
A (
de
g)
Radial Location r/R
Angle of Attack -SLS
Propfan 1
Propfan 2
96
Figure 79: Advance Angle Across Flight Conditions
The advance angle for all stages of flight share the same trend of decreasing from hub to tip. This makes
sense as pitch angle is decreasing while angle of attack remains almost constant, therefore advance
angle has to decrease as a well.
0
10
20
30
40
50
60
70
80
90
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Ad
van
ce A
ngl
e (
de
g)
Radial Station r/R
Advance Angle - Crz
Propfan 1
Propfan 2
0
10
20
30
40
50
60
70
80
90
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Ad
van
ce A
ngl
e (
de
g)
Radial Station r/R
Advance Angle - TO
Propfan 1
Propfan 2
0
10
20
30
40
50
60
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Ad
van
ce A
ngl
e (
de
g)
Radial Station r/R
Advance Angle - SLS
Propfan 1
Propfan 2
97
9.2. Aerodynamic Analysis
The results for the Aerodynamic analysis for both propfan 1 and propfan 2 are analyzed below. The analysis is completed at 80% chord length, since propellers are usually analyzed at about 70-80% chord length. This is done since most thrust is generated towards the tips of propellers and at the hub a lot of aerodynamic flow problems occur and very little thrust is generated in this region; therefore propellers are analyzed on average at 75% chord. The values obtained in the data analysis where taken at 10% intervals, thus 80% was the reasonable choice. The aerodynamic characteristics for the propfan at cruise flight condition are shown below in Table 67.
Figure 80: Propfan Cruise Velocity Triangle
98
Table 67: Propfan Cruise Velocity Triangle Values
Important Observations and Conclusions
Advance angle, φp , is the angle formed between the rotation axis, and a tangent to the blade helix. The advance angle of the two blades is different as expected since the RPM and Velocity of the two propfans are different. The angle of attack, αp, is seen to be close to 15˚ which is what is desired to maximize thrust.
The effects of counter-rotation are also exhibited. The increase of V (V1 < V2) across Rotor 1 (Station 1 – 2) describes swirl induction. Employing counter-rotation in propfan 2 (Station 3 - 4 ), this swirl is expelled as V is turned axial again, without the expected reduction in V (V4 > V3) typical of swirl expulsion. This demonstrates how counter-rotation recovers exit swirl between blades and converts this to thrust.
Station 1 2 3 4
Vax
(m/s) 253.1 279.5 279.5 302.2
Vu
(m/s) ------- 60.3 60.3 5.3
V (m/s) 253.1 286.0 286.0 302.2
M 0.85 0.95 0.95 1.00
Wu (m/s)
171.3 111.0 246.4 191.3
W (m/s) 305.6 300.7 372.6 357.7
MRelative 1.03 1.00 1.24 1.19
UP (m/s)
171.3 186.0 ------- -------
φP (deg)
55.9 48.6 ------- --------
αP (deg) 13.4 14.4 ------- --------
βP(deg) 71.9 73.8 ------- -------
β (deg) 34.1 21.6 41.4 32.3
α (deg) 0 12.2 12.2 1.0
99
9.3. Thermodynamic Analysis
Figure 81 demonstrates Propfan 1 and Propfan 2 in an absolute FoR. Each blade exhibits adiabatic
compression with work done across blade 1 being h02 - h01 and Rotor 2 being h04 - h03.
The figure below describes the thermo stations used to describe the flow through the propfans.
Figure 81: Propfan h-s Diagram
Figure 82: Propfan Aero/Thermo Stations
100
Table 68: Propfan Cruise Thermodynamic Values
Figure 83 demonstrates Propfan 1 and Propfan 2 in a relative FoR. Each blade behaves like a stator and
exhibits adiabatic compression with h01r=h02rTE and h02rLE=h04r . h02rTE < h02rLE and W2TE < W2LE
exemplifies counter-rotation in the propfan where W2LE leading into propfan 1 has a new direction and
a higher magnitude compared to W2LE leaving propfan 1. This phenomenon has a big part to play in the added work being done across a counter rotating fan compared to a conventional fan.
Station 1 2 3
Mach # 0.85 .938 1.01
γ 1.4 1.4 1.4
R (J/Kg*K) 287 287 287
Cp (J/Kg*K) 1004.5 1004.5 1004.5
P0 (Pa) 40198.1 44862.7 49990.0
P (Pa) 25064.0 25441.4 25962.1
T0 (K) 252.8 263.1 273.3
T (K) 220.9 223.7 226.6
h0 (J/Kg) 253957.7 264290.4 274525.8
ρ (Kg/m3
) 0.395 0.396 0.399
A (m2
) 4.50 4.33 4.17
V(m/s) 253.1 286.0 302.2
Propfan 1 Propfan 2
π0 1.116 1.114
τ0 1.041 1.039
Δh0 (J/Kg) 10332.6 10235.4
Δs0 (J/Kg*K) 8.55 7.11
Δs0 (J/Kg*K) 8.55 7.11
Total Δh0 (J/Kg) 20568.0
101
The figure below describes the thermo stations used to describe the flow through the propfans.
Figure 83: Propfan Relative h-s Diagram
Figure 84: Propfan Aero/Thermo Stations for Relative Frame of Reference
102
Table 69: Propfan Relative Thermodynamic Values
Table 70: Propfan Off Design Thermodynamic Values
Station 1 2 3
Before P1 Between P1 and P2 Aft P2
M 0.21 0.35 0.46 γ 1.4 1.4 1.4 R 287 287 287 cp 1004.5 1004.5 1004.5 Po 104522.4 125342.1 148080.8 P 101300.0 115146.7 128062.5 To 290.6 333.7 366.5 T 288.0 325.7 351.6 ho 291896.0 335196.4 368103.4 h 289296.0 327168.9 353140.9
ρ (kg/m3) 1.226 1.232 1.269
u (m/s) 72.1 126.7 173.0 A (m
2) 4.50 4.33 4.17
Loc P0
(Pa) P (Pa) T0
(K) T (K)
1 40198.1 25064.0 252.8 220.9
2 44862.7 25441.4 263.1 223.7
3 49990.0 25962.1 273.3 226.6
1r 48914.7 25064.0 267.4 220.9
2TEr 48331.9 25441.4 268.8 223.7
2LEr 66598.3 25441.4 292.8 223.7
3r 59626.3 25962.1 290.3 226.6
Loc h0 (J/Kg) h (J/Kg) Mach V(m/s) W(m/s)
1 253957.7 221894.1 0.85 253.1
2 264290.4 224748.7 0.95 286.0
3 274525.8 227659.1 1.00 302.2
1r 268604.8 221894.1 1.03
305.6
2TEr 269975.2 224748.7 1.00 300.7
2LEr 294164.0 224748.7 1.24 372.6
3r 291624.6 227659.1 1.19 357.7
103
Table 71: Key Propfan Stage Thermodynamic Values- Off Design
In the table above, as in the Cruise Thermo values, Cp is constant. It is determined that Cp is constant as
there a very small temperature change across the propfans.
9.4. Performance In the tables below some key performance characteristics of each propfan in different flight conditions
are listed.
Table 72: Propfan Cruise Performance
Summary-Cruise Propfan 1 Propfan 2
Blade Height (m) 1.197 1.152
RPM 1708 1855
NOB 13 11
Velocity (m/s) 253.14 278.19
AF/blade 187 195
CT 0.19 0.17
CP 0.89 0.84
CQ 0.14 0.13
J 3.71 3.91
η PROP
0.78 0.81
P (HP) 6319.34 6311.68
P (Watts) 4712330.02 4706617.82
∆ho (J/Kg) 10332.63 10235.39
π0 1.116 1.114
mass flow (kg/s) 456.1 459.8
T(lb) 3278 3084
Total ∆ho (J/Kg) 20568
Total P (HP) 12631
Total T(lb) 6362
Propfan 1 Propfan 2
π0 1.20 1.18
τ0 1.15 1.10
Δh0 (J/Kg) 43300.4 32907.0
Δs0 (J/Kg*K) 86.8 46.2
Δs0 (J/Kg*K) 86.8 46.2
Total Δh0 (J/Kg) 76207.5
104
In cruise condition the RPM was set to 1708 for propfan 1 and 1855 for propfan 2. These RPM were
chosen based on obtaining the correct amount of thrust as well as matching the HP of each propfan
since this was necessary for the power turbine. The velocity propfan two sees is the velocity which
comes off propfan 1. The activity factor for both blades is good, as they both are higher than the
comparable engine, GE-36 whose blades have an AF of 148. The advance ratio values of 3.71 and 3.91
are both values which represent a good forward motion of the engine for its revolution rate. The
pressure ratio across each propfan is relatively low compared to a fan but this is very characteristic for a
propeller style propulsive unit.
Table 73: Propfan Takeoff and SLS Performance
For TO and SLS condition, as can be seen in Figure 77 in the geometric section, the pitch of the propfans
were changed to acquire the desired thrust and power values. Pitch angle could not exceed 15˚ due to
the airfoil, thus, RPM was also changed to control the desired thrust and power.
Summary-SLS Propfan 1 Propfan 2
Blade Height (m) 1.197 1.152
RPM 2000 2010
NOB 13 11
Velocity (m/s) 0 20.60
AF/blade 187 195
CT 0.16 0.16
CP 0.28 0.33
CQ 0.044 0.053
J 0.00 0.27
η PROP
0.00 0.13
P (HP) 10305.7 10280.0
P (Watts) 7684995.9 7665804.8
∆ho (J/Kg) 132493.1 92213.3
mass flow (kg/s) 58.0 83.1
T(lb) 12791 10647
Total ∆ho (J/Kg) 224,706
Total P (HP) 20,586
Total T(lb) 23,439
Summary-TO Propfan 1 Propfan 2
Blade Height (m) 1.197 1.152
RPM 1610 1690
NOB 13 11
Velocity (m/s) 72 119.6
AF/blade 187 195
CT 0.16 0.14
CP 0.50 0.52
CQ 0.078 0.083
J 1.12 1.84
η PROP
.36 0.5
P (HP) 9534.0 9662.7
P (Watts) 7109489.5 7205480.2
∆ho (J/Kg) 43300.4 32907.0
mass flow (kg/s) 164.2 219
T(lb) 7958.1 6754.9
Total ∆ho (J/Kg) 76207.5
Total P (HP) 19196.7
Total T(lb) 14713
105
10. Inlet
The goal of the Inlet is to allow the appropriate amount of upstream air to be capture and swallowed by
the engine while minimizing inlet lip losses. Similarly, the goal of the Diffuser is to minimize viscous
losses in between the inlet lip and the first stage of the IPC by allowing the air to decelerate smoothly
from one point to the other. Both the Inlet and Diffuser were designed simultaneously using CATIA
V5R20 educational software. The table below shows the radius and area for the locations of interest.
Table 74: Areas at Locations of Interest Necessary for Inlet Design
Location Area (m2) Outer Diameter (m)
Takeoff Capture Area .735 .968
Cruise Capture Area .300 .618
Inlet .320 .639
Diffuser .328 .883
Finally, the start of the IPC was placed at a distance of .46m in the opposite direction from the capture
areas. A spline command in the Generative Shape Design workbench was used to connect each circle.
Two splines were used, one passing through what will be the top of the inlet and one passing through
what would be the bottom of the inlet. By manipulating the distance between inlet and capture area, a
smooth annulus was created by attempting to superimpose the cruise funnel on the takeoff funnel,
which allows for minimal losses at each flight condition.
Figure 85: Detailed Meridional Inlet View with Capture Cones
The flow through the diffuser can be described as adiabatic compression with no work. The process
from the Inlet to the IPC Entrance is modeled on the h-s Diagram in Figure 86 below.
Palmer
106
Table 75: Thermodynamics through Inlet Diffuser at Cruise
Inlet Diffuser
M 0.720 0.700
γ 1.4 1.4
R 287 287
cp (J/kg*K) 1004.5 1004.5
Po (Pa) 39796.1 39398.2
P (Pa) 28176.7 28403.2
To (K) 252.8 252.8
T (K) 229.1 230.3
ho (J/kg) 253957.7 253957.7
h (J/kg) 230100.9 231291.2
ρ (kg/m3) 0.429 0.430
u (m/s) 218.4 212.9
A (m2) 0.320 0.328
φ (m) 0.639 0.646
Δs (J/kg*K) 25.1 25.4
hO 1,2
h2
h1
s1 s2
PO1 PO2
P2
222
P1
1
2 ½ V1
2
½ V22
Figure 86: h-s Diagram of Flow through Inlet Diffuser
107
Table 76: Thermodynamics through Inlet Diffuser at Takeoff
Inlet Diffuser
M 0.582 0.575
γ 1.4 1.4
R 287 287
cp (J/kg*K) 1004.5 1004.5
Po (Pa) 103477.7 101925.6
P (Pa) 82286.1 81474.6
To (K) 290.6 290.6
T (K) 272.2 272.6
ho (J/kg) 291896.4 291896.4
h (J/kg) 273397.4 273804.1
ρ (kg/m3) 1.05 1.04
u (m/s) 192.35 190.22
A (m2) 0.32 0.33
φ (m) 0.64 0.65
Δs (J/kg*K) 2.88 4.34
108
11. Ducts
Engine ducts and diffusers are meant to guide the while at the same time accelerate or decelerate the
flow to an acceptable level for the next component. The engine has a total of 2 ducts. They range in size
based on their location throughout the engine. All Ducts were designed using CATIA V5R20 visualization
software. In order to design these components the components which they connected must be finalized
first. The duct length was determined by adjusting the spacing between the two components until the
steepest angle in the duct was no greater than 45° if the flow is accelerating or 30° if the flow is
decelerating.
11.1 High Pressure Compressor Exit Diffuser
11.1.1 Diffuser Thermodynamics
The flow from the HPC to the Combustion chamber is adiabatic compression with no work. Below is
pictured the enthalpy-entropy diagram and the table to the right of it shows all thermodynamic values
of interest.
Table 77: Diffuser Thermodynamics
Diffuser Entrance
Diffuser Exit
M 0.488 0.100
γ 1.38 1.38
R 287.0 287.0
cp (J/kg*K) 1042.3 1042.3
Po (Pa) 1072385.7 1084392.1
P (Pa) 912910.2 1076942.6
To (K) 719.7 719.7
T (K) 688.5 723.0
ho (J/kg) 750142.5 750142.5
h (J/kg) 717611.9 753533.4
ρ (kg/m3) 4.62 5.23
u (m/s) 255.1 53.5
A (m2) 0.02 0.10
φ (m) 0.18 0.36
Δs (J/kg*K) 77.73 3.48
Figure 87: HPC Exit Diffuser Thermodynamics and h-s Diagram
hO 1,2
h2
h1
s1 s2
PO1 PO2
P2
222
P1
1
2 ½ V1
2
½ V22
Palmer
109
11.1.2 Diffuser Geometry
Figure 88: HPC exit Diffuser Meridonial View
11.2 Intermediate Pressure Compressor/Power Turbine Duct
11.2.1 Duct Thermodynamics
The flow from the IPT to the PT is adiabatic compression with no work. The enthalpy-entropy diagram
pictured in Figure 89 depicts the process.
Table 78: IPT/PT Thermodynamics
Duct Entrance Duct Exit
M 0.538 0.169
γ 1.33 1.33
R 259.8 259.8
cp (J/kg*K) 1047.1 1047.1
Po (Pa) 200934.8 198614.6
P (Pa) 166466.2 194874.9
To (K) 1079.6 1079.6
T (K) 1030.3 1074.5
ho (J/kg) 1130414.1 1130414.1
h (J/kg) 1078844.7 1125095.1
ρ (kg/m3) 0.62 0.70
u (m/s) 321.2 103.1
A (m2) 0.15 0.40
φ (m) 0.44 0.72
Δs (J/kg*K) 12.47 3.02
Figure 89: IPT/PT Thermodynamics and h-s Diagram
hO 1,2
h2
h1
s1 s2
PO1 PO2
P2
222
P1
1
2 ½ V1
2
½ V22
110
11.2.2 Duct Geometry
Figure 90: Detailed Meridional View of IPT/PT Duct
The mean angle on the top surface of the duct is 28.9°. The bottom surface of the duct’s mean angle is
26.7°. These angles meet the design requirement of less than 30° in a duct with decelerating flow.
FLOW DIRECTION
111
12. Materials
A working engine is just an engine half done. To get the engine presentable and lucrative to the customer, the various components of the engine must prove that they will perform and exceed expectations in terms of life, durability and reliability. The materials used in the FUDD are top grade aerospace materials that guarantee long life and reliability of the engine.
12.1 Prop Fan
The propfan is about 13 feet in diameter and spins around 1800 rpm. The material that is chosen to create it should be strong enough to take rotational stresses and light enough to not add too much weight to the engine. The material chosen for the propfan is Titanium Aluminum Vanadium alloy (Ti-6Al-4V). The propfan is going to have a unique material design namely the titanium alloy sandwiches a titanium honeycomb structure. The main reason this is done is to save weight while not compromising on performance and reliability. Table 79 provides the composition of the alloy.
Table 79: Composition of Ti-6Al-4V
Element % Comp Element % Comp Element % Comp Element % Comp Element % Comp
Ti 90 Al 5.99 V 3.99 Fe >0.25 O >0.2
The thermal and mechanical properties of the alloy are represented in the table below.
Table 80: Properties of Ti-6Al-4V compared with standard Alumina
Criteria Ti-6Al-4V Alumina
Young’s Modulus (GPa) 119.3 70
Bulk Modulus (GPa) 153.1 76
Tensile Strength (GPa) 1.268 0.125
Endurance Limit (GPa) 0.64 0.172
Density (g/cc) 4.43 2.7
Melting Point (K) 1672 2277
Maximum Service Temp. (K) 623 2033
Thermal Expansion Coefficient ( strain/ K)
9.1 8.1
Thermal Conductivity (kW/m.K) 7.31 30
Titanium is relatively difficult to work with. However, the blade is created using patented Rolls Royce® technology which involves sandwiching and then air inflation till it reaches prime size. Rolls Royce® has used this technology on the Trent 900 and Trent 1000 already.
Dantis
112
12.2 Compressor The compressor consists of two parts namely the IPC and the HPC. The material used for both compressors is INCONEL® nickel-iron-chromium alloy 706. The alloy is a precipitation-hardenable alloy that provides high mechanical strength in combination with good fabrication ability. Table 81 provides the composition of the alloy.
Table 81: Composition of INCONEL® Alloy 706
Element % Comp. Element % Comp. Element % Comp. Element % Comp. Element % Comp.
Ni 39-44 Cr 14.5-17.5 Co 1 Nb 2.5-3.3 Ti 1.5-2
Al 0.4 C 0.06 Cu 0.3 Mn 0.35 Si 0.35
S 0.015 P 0.02 B 0.016 Fe rest
The INCONEL® alloy maintains its high strength and creep rupture resistance up to 980 K. This is due to the heat treatment process it undergoes during fabrication. Table 82 lists the mechanical and thermal properties of the alloy.
Table 82: Properties of INCONEL® Alloy 706 compared with standard Alumina
Criteria INCOLOY® Alloy 706 Alumina
Young’s Modulus (GPa) 165.5 70
Bulk Modulus (GPa) 170.3 76
Tensile Strength (GPa) 1.17 0.125
Endurance Limit (GPa) 0.74 0.172
Density (g/cc) 8 2.7
Melting Point (K) 1605 2277
Maximum Service Temp. (K) 1200 2033
Thermal Expansion Coefficient ( strain/ K)
12.5 8.1
Thermal Conductivity (kW/m.K) 13.5 30
As stated before, the alloy is highly machineable and is very easy to manufacture. It is easily available in the form of rods, plates, billets, wires, forgings and strips. Another reason to use a strong material for the compressor is to provide added strength and reliability to the blisk in the HPC.
12.3 Combustion Chamber
The combustion chamber is the hottest part of the engine and hence the material should be hard,
sturdy, heat resistant and durable. The material used for the combustion chamber is INCOLOY® alloy A-
286. It is an iron-nickel-chromium alloy with additions of molybdenum and titanium. The alloy maintains
good strength and exceptional oxidation resistance at high temperatures. The high strength and
excellent fabrication characteristics of INCOLOY® alloy A-286 make the alloy useful for various
components of aircraft and industrial gas turbines. It is also used for fastener applications in automotive
113
engine and manifold components subject to high levels of heat and stress and in the offshore oil and gas
industry.
Table 83: Composition of INCOLOY® alloy A-286
Element % Comp. Element % Comp. Element % Comp. Element % Comp.
Ni 24-27 Cr 13.5-16 Ti 1.9-2.35 Mo 1-1.5
V 0.1-0.5 C 0.08 Mn 2 Al 0.35
S 0.03 B 0.001-0.01 Si 1 Fe Rest
The table above consists of the composition of INCOLOY® alloy A-286. The high concentration of nickel and chromium adds strength and high temperature resistance to the alloy. Therefore the physical properties of the alloy are enhanced and perfect for the extreme conditions it is subjected to. The table below provides a brief synopsis of the mechanical and thermal properties of the alloy. To provide a good reference to the strength and durability of the alloy, the properties of Alumina are compared alongside as well.
Table 84: Properties of INCOLOY® alloy A-286 compared with standard Alumina
Criteria INCOLOY® Alloy A-286 Alumina
Young’s Modulus (GPa) 201 70
Bulk Modulus (GPa) 175.8 76
Tensile Strength (GPa) 0.897 0.125
Endurance Limit (GPa) 0.433 0.172
Density (g/cc) 7.94 2.7
Melting Point (K) 1700 2277
Maximum Service Temp. (K) 1433 2033
Thermal Expansion Coefficient ( strain/ K)
17.7 8.1
Thermal Conductivity (kW/m.K) 23.8 30
INCOLOY alloy A-286 is readily fabricated by standard procedures for stainless steels and nickel alloys. Therefore it is not difficult to manufacture is readily available in sheets, rods, bars and plates. This makes the alloy prime material for the combustion chamber based on our low TIT and the material’s durability.
12.3.1 Thermal Barrier Coating (TBC)
The thermal barrier coating chosen for the combustion chamber and the HPT blades is Yttria stabilized Zirconia (YSZ). YSZ is used industry wide for thermally protecting materials even when the temperature is beyond their melting range. It has been proven that a 150 μm application on the material surface can protect the material to up to 170 K beyond its melting point. The two main reasons YSZ is used today is because of its low thermal conductivity and high thermal expansion coefficient. These two reasons
114
contribute to an increased component life and durability. The following table highlights the mechanical and thermal properties of YSZ.
Table 85: Properties of YSZ
Criteria Value Criteria Value Criteria Value
Young’s Modulus (GPa)
208.91 Endurance Limit (GPa)
0.638 Max Service Temp. (K)
2455
Bulk Modulus (GPa)
128.93 Density (g/cc) 5.92 Thermal Expansion.
Coefficient ( strain/ K)
3.914
Tensile Strength (GPa)
0.71 Melting Point (K) 2972 Thermal
Conductivity (kW/m.K)
0.832
12.3.2 Anti Oxidation Coating
The anti oxidation coating used on the combustion chamber is Nickel Chromium Aluminum Yttrium alloy (NiCrAlY). NiCrAlY alloy has two main properties that make it a lucrative material. The first reason is because the coating acts as an adhesive and allows the TBC to successfully attach to the nickel alloy and secondly they prevent the oxidation of the nickel alloy in the event of TBC failure. This acts as a last resort before the nickel alloy fails.
12.4 Turbine The turbine section is divided in to 3 parts namely the HPT, the IPT and the PT. The material that is to be selected should be able to handle the high temperatures and stresses of gases coming out of the combustion chamber while it should be strong enough and well equipped to spin the propfan with relative ease. MAR-M-247 has a unique property of getting stronger and sturdier as it is subjected to increasing temperatures. Table 86 provides the chemical composition of MAR-M-247.
Table 86: Composition of MAR-M-247
Element % Comp. Element % Comp. Element % Comp. Element % Comp. Element % Comp.
Ni 59 W 10 Co 10 Cr 8.25 Al 5.5
Ta 3 Ti 1 Mo 0.7 Fe 0.5 B 0.015
The high concentration of nickel and chromium adds strength and high temperature resistance to the alloy. The material also has trace amounts of tantalum in it which helps reduce grain boundary which thereby increases grain size and decreases boundary cracking. Table 87 below provides a brief synopsis of the mechanical and thermal properties of the alloy. To provide a good reference to the strength and durability of the alloy, the properties of Alumina are compared alongside as well.
115
Table 87: Properties of MAR-M-247
Criteria MAR-M-247 Alumina
Young’s Modulus (GPa) 195.2 70
Bulk Modulus (GPa) 140 76
Tensile Strength (GPa) 1.758 0.125
Endurance Limit (GPa) 0.54 0.172
Density (g/cc) 8.44 2.7
Melting Point (K) 1733 2277
Maximum Service Temp. (K) 1238 2033
Thermal Expansion Coefficient ( strain/ K)
13.9 8.1
Thermal Conductivity (kW/m.K) 12 30
The HPT blades will also have a 150 μm coating of YSZ TBC with NiCrAlY anti oxidation coating to further protect them from the high temperature and gases from the combustion chamber. MAR-M-247 is the standard material used today for HPT and LPT blades. The manufacturing process has been set in stone for the past 20 years and therefore should not be hard to manufacture.
12.5 Duct and Diffuser The engine has a one duct and one diffuser. The duct connects the IPT to the PT while the diffuser connects the HPC to the combustion chamber. Based on the mechanical and thermal properties of the various components in the engine, the ideal material to make both the duct and the diffuser is INCONEL Alloy 706. The alloy is strong enough to handle the highly compressed air and relatively high temperature from the HPC with ease. Also, even though the temperature of the gases coming out of the IPT are slightly elevated when compared to the HPC and since the pressure is much lower, the alloy is an ideal candidate for both, the duct and the diffuser.
116
12.6 Inlet and Exit Cone The inlet cone is made of Hastelloy alloy X which is a solid solution strengthened super alloy. It is one of
the most widely used materials for fabricated parts in a gas turbine engine. The properties of Hastelloy
alloy X is elaborated in
Table 88 below.
Table 88: Mechanical and Thermal Properties of Hastelloy alloy X
Criteria Hastelloy alloy X Alumina
Young’s Modulus (GPa) 139 70
Bulk Modulus (GPa) 189 76
Tensile Strength (GPa) 0.703 0.125
Endurance Limit (GPa) 0.28 0.172
Density (g/cc) 8.22 2.7
Melting Point (K) 1628 2277
Maximum Service Temp. (K) 1422 2033
Thermal Expansion Coefficient ( strain/ K)
16.6 8.1
Thermal Conductivity (kW/m.K) 28.7 30
The alloy is highly machineable and is easily available in sheet and billet form. The inlet cone is coated with a polyurethane material to act as a protective layer.
117
1. References
1. CFM-CFM International. “LEAP56,LEAP-X, and Open Rotor” Jane’s Aero-Engines. : Jan. 31,2011
2. CFM. 2011. 30 January 2011 < http://www.cfm56.com/products/cfm56-7b>
3. Dickens, Tony, and Ivor Day. "The Design of Highly Loaded Axial Compressors." Journal of
Turbomachinery 133 (2011). Print.
4. U.S. DEPARTMENT OF TRANSPORTATION FEDERAL AVIATION ADMINISTRATION TYPE
CERTIFICATE DATA SHEET E00049EN (2007). Print.
5. “Full Scale Technology Demonstration of Modern Counterrotating Unducted Fan Engine
Concept” GE, NASA Contract No. NAS3-24210, CR-180867, December 1987
6. John E. Donelson, William T. Lewerenz, and Roger T. Durbin. “UHB Technology Validation – The
Final Step.” American Institue of Aeronautics and Astronautics. AIAA-88-2807. 1988.
7. Norris, Guy. “New-Generation GE Open Rotor and Regional Jet Engine Demo Efforts Planned”
Aviation Week. May 11,2008.
8. Peters, Andreas. “Assesment of Propfan Propulsion Systems for Reduced Environmental Impact”
Diplomarbeit (Thesis). RWTH Aachen University (Germany) and Massachusetts Institute of
Technology. January 2010
9. Turner, Aimme. “R-R achieves ‘very big step’ in open rotor Technology.” Flight International. Vol.
174. Issue 5160 (2008): pg 9
118
2. Appendix
Sample calculations
Compressor On Design
AERODYNAMICS
2 1
2
2
*(1 )
0.234*(1 0)
0.234m
m m m
m
m
r r r
r
r
3 2
3
3
*(1 )
0.234*(1 0)
0.234m
m m m
m
m
r r r
r
r
2 1
2
2
*(1 )
204.5* 1.10
184.1
ax ax ax
ax
ax
v v v
v
mvs
3 2
3
3
* 1
184.1*(1 0.08)
198.8
ax ax ax
ax
ax
v v v
v
mvs
1 12
2
2
2
77044 362.6* 21.5
362.6
191.0
o UU
U
U
h U VV
U
V
mVs
3 3 3
3
3
* tan( )
198.8* tan(11.5 )
40.4
U ax
o
U
U
V V
V
mVs
119
191.0 362.6
171.6
U U
U
U
W V U
W
mWs
1
1
tan
191.0tan
184.1
46.1
U
ax
o
V
V
1
1
tan
171.6tan
184.1
43.0
U
ax
o
W
V
2 2
2 2184.1 191.0
265.2
ax UV V V
V
mVs
2 2
22184.1 171.6
251.7
ax UW V W
W
mWs
THERMODYNAMICS
3 6 2 9 3
3 6 2 9 3
3.64 1.101*10 * 2.466*10 * 0.942*10 *
287 3.64 1.101*10 *407.5 2.466*10 *407.5 0.942*10 *407.5
1015.2*
p guess guess guess
p
p
C R T T T
C
JCkg K
1015.2
1015.2 287
1.394
p
p
C
C R
120
1
1 1 3
3
1
1.3938 1
1.3938
*
1011.2*1.69 1020.41020.4
.88
1011.2
1.183
avg
avg
p o p
p
tto
p
o
o
C CC
C
3 1
3
3
*
393.3*1.18
469.3
o o o
o
o
T T
T
T
3 3 3
3
3
*
1020.4*469.3
474721
o p o
o
o
h C T
h
Jhkg
3 1
474721 397677
77044
o o o
o
o
h h h
h
Jhkg
3 1
3
3
*
156035*1.69
263785
o o o
o
o
P P
P
P Pa
2
3
2 3
2
2
2
* *
2
.04*1.63*202.8263785
2
266085
guess
o o
o
o
VP P
P
P Pa
* *
265.2
1.392*287*431.6
.639
VM
R T
M
M
121
12
1.392
1.392 12
11 *
2
266085
1.392 11 *.639
2
202482
oPP
M
P
P Pa
2
2
2*
218.3431.0
2*1015.2
407.5
o
p
VT T
C
T
T K
3
*
202482
287*431.6
1.63
P
R T
kgm
.
2
*
30
1.63*184.1
.0997
ax
mA
V
A
A m
RADIAL EQUILIBRIUM
*
.234*191.0
.201
223.2
mid UmidUhub
hub
Uhub
Uhub
r VV
r
V
mVs
_ _
_ 184.1
ax hub ax mid
ax hub
V V
mVs
122
*
362.6.201*
.234
310.2
midhub hub
mid
hub
hub
UU r
r
U
mUs
OFF DESIGN AERODYNAMICS
3:Select
2 2OD DP
2 3
2
2
0 32.6
32.6
STATOR
o
CAMBER
22
2 2
2
2
tan( ) tan( )
380.9
tan(32.6) tan( 43)
242.5
ax
ax
ax
UV
V
mVs
.
3
3
3
*
30
3.28*.086
231.5
ax
guess
ax
ax
mV
A
V
mVs
OFF DESIGN THERMODYNAMICS
2 2 1 1
380.9*154.8 380.9*( 22.8)
67656
o U U
o
o
h U V U V
h
Jhkg
123
1 1
3
3
3
3
*
67656 1015.2*431.0
1024.0
493.4
o p o
o
p
o
o
h C TT
C
T
T K
3
1
493.4
431.0
1.145
oo
o
o
o
T
T
13 1 1
3
1.392
1.392 1
*
.88 1024.0*1.145 1015.2 1015.2
1024.0
1.526
avg
avgtt p o p p
o
p
o
o
C C C
C
Propfan Calculations
_
_
_
0 10.9
/ 0.2
0.12 2
0 0.42600.1 .006917 0.02865 0.06615 0.1183 0.1811 0.2514 0.3283 0.4074 0.4713
2 2
0.2072
no loss
no loss
no loss
T T
TT
r R
T
T
dC dC
dCdr drCdr
C
C
_1 ( 2 ) /
1 ( 2 0.2072) /13
0.95
no lossTB C NOB
B
B
124
_
_
_
1 1(( ( (1 )) / 2) (1 )
0.4260 0.4713((0.4260 (0.4260 (1 0.95)) / 2) (1 0.95)
1.0 0.9
0.0218
Tip
Tip Loss
Tip Loss
Tip Loss
T
T T T
T
T
dCC C C B B
dr
C
C
_ _
0.2072 0.0218
0.185
No Loss Tip LossT T T
T
T
C C C
C
C
2
3 2 2
( )
0.185 0.00073821( / ) 48.5 (702.52 / )
3269
TT C A R
T slug ft ft ft s
T lb
0 00 1
0
0
0
0
.9
/ .2
0.1
2 2
0 0.013890.1 0.00001305 0.0001081 0.0003769 0.0009138 0.001801 0.003131 0.005039 0.007664 0.01121
2 2
0.00372
Q Q
Q
Q
r R
Q
Q
dC dC
dCdr dr
C
dr
C
C
0 1
0.9
_
/ 0.1
_
_
0.1
2 2
0 0.38850.1 0.001018 0.007944 0.02603 0.05890 0.1072 0.1699 0.2465 0.3328 0.4114
2 2
0.1556
Qi Qi
Qi
Qi no loss
r R
Qi no loss
Qi no loss
dC dC
dCdr drC
dr
C
C
1
_
_
_
1
1 0.9505 0.3885
0.192
Qi
Qi Tip loss
Qi Tip loss
Qi Tip loss
dCC B
dr
C
C
125
_ _
0.1556 0.0192
0.1364
Qi Qi Qino loss tip loss
Qi
Qi
C C C
C
C
0
0.00372 0.1364
0.1401
Q Q Qi
Q
Q
C C C
C
C
2
2 0.1401
0.8803
p Q
p
p
C C
C
C
830 /
28.47 1/ 7.856
3.71
VJ
RPS D
ft sJ
s ft
J
0.1853.71
0.8803
0.78 78%
T
P
CJ
C
126
830.496 /3269
0.78
3480630.0( / ) 6328.4 4719100.7
VP T
ft sP lb
P ft lb s HP W
2
830.496 / 912.69 /
2
871.6 /
inlet exitavg
avg
avg
V VV
ft s ft sV
V ft s
.
2.
3
.
7.8560.0237( / ) 871.6 /
2
1001.3( / ) 455.1 /
avgm V A
ftm lb ft ft s
m lb s kg s
0 .
0
0
4719100.7
455.1( / )
10369.4 /
Ph
m
Wh
Kg s
h J Kg
22
2 2702.52 / 830.4 /
1087.7 /
1087.7 /
973.1 /
1.1
Tip forward
Tip
Tip
Tip
Tip
Tip
Tip
V R V
V ft s ft s
V ft s
VM
a
ft sM
ft s
M
127
3
0
4
0
4 4 4 4 4 4 4 4 4 4 4
100000
16
100000
16 4
16.82 17.61 17.61 17.61 17.29 16.50
0 0.1 0 0.2 0.1 0.3 0.2 0.4 0.3 0.5 0.4
100000 94.272 94.272 94.272 94.272 94.272 94.272
15.16 4
D
D
c r r
AF d
D R R
r
cR
AF
D
in in in in in in
in in in in in in
AF
4 4 4 4 4 4 4 4 4 439 14.28 13.17 11.26 7.61
0.6 0.5 0.7 0.6 0.8 0.7 0.9 0.8 1.0 0.9
94.272 94.272 94.272 94.272 94.272
187
in in in in in
in in in in in
AF