1
LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
Experimental Analysis of Wet Compression in Axial Compressor Stage
Laboratory of Thermal TurbomachinesNational Technical University of Athens
I. Roumeliotis K. Mathioudakis
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
Experimental Analysis of Wet Compression in Axial Experimental Analysis of Wet Compression in Axial Compressor StageCompressor Stage
Experimental Set-Up
Effect of Water Injection on Compressor Stage Aerodynamic Performance
Effect on Stage Power Consumption
Conclusions
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
First Stage of an Axial Compressor
Impaction Pin Nozzles (Mee Industries )
Experimental Set - Up
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
Experimental Set - Up
Lagrangian Framework
Droplet Evaporation Model
Meridional Flow Solver (2D)
Bellmouth Configuration
elongationbellmouthtrajectories
ImpingmentInitial Injection Position
Selected Injection Position
0.6 m
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
Experimental Set-Up
1. The flow rate of water
2. The pressure at nozzle manifold
3. Compressor Rotational Speed
4. Power of the Shaft
5. Ambient Conditions (pt0,Tt0,war0)
6. Compressor Inlet Conditions (pt1, ps1, Tt1, war1)
7. Inlet Flow Rate (Venturi)
8. Compressor Exit Conditions (pt3, ps3)
9. Oil Thermal Losses
Test-Rig Measurements
Nozzles manifold
microphone
Venturi static tapsstator rotor
throttle exit
Ps3 wall taps
pt1,Tt1,war1
Pt3 rake
Mechanical measurements
Pe GB
pt0,Tt0,war0
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
Experimental Set-Up
•Pressure Measurement: Potential Plugging of Pressure Holes and Connections due to Droplets
•Temperature Measurement: Droplets impingement at Temperature Sensors tend to Mask the Flow Temperature
•Humidity Measurement: Influencing the Magnitudes used for calculating the Stage Performance Characteristics
•Unstable Operation Determination: Hot Wire use in Droplet Laden Flow is not Plausible
Measurements Considerations
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
Experimental Set-Up
Pressure Measurements
0200400600800
10001200140016001800
0 10 20 30 40time(sec)
ps3-
p am
b(Pa
)
air purging
air purging
correct value
•Increased Pressure Holes Diameter
•Purging System using Pressurized Air and Electronic Vanes
•Defining of Acquisition Time to 1 sec
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
•Bleeding Air from the Stage Inlet introducing a bent tube facing downstream
•Using Power of the Shaft for the measurement of consumed power
Experimental Set-Up
Compressor Measurements
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
Experimental Set-Up
•Unstable operation can be detected by acoustic measurements
•Use of a Hot-Wire for dry Measurements
•Microphones used for Droplet Laden Flows
Unstable Operation Determination
1.068
1.072
1.076
1.08
1.084
1.088
7 8 9 10 11 12 13
mcor
πC
,cor
6.E-01
7.E-01
8.E-01
9.E-01
1.E+00
7 8 9 10 11 12 13
mcor
RM
S
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
Experimental Analysis of Wet Compression in Axial Experimental Analysis of Wet Compression in Axial Compressor StageCompressor Stage
Experimental Set-Up
Effect of Water Injection on Compressor Stage Aerodynamic Performance
Effect on Compressor Power Consumption
Conclusions
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0.8 0.9 1 1.1 1.2 1.3Φ/Φref
Ψ/Ψ
ref(
t-s,
13)
dry50bar140bar
•Manifold Pressure: 50bar•mwinj/mair=0.6÷0.85%
•MMD=20μm
•Manifold Pressure: 140bar•mwinj/mair=1.1÷1.5%
•MMD=12μm
•Assuming Incompressible Flow
s3 s1s-s,is 2
1 tip
p -pΨ =ρ ×U
Effect of Water Injection on Compressor Stage Effect of Water Injection on Compressor Stage Aerodynamic PerformanceAerodynamic PerformanceEffect on Pressure Rise Coefficient
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0.8 0.9 1 1.1 1.2 1.3Φ/Φref
Ψ/Ψ
ref
(t-s
,13)
drywet
mwinj/mair=1.5%
Accoustic Pressure for wet Operation
0
0.2
0.4
0.6
0.8
1
RM
S/R
MS m
ax
Effect of Water Injection on Compressor Stage Effect of Water Injection on Compressor Stage Aerodynamic PerformanceAerodynamic PerformanceEffect on Pressure Rise Coefficient
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
Effect of Water Injection on Compressor Stage Effect of Water Injection on Compressor Stage Aerodynamic PerformanceAerodynamic Performance
0
0.2
0.4
0.6
0.8
1
0 0.5 1 1.5 2 2.5 3ω/ω,midspan(dry)
Rot
or B
lade
Spa
n
drywetmwinj/mair=2%
•Assuming Incompressible Flow
•Total Pressure Loss Coefficient:
tR1 tR22
1 1
p -pω=1/2×ρ ×W
S
2
tR + Wρ×2
p =p
Total Pressure Loss Coefficient Profile
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
Effect of Water Injection on Compressor Stage Effect of Water Injection on Compressor Stage Aerodynamic PerformanceAerodynamic Performance
•Assuming Incompressible Flow
•Local Total to Total Efficiency:
mwinj/mair=0.6%0
0.2
0.4
0.6
0.8
1
0.6 0.7 0.8 0.9 1 1.1 1.2ηt-t,Local/ηt-t,Local,midspan(dry)
Rot
or B
lade
Spa
n
drywet
( )u2 u1t-t,Local
t2 t1
1 V -Vp -p=
ρ ×Uη
Total to Total Efficiency Profile
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
Effect of Water Injection on Compressor Stage Effect of Water Injection on Compressor Stage Aerodynamic PerformanceAerodynamic Performance
0
0.2
0.4
0.6
0.8
1
0.2 0.4 0.6 0.8 1 1.2a3/a3,midspan(dry)
Stat
or B
lade
Spa
n
drywetmwinj/mair=1.3%
Stator Absolute Exit Angle Profile
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
Water Injection Effect on Compressor Stage OperationWater Injection Effect on Compressor Stage Operation
Experimental Set-Up
Effect of Water Injection on Compressor Stage Aerodynamic Performance
Effect on Compressor Power Consumption
Conclusions
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
0.95
0.96
0.97
0.98
0.99
1
1.01
1.02
0.8 0.9 1 1.1 1.2 1.3 1.4Φ/Φref
Cor
rect
ed c
onsu
med
pow
er
(Pco
mp,
cor/P
com
p,re
f)
mwinj / mair=1%
mwinj / mair=1.3%mwinj / mair=0.5%
mwinj / mair=0.7% dry
Effect on Compressor Power ConsumptionEffect on Compressor Power ConsumptionConsumed Power
•Consumed Power IncreaseDue to the increased mass flow
Due to other reasons
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
ΔPnet/P,dry = 1.044 x mwin/mair0
1
2
0 0.5 1 1.5 2mwin/mair(%)
ΔP n
et/P
,dry
(%)
O.P.1O.P.2O.P.3
ΔPnet/Pdry= 1.0839 x mwin/mair0
1
2
0 0.5 1 1.5 2mwin/mair(%)
ΔP n
et/P
,dry
(%)
50006000700080009000
Effect on Compressor Power ConsumptionEffect on Compressor Power ConsumptionNet Consumed Power Increase
•Consumed Power IncreaseDue to the increased mass flow
Due to other reasons
Operating Point 1
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
•The losses can be attributed to the centrifugation of the droplets by the Rotor
2net TIPΔP =K U winm⋅ ⋅
Compressor stage aerodynamic
efficiency is unchanged
Increase of net consumed power
Effect on Compressor Power ConsumptionEffect on Compressor Power ConsumptionNet Consumed Power Increase
0
0,5
1
1,5
2
0 0,5 1 1,5 2ΔPnet (measured)
45o
P los
ses
calc
ulat
ed (K
=0,3
8)
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
0
0.2
0.4
0.6
0.8
1
0 0.5 1 1.5 2mwin/mair(%)
K
•The losses can be attributed to the centrifugation of the droplets by the Rotor
2net TIPΔP =K U winm⋅ ⋅
Effect on Compressor Power ConsumptionEffect on Compressor Power ConsumptionNet Consumed Power Increase
0
0,5
1
1,5
2
0 0,5 1 1,5 2ΔPnet (measured)
45o
P los
ses
calc
ulat
ed (K
=0,3
8)
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
-2.5
-2
-1.5
-1
-0.5
00 0.5 1 1.5 2
mwin/mair(%)
(ηC
is,w
et-η
Cis, dr
y)/η
Cis, dr
y (%
)
50bar100bar140bar
•Assuming Incompressible Flow
•Isentropic Efficiency via Mechanical Measurements :
1
COMP in
t-t,13C,t-t,is / m
Δp /ρη = P
Efficiency Decrease
Effect on Compressor EfficiencyEffect on Compressor Efficiency
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
•Special Techniques should be used in order to obtain data from a Wet Compressor
•The pressure rise coefficient presented no significant deviation with water injection up to 2%
•Aerodynamic measurements indicate that the stage aerodynamic behavior will not be affected by the presence of droplets for water quantities up to 2%
•Water injection result to an increase of power consumption
•The net increase of the consumed power can be attributed to the centrifugation of the droplets by the rotor
•The increase of power consumption can be described by a single coefficient and the droplet size (from 12μm to 20μm) seems to have no significant effect
ConclusionsConclusions
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
•Further examination of the mechanism resulting to the increase of consumed power at higher rotating speed is needed
•Visual examination of droplet behavior at rotor and stator
•Quantification of the losses in correlation to water collection rate on rotor blades
•Examination of the method of injection on the losses due to water injection (e.g. angle of injection)
Future WorkFuture Work
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LABORATORY OF THERMAL TURBOMACHINESNATIONAL TECHNICAL UNIVERSITY OF ATHENS
Experimental Analysis of Wet Compression in Axial Compressor Stage
•The work for this paper has been carried out in the frame of HERAKLITOS program. The program is co-funded by European Social Fund (75%) and National Resources (25%).
•The cooperation of Mee Industries and Mr T. Mee personally in purchasing the nozzle manifold is gratefully acknowledged
AcknowledgmentsAcknowledgments