dr. andrew ketsdever assistant professor department of mechanical and aerospace engineering...
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Introduction to Hypersonic Propulsion
SystemsDr. Andrew Ketsdever
Assistant ProfessorDepartment of Mechanical and Aerospace Engineering
University of Colorado at Colorado [email protected]
http://eas.uccs.edu/aketsdever
Technology Requirements
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Propulsion System FactorsEfficiency Weight Complexity Variability Longevity and cost of components Fuels (density, rheology, stowability,
handling, combustion characteristics, cost)
Materials Mission requirements (trajectory,
cost, etc.)
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Selection Process
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Performance
Specific impulse Thrust Inert mass fraction All three must be optimized in order
to achieve desired outcome
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Performance
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Materials
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SmallSpace
Booster
• SolidStaged
Combustion
Time, sec
LiquidRocketEngineNozzles
SatellitePropulsion
Booster
CruiseMissiles
BoostGlide
Vehicles
ThrustChambers
NASP
Temperature
Fuels
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Problems
Most launch vehicles are rockets, which suffer from low specific impulse compared with air-breathing systems (5000 sec. for turbojets vs. 500 sec. for rockets)
This degrades overall performance and increases weight (a good reason to investigate hybrid systems for future launch vehicles!)
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Problems
The need to carry so much fuel makes overall weight a crucial design factor
The structure of the vehicle is made as light as possible to compensate
Boosters are not strong, rigid bodies. While they are fairly strong longitudinally, they are very weak laterally
Most rockets cannot fly at significant angles of attack through the atmosphere or they would fall apart!
A rocket carrying satellites usually starts vertically, but must end in a horizontal orbit trajectory How can you control trajectories??? How do you keep from falling apart???
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Pratt & Whitney J58 Turbo-ramjet cycle
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35,000-lb thrust class, 9-stage compressor, SFC 2.17 1/hr
Flight Regimes
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200
150
100
50
0
SUBSONIC TURBINE ENGINE
HIGH ALTITUDE SUPERSONIC TURBINE ENGINERAMJET, AIR-AUGMENTED ROCKET
LOW ALTITUDE SUPERSONIC TURBINE ENGINE
HYPERSONIC RAMJET
ALT
ITU
DE
, KF
T
1 2 3 4 5 6 70
FLIGHT MACH NUMBER
Propulsion Options
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Combined cycle Propulsion “Low speed” cycle + scramjet
Rocket Based Combined Cycle (RBCC):Mach 0--25 air-breathing +rocket + scramjet + rocket
Turbine Based Combined Cycle (TBCC):Mach 0--4, 5 turbine + scramjet
• Scramjet– Supersonic combustion ramjet– Hydrocarbon (Mach 3-8)– Hydrogen (Mach 3-15)
Scramjet
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Forebody
(Compression) Shock Wave
Inlet
Body
Cowl
Combustor
Nozzle
Isolator
Mach 4 and higher
Fuel
No Moving Parts Necessary
Vehicle and Propulsion system are totally integrated
NASA X-34 Scramjet Program
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"On 16 November, 2004, NASA's unmanned Hyper-X (X-43A) aircraft reached Mach 9.6 (~7,000mph). The X-43A was boosted to an altitude of 33,223 meters (109,000 feet) by a Pegasus rocket launched from beneath a B52-B jet aircraft. The revolutionary 'scramjet' aircraft then burned its engine for around 10 seconds during its flight over the Pacific Ocean."
Turbine Based Combined Cycle (TBCC)
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• Accelerator Turbine (Mach 0—4.3) is combined with a duel-mode scramjet engine (Mach 4—8)
• Transition from turbine power to ramjet is performed at Mach 4
• Cocooning hot turbine engines will be a technical challenge
• Tail rockets would likely be added if vehicle is the first stage of launch system
Turbine-engine inlets
Accelerator Turbines
Over-Under configuration
Rocket Based Combined Cycle (RBCC)
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Forebody
(Compression)Shock WaveInlet
&Door
Body
CowlCombust
orNozzle
Isolator
Strut & Rockets
Vehicle and Propulsion system are totally integrated
Rocket-Based Combined Cycle promises a propulsion system that can achieve good performance from M = 0--25
RBCC Modes of Operation
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AIR
AIR
AIR
Inlet Closed
GREEN ARROWS: FUEL INJECTION
Air-AugmentedEjector ModeMach = 0—3
Ramjet Mode M = 3—6
Scramjet Mode M = 6—10
Rocket Mode M > 10
M >1
M <1
Each mode is sub-optimized in its operating range
RBCC-TBCC
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Pulsed Detonation Engines
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Pulse Detonation Engine Operating Concept
Detonation is initiated2 Detonation wave movesthrough fuel-air mixture
3
Detonation wave exits engineAir drawn in by reduced pressure
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1 Fuel is mixed with air 4 Resulting high pressure gasfills detonation chamber
Typical:
40 cycles/sec
Re-Entry
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Re-Entry: Meteors
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Element ColorSodiumIronMagnesiumCalciumSilicon
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