Introduction to Hypersonic Propulsion Systems Dr. Andrew Ketsdever Assistant Professor Department of Mechanical and Aerospace Engineering University of Colorado at Colorado Springs aketsdever@eas.uccs.edu http://eas.uccs.edu/aketsdever

Technology Requirements

Propulsion System Factors Efficiency Weight Complexity Variability Longevity and cost of components Fuels (density, rheology, stowability, handling, combustion characteristics, cost) Materials Mission requirements (trajectory, cost, etc.)

Selection Process

Performance Specific impulse Thrust Inert mass fraction All three must be optimized in order to achieve desired outcome

Performance

Materials Temperature Small Space Booster Thrust NASP Chambers Boost Solid Staged Combustion Time, sec Liquid Rocket Engine Nozzles Satellite Propulsion Cruise Missiles Boost Glide Vehicles Thrust Chambers NASP Temperature

Fuels

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!)

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???

Pratt & Whitney J58 Turbo-ramjet cycle 35,000-lb thrust class, 9-stage compressor, SFC 2.17 1/hr

Flight Regimes FLIGHT MACH NUMBER ALTITUDE, KFT 1 2 3 4 5 6 7 200 150 SUBSONIC TURBINE ENGINE HIGH ALTITUDE SUPERSONIC TURBINE ENGINE RAMJET, AIR-AUGMENTED ROCKET LOW ALTITUDE SUPERSONIC TURBINE ENGINE HYPERSONIC RAMJET 150 ALTITUDE, KFT 100 50 1 2 3 4 5 6 7 FLIGHT MACH NUMBER

Propulsion Options Scramjet 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 Body Combustor Isolator Inlet Vehicle and Propulsion system are totally integrated No Moving Parts Necessary Mach 4 and higher Body Fuel Cowl Combustor Forebody (Compression) Nozzle Shock Wave Isolator Inlet

NASA X-34 Scramjet Program "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) 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 Over-Under configuration Accelerator Turbines Turbine-engine inlets Cocooning hot turbine engines will be a technical challenge Tail rockets would likely be added if vehicle is the first stage of launch system

Rocket Based Combined Cycle (RBCC) Rocket-Based Combined Cycle promises a propulsion system that can achieve good performance from M = 0--25 Body Strut & Rockets Cowl Combustor Forebody (Compression) Nozzle Inlet & Door Shock Wave Isolator Vehicle and Propulsion system are totally integrated

RBCC Modes of Operation Air-Augmented Ejector Mode Mach = 0—3 AIR AIR Ramjet Mode M = 3—6 M <1 GREEN ARROWS: FUEL INJECTION AIR M >1 Scramjet Mode M = 6—10 Inlet Closed Rocket Mode M > 10 Each mode is sub-optimized in its operating range

RBCC-TBCC

Pulsed Detonation Engines Pulse Detonation Engine Operating Concept Detonation is initiated 2 Detonation wave moves through fuel-air mixture 3 4 Resulting high pressure gas fills detonation chamber 1 Fuel is mixed with air Detonation wave exits engine Air drawn in by reduced pressure 5 Typical: 40 cycles/sec

Re-Entry

Re-Entry: Meteors Element Color Sodium Iron Magnesium Calcium Silicon