Transcript SAB Brief
Dr. Andrew Ketsdever Assistant Professor Department of Mechanical and Aerospace Engineering University of Colorado at Colorado Springs [email protected] http://eas.uccs.edu/aketsdever 2 Efficiency Weight Complexity Variability Longevity and cost of components Fuels (density, rheology, stowability, handling, combustion characteristics, cost) Materials Mission requirements (trajectory, cost, etc.) 3 4 Specific impulse Thrust Inert mass fraction All three must be optimized in order to achieve desired outcome 5 6 Temperature Small Space Booster Boost Glide Vehicles •Solid Staged Combustion Thrust Chambers Cruise Missiles Liquid Rocket Engine Nozzles NASP Satellite Propulsion Booster Time, sec 7 8 Most launch vehicles are rockets, which suffer from low specific impulse compared with airbreathing 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!) 9 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??? 10 35,000-lb thrust class, 9-stage compressor, SFC 2.17 1/hr 11 200 SUBSONIC TURBINE ENGINE HIGH ALTITUDE SUPERSONIC TURBINE ENGINE RAMJET, AIR-AUGMENTED ROCKET ALTITUDE, KFT 150 LOW ALTITUDE SUPERSONIC TURBINE ENGINE HYPERSONIC RAMJET 100 50 0 0 1 2 3 4 5 FLIGHT MACH NUMBER 6 7 12 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) 13 Vehicle and Propulsion system are totally integrated No Moving Parts Necessary Mach 4 and higher Body Fuel Cowl Combustor Forebody (Compression) Nozzle Inlet Isolator 14 "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." 15 •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 16 Rocket-Based Combined Cycle promises a propulsion system that can achieve good performance from M = 0--25 Body Strut & Rockets Cowl Combust or Forebody (Compression) Inlet & Door Nozzle Isolator Vehicle and Propulsion system are totally integrated 17 Air-Augmented Ejector Mode Mach = 0—3 AIR AIR M <1 Ramjet Mode M = 3—6 GREEN ARROWS: FUEL INJECTION AIR M >1 Inlet Closed Scramjet Mode M = 6—10 Rocket Mode M > 10 Each mode is sub-optimized in its operating range 18 19 Pulse Detonation Engine 2 1 Operating Concept Detonation is initiated 3 Detonation wave moves through fuel-air mixture 4 Fuel is mixed with air 5 Detonation wave exits engine Air drawn in by reduced pressure Resulting high pressure gas fills detonation chamber Typical: 40 cycles/sec 20 21 Element Color Sodium Iron Magnesium Calcium Silicon 22 23