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ROCKET AND AIRPLANE PROPULSION

ROCKET AND AIRPLANE PROPULSION. Dr. Daniel Kirk Associate Professor and Associate Department Head MAE Mechanical and Aerospace Engineering Department Florida Institute of Technology dkirk@fit.edu March 26, 2012. CONTENTS. Basic overview of propulsion

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ROCKET AND AIRPLANE PROPULSION

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  1. ROCKET AND AIRPLANE PROPULSION Dr. Daniel Kirk Associate Professor and Associate Department Head MAE Mechanical and Aerospace Engineering Department Florida Institute of Technology dkirk@fit.edu March 26, 2012

  2. CONTENTS • Basic overview of propulsion • Rocket vs. airplane engines: advantages and disadvantages • How to analyze with Newton’s second law • Rocket propulsion • Why do we use rockets? • Liquid and solid propellant types • Research examples • Air-breathing propulsion • Why do we use air-breathing propulsion systems • Civilian vs. Military engine example

  3. BASIC OVERVIEW OF PROPULSION

  4. Take mass stored in a vehicle and throw it backwards → Use reaction force to propel vehicle All fuel and oxidizer are carried onboard the vehicle Capture mass from environment and set that mass in motion backwards → Use reaction force to propel vehicle Only fuel is carried onboard Oxidizer (air) is ‘harvested’ continuously during flight ROCKET VS. AIR-BREATHING PROPULSION

  5. ROCKET PROPULSION

  6. OVERVIEW: ROCKET COMPONENTS http://www.boeing.com/defense-space/space/delta/delta4/d4h_demo/book04.html

  7. TYPES OF ROCKETS Bell X-1: XLR11

  8. UNIQUE ROCKET APPLICATIONS

  9. WHY ROCKET PROPULSION? • Rockets provide means to: • Insert satellites into space • Space exploration (Atmospheric, solar system) • Precise, continuous or pulsed, momentum change • Weapons • Rapid change in momentum devices, such as car air-bags • Primary distinction is between chemical and electrical propulsion systems • These are only types of rockets in operation today

  10. CHEMICAL: LIQUID AND SOLID SYSTEMS Liquid Propellants Fuel: LH2 Oxidizer: LOX Solid Rocket Boosters

  11. EXAMPLE: STS EXTERNAL TANK • External tank contains liquid hydrogen fuel and liquid oxygen oxidizer • ~1,000,000 pounds of LO2 • ~200,000 lb LH2

  12. SOLID ROCKET GRAIN GEOMETRY Minuteman first stage motor

  13. EXAMPLE: ELECTRIC AND ION THRUSTERS • Satellite orbit raising and station-keeping applications. • Thrust created accelerating positive ions through gridded electrodes, more than 3,000 tiny beams of thrust. • Ions ejected travel in an invisible stream at a speed of 30 kilometers per second (62,900 miles per hour), nearly 10 times that of its chemical counterpart. • Ion thrusters operate at lower force levels, attitude disturbances during thruster operation are reduced, further simplifying the stationkeeping task. For more on Electric Propulsion: http://hpcc.engin.umich.edu/CFD/research/NGPD/ElectricPropulsion/ http://www.marsacademy.com/propul/propul7.htm http://richard.hofer.com/electric_propulsion.html http://www.stanford.edu/group/pdl/EP/EP.html Designer: Rocketdyne. Developed in: 1999. Propellants: Electric/Xenon Thrust (vac): 0.0001 kgf. Isp: 3,500 s

  14. ENERGY LIMITED VS. POWER LIMITED Electrical Rockets are Power Limited Chemical Rockets are Energy Limited • Chemical rockets have lots of power, but not a lot of energy • Electrical rockets have lots of energy, but not a lot of power

  15. MISSION REQUIREMENT Non-Space Missions Atmospheric / Ionospheric Sounding Tactical Missiles Medium-Long Range Missiles Launch to Space Impulsive DV in Space Time critical maneuvers Energy change from elliptic orbits, plane change from elliptic orbits Non-fuel limited situations Low Thrust DV in Space Mass-limited missions Non-time critical missions Small, continuous orbit corrections, near circular orbits ROCKET TYPE Solid Propellant, 1-4 stages Solid Propellant, 1-2 stages Solid or Liquid Propellant, 2-3 stages (very high acceleration) Solid, liquid or combination, 2-4 stages (2-4g), Possible: hybrid, 2-4 stages Small solid propellant (apogee kick, etc.) Bi-propellant (storable), liquids, monopropellant (storable) liquids. Future: nuclear thermal Solar-electric systems: Arcjet (a bit faster, less Isp), Hall, Ion (slower, higher Isp), PPT (precision maneuvers), Nuclear-electric systems, direct solar-thermal ROCKET SELECTION GUIDE

  16. ROCKET PROPULSION RESEARCH AT FLORIDA TECH

  17. DEPARTMENT OF REDUNDANCY DEPARTMENT Why so many engines? Why not just use 1 big engine?

  18. ROCKET SCALING EXAMPLE • Thrust scales with throat area, A* • Recall Thrust = (mass flow) x (exit velocity) • Mass flow depends on A* • A* scales with L2 • Weight scales with volume, V • V scales with L3 • T/W, therefore scales with 1/L • So what? • Take ‘baseline’ engine and makes 4, ½-size copies of it • 1/4th A* of original • 1/8th Volume of original • 4 engines together produce same thrust as baseline, but only weight half as much! • Do same with half size engine, and make 16 quarter-sized engines • Together produce same thrust as original, but weigh a quarter of original • In theory, process could be continued indefinitely • Massively-parallel thrust system with a very high thrust to weight ratio

  19. mROCKET PROJECT • Design complete rocket system, tanks, valves, turbomachinery, thrust chamber • Mass production, silicon-carbide material • Launch and orbital applications, T~ 5-15 N, Isp ~ 300 sec • Higher T/W than Space Shuttle

  20. mROCKETS • Six Wafers • Eight Masks • Smallest feature ~ 10 mm 10 cm

  21. NUCLEAR THERMAL ROCKET PROPULSION • NTP improvement: 100-400% improvement over best conventional rocket motors • Highly reduced mission times (1 year vs. 3 years to Mars) • Safety is major consideration and challenging to design

  22. NTREES: NUCLEAR THERMAL ROCKET ENVIRONMENTAL ELEMENT SIMULATOR AT NASA MSFC • Non-nuclear testing is key to engine development • Design of experiment for NASA MSFC • Heat exchanger designed by Florida Tech students Grooved Ring Fuel Element

  23. What can happen to rockets in space? Need an environment to study and perform experiments without gravity Aircraft testing is a popular approach

  24. Reduced Gravity Slosh Dynamics Study F A S T Illuminated by

  25. AIR-BREATHING PROPULSION

  26. AIR-BREATHING PROPULSION • Gas turbine engines power every modern aircraft and will for foreseeable future • Gas turbines used for land-based power application, rocket engine turbo-pumps, marine applications, ground vehicles (tanks), etc. • Many technical challenges remain to be addressed (Fuel Economy and Noise) • Fluid mechanics, thermodynamics, combustion, controls, materials, etc. • One of most complicated, parts, extreme environment device on earth • Enormous market: vast research and development $$ • Market is so competitive that engines are sold for a loss

  27. VARIOUS NUMBER OF ENGINE CONFIGURATIONS 2 Engines 3 Engines 4 Engines 6 Engines

  28. COMMERCIAL AIRCRAFT: BOEING SERIES 707 757 727 767 737 777 747 787

  29. BOEING 747-110 (1973) vs. 747-800 (2009)

  30. CROSS-SECTIONAL EXAMPLE: GE 90-115B Compressor Nozzle Fan Turbine Combustor Inlet • Why does this engine look the way that it does? • How does this engine push an airplane forward, i.e. how does it generate thrust? • What are major components and design parameters? • How can we characterize performance and compare with other engines?

  31. TRENDS TO BIGGER ENGINES 1995: Boeing 777, FAA Certified 1958: Boeing 707, United States' first commercial jet airliner Similar to PWJT4A: T=17,000 lbf, a ~ 1 PW4000-112: T=100,000 lbf , a ~ 6

  32. HOW LARGE IS 777-300 ENGINE? 11 ft 7 in (3.53 m) 11 ft 3 in (3.43 m) Engine is largest and most powerful turbofan built (11 ft 3 in (3.43 m) in diameter) In this case, 737 cabin is a mere 3% wider than 777 engine

  33. COMMERCIAL AND MILITARY ENGINES(APPROX. SAME THRUST, APPROX. CORRECT RELATIVE SIZES) GE CFM56 for Boeing 737 T~30,000 lbf, a ~ 5 P&W 119 for F- 22, T~35,000 lbf, a ~ 0.3

  34. CHEMICAL EMISSIONS

  35. AIRCRAFT AND ENGINE NOISE

  36. AIRCRAFT NOISE

  37. ENGINE TESTING: BIRD STRIKE http://100.rolls-royce.com/facts/view.jsp?id=215 http://www.aviationexplorer.com/a6_engine_ingestion.htm

  38. HOW SERIOUS CAN A BIRD STRIKE BE?

  39. MACH 0.8 vs. MACH 8.0

  40. SCRAMJET PROPULSION: X-43 MACH 10!

  41. X-43A DETAILS

  42. X-51: HYPERSONIC FLIGHT

  43. Summary • Propulsion is an exact, but not a fundamental subject • No basic scientific laws of nature peculiar to propulsion • Incorporates fluid mechanics, thermodynamics, combustion, structures, materials, etc. • Many exciting future opportunities: Rockets • Very large rockets for Moon and Mars missions • Very small rockets for pulse/orbital correction applications • Many exciting future opportunities: Air-Breathing Engines • Will propel airplanes for foreseeable future • Improved fuel economy • Reduced noise and chemical emissions • Exciting / challenging area in aerospace engineering

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