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Fluid Mechanics in Aeronautics and Astronautics

Fluid Mechanics in Aeronautics and Astronautics. Marc Williams School of Aeronautics and Astronautics. Aeronautics = Airplanes. Astronautics = Spacecraft. Parts of Aero & Astro. Aerodynamics. Design . Structures. Dynamics & Control. Propulsion. Three forces from fluids.

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Fluid Mechanics in Aeronautics and Astronautics

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  1. Fluid Mechanics in Aeronautics and Astronautics Marc Williams School of Aeronautics and Astronautics

  2. Aeronautics = Airplanes

  3. Astronautics = Spacecraft

  4. Parts of Aero & Astro Aerodynamics Design Structures Dynamics & Control Propulsion

  5. Three forces from fluids • LIFT - Force perpendicular to flight direction The Air pushes the airplane “up” • DRAG - Force opposite the flight direction The Air pushes the airplane “back” • THRUST - Force in the flight direction Internal pressure inside the engine pushes the aircraft/rocket forward

  6. LIFT Newton say : The air pushes the airplane up So The airplane pushes the air down

  7. Cessna Citation

  8. Boeing 777

  9. Boeing 757

  10. DRAG • The air sticks to the airplane, pushing it back • (Viscosity== Friction drag) • The airplane imparts kinetic energy to the air • behind it…. This energy comes from the engines, • And shows up as a drag • (Induced Drag, or Drag due to Lift)

  11. Flight Regimes – A Vocabulary SubsonicSupersonicHypersonic 100 80 60 40 20 Transonic Altitude (1000 ft.) Structural Limit (Dynamic pressure and heating) Aerodynamic Limit V = flight speed a = speed of sound M = V / a 0 0 1.0 2.0 3.0 6.0 Mach Number – M

  12. All the Worlds Flyers • Flyers meeting MAV requirements abound in nature • Flyers with most remarkable performance leverage unsteady aerodynamics • Flapping provides access to game-changing aerodynamic mechanisms for meeting MAV requirements Wing Loading (N/m2) Conventional Aircraft (Steady) Large Birds (Quasi-steady) Weight (N) Small Birds (Transition) Insects/Hummingbirds (Unsteady) Cruising Speed (m/s)

  13. Micro Air Vehicles (MAVs) • Unmanned aerial systems becoming for missions too dull, dirty, dangerous, or difficult for pilots • Persistent ISR • Chemical/biological sensing • “Over the hill”/“Around the corner” scouting • Operation space is changing • Urban canyons • Building interiors • Subterranean caverns/bunkers • MAVs are new class of vehicle to fill new operational roles Images from wikipedia.org, defense-update.com, delta.tudelft.nl

  14. DYNAMICS AND CONTROL http://www.grc.nasa.gov/WWW/K-12/airplane/alr.html

  15. Mach Number Effects • Mach Number = Speed / Speed of Sound • Speed of Sound = 340 m/s = 770 mph • Mach squared = Kinetic Energy / Thermal Energy

  16. An F/A-18 Hornet at transonic speed

  17. F4 phantom ii breaking the sound barrier

  18. Mars Exploration Rover (MER) aeroshell, artistic rendition

  19. Thrust • Thrust is produced by throwing something opposite to the • direction you want to go (Newton again) • You can throw air • You can throw hot exhaust gases • You can throw rocks… but fluids are easier to work with

  20. Air Thrower

  21. http://www.youtube.com/watch?v=nSQzvimD3cc Turbofan Engine This throws air and hot exhaust gases

  22. Turbofan Flowpath

  23. Tomahawk Cruise Missile

  24. Air Thrower Mi-24 Hind Military Aviation Helicopter

  25. Joint Strike Fighter- Marine Version Lift Fan Another Air Thrower

  26. OSPREY- Tilt Rotor And another… but you get to change the throw direction

  27. Rockets – Pure Hot Gas Throwers

  28. How a Rocket Produces Thrust

  29. ROCKETS BIG (SSME)

  30. ROCKETS: SMALL A micro-thruster array measuring one-quarter the size of a penny, designed by a TRW-led team for use on micro-, nano- and pico-satellites, has successfully demonstrated its functionality in a live fire test aboard a Scorpius sub-orbital sounding rocket. Individual micro-electromechanical system (MEMS) thrusters, each a poppy seed-sized cell fueled with lead styphnate propellant, fired more than 20 times at 1-second Intervals during the test staged at the White Sands Missile Range. Each thruster delivered 10(-4) Newton seconds of impulse.

  31. Sidewinder Air to Air supersonic missile

  32. THE END Have a great summer

  33. Dynamic Stall on an Airfoil

  34. Boeing 757

  35. Vortex break-up on a delta wing at high incidence

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