Marc Williams School of Aeronautics and Astronautics Aeronautics Airplanes Astronautics Spacecraft Parts of Aero amp Astro Aerodynamics Design Dynamics amp Control Structures Propulsion ID: 702882
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Slide1
Fluid Mechanics in Aeronautics and Astronautics
Marc WilliamsSchool of Aeronautics and AstronauticsSlide2
Aeronautics = AirplanesSlide3
Astronautics = SpacecraftSlide4
Parts of Aero & Astro
Aerodynamics
Design
Dynamics & Control
Structures
PropulsionSlide5Slide6
Three forces from fluidsLIFT - 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 directionInternal pressure inside the engine pushes the aircraft/rocket forwardSlide7
LIFT
Newton say : The air pushes the airplane up So
The airplane pushes the air downSlide8
Cessna Citation Slide9
Boeing 777Slide10
Boeing 757Slide11
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)
Slide12
Flight Regimes – A Vocabulary
0
0 1.0 2.0 3.0 6.0
Mach Number – M
Altitude
(1000 ft.)
100
80
60
40
20
Subsonic
Supersonic
Hypersonic
Structural Limit
(Dynamic pressure and heating)
Aerodynamic
Limit
Transonic
V = flight speed
a = speed of sound
M = V / aSlide13
Wing Loading (N/m
2
)
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
Conventional Aircraft
(Steady)
Large Birds
(Quasi-steady)
Small Birds (Transition)
Insects/Hummingbirds
(Unsteady)
Cruising Speed (m/s)
Weight (N)Slide14
Micro Air Vehicles (MAVs)
Unmanned aerial systems becoming for missions too dull, dirty, dangerous, or difficult for pilotsPersistent ISRChemical/biological sensing
“Over the hill”/“Around the corner” scoutingOperation space is changingUrban canyonsBuilding interiors
Subterranean caverns/bunkers
MAVs are new class of vehicle to fill new operational roles
Images from wikipedia.org, defense-update.com, delta.tudelft.nlSlide15
DYNAMICS AND CONTROL
http://www.grc.nasa.gov/WWW/K-12/airplane/alr.htmlSlide16
Mach Number Effects
Mach Number = Speed / Speed of Sound Speed of Sound = 340 m/s = 770 mph
Mach squared = Kinetic Energy / Thermal EnergySlide17
An
F/A-18 Hornet at
transonic speed Slide18
F4 phantom ii breaking the sound barrier Slide19Slide20
Mars Exploration Rover
(MER)
aeroshell, artistic renditionSlide21
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 withSlide22
Air ThrowerSlide23
http://www.youtube.com/watch?v=nSQzvimD3cc
Turbofan Engine
This throws air and hot exhaust gasesSlide24
Turbofan FlowpathSlide25
Tomahawk Cruise MissileSlide26
Mi-24 Hind Military Aviation Helicopter
Air ThrowerSlide27
Joint Strike Fighter- Marine Version
Lift Fan
Another Air ThrowerSlide28
OSPREY- Tilt Rotor
And another… but you get to change the throw direction Slide29
Rockets – Pure Hot Gas ThrowersSlide30
How a Rocket Produces ThrustSlide31
ROCKETS
BIG (SSME)Slide32
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.
ROCKETS: SMALLSlide33
Sidewinder
Air to Air supersonic missileSlide34Slide35
THE ENDHave a great summerSlide36Slide37
Dynamic Stall on an AirfoilSlide38
Boeing 757Slide39
Vortex break-up on a delta wing at high incidence Slide40