AAE 3710
Fundamentals of Aerodynamics
Lecture 1 Introduction
01/11/2006
What is fluid
• Some common fluid pictures
Aurora: seen in high latitude region
Origin: solar wind, i.e. plasma captured by
magnetic field of Earth and move
parallel to the magnetic field lines.
Mechanism: the plasma stream enters the
atmosphere and collide with particles
floating in it. Very high energy released
from collision will generate some visible
light.
What is fluid
Flow visualization
by condensation.
Mechanism: from
thermodynamics,
significant
pressure drop
causes water
vapor to
condense.
Condensation caused by
large lift maneuvers.
What is fluid
Shock wave generated in a wind tunnel
Shock wave is usually
found in high-speed
flows. Fluid
properties undergo
dramatic,
discontinuous
changes when pass a
shock wave.
Very important in
aerodynamics.
Firing of 16inch and
5inch guns of USS
Iowa
What is fluid
• Pressure contour
of the SSC, the
supersonic car,
tested on the
Black Rock
Desert in
Nevada
What is fluid
Picture of oblique shock taken on the supersonic car
What is fluid
• Large
scale
vorticestornado.
What is fluid
• Wing tip
vortices on
F-16 in a
high-g
maneuver
What is fluid
• Two meta
stable states of
microfluidic
memory chip
• By using sharp
momentary
increase in the
flow, the flow
direction of
dark fluid can
be switched
representing
binary state.
What is fluid
• From dictionary, A substance (as a liquid
or gas) tending to flow or conform to the
outline of its container.
• From the text, A fluid is defined as a
substance that deforms continuously when
acted on by a shearing stress of any
magnitude. Why? Weak intermolecular
force.
Unit system
Basic quantities
BG(British
Gravitational)sys
SI(International
System)
Conversion factors
*Mass (M)
slug
kg (kilogram)
1 kg = 0.068522 slug
*Length (L)
ft (foot)
m (meter)
1 m = 3.28084 ft
*Time (T)
s (second)
s (second)
Force
lb (pound)
N (Newton)
1 N = 0.224809 lb
F (Fahrenheit)
R = F + 459.67
C (celcius)
K = C + 273.15
1 c = 33.8 F
K (kelvin)
1 K = 1.8 R
*TemperatureΘ
Absolute Temperature F R (Rankine)
o
Standard gravity g=32.174 ft/s^2[BG]; g=9.807 m/s^2[SI]
W = mg
Unit System
Five primary quantities (FLT or MLT):
Length, Time, Mass, and Temperature;
Other secondary quantities can be derived
from primary quantities;
e.g.
Area=?
Velocity=?
Density=?
http://www.digitaldutch.com/unitconverter/
Unit System
• All physically correct equations have to be
dimensionally homogeneous
e.g. F=ma
FLT
L.H.S. [F]=F;
R.H.S.[m][a]=FTT/L*L/(TT)=F
[L.H.S.]=[R.H.S.]
MLT
L.H.S. [F]=ML/(TT);
R.H.S.[m][a]=ML/(TT)
[L.H.S.]=[R.H.S.]
Measures of Fluid Mass and
Weight
•
•
•
•
Density
Specific Weight
Specific Gravity
Ideal Gas Law
Measures of Fluid Mass and Weight
Measures of Fluid Mass and Weight
• Viscosity
Real fluid tends to
stick to the surface it
passes by.
Measures of Fluid Mass and Weight
• Most common
liquids and
gases are
Newtonian
fluids, e.g. they
follow the
relation
Measures of Fluid Mass and Weight
Compressibility of Fluids
• Speed of sound, an important
consequence of the compressibility of
fluids
For ideal gas, the speed of sound is
proportional to the square root of the
absolute temperature.