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Aero / Astro
Midterm
23
Mathematics
Undergraduate 1
10/21/2013

Additional Mathematics Flashcards

 


 

Cards

Term
Dynamic Pressure
Definition
  • The kinetic energy of a unit volume of air
  • q
  • q=ro*(v^2)/2 (incompressible)
  • q=gamma*p*(M^2)/2 (compressible)
Term
Incompressible v compressible
Definition

Incompressible- assumes that ro is constant along a streamline

V<40%*a

 

compressible- Assumes that ro changes along a streamline

V>40%*a

Term
Equation of State (Ideal Gas Law)
Definition

P = ro*R*T

R= gas constant

Term
Hydrostatic Equation
Definition
dp = -ro*g*dh
Term
Lapse Rate
Definition
how much the temperature changes as you increase the altitude in a gradient region
Term
Standard atmosphere
Definition

A representative set of atmosphere conditions for computational purposes. Represents pressure, density and temperature at sea level 

p(s) = 101,325 N/m^2 = 2116.2 lb/ft^2

ro(s) = 1.2250 kg/m^3 = 0.002377 slugs/ft^3

T(s) = 288.16 K = 518.69 R

Term
Buoyancy
Definition

The force that points up due to displacement of fluid

F(b) = ro*Volume

Term
4 aerodynamic variables
Definition
Density (ro), pressure (p), velocity (v), temperature (T)
Term
Continuity Equation
Definition

S(1)*v(1)= S(2)*v(2)  (incompressible)

 

ro(1)*S(1)*v(1)= ro(2)*S(2)*v(2) (compressible)

 

basically means air in a streamline can't be destroyed, the toal mass going in and out must be the same at every instance 

v(2) = v(1)*(S(1)/S(2))

Term
Bernoulli's equation
Definition

P(2) + (ro*(v(2)^2)/2) = P(1) + (ro*(v(1)^2)/2)  = B

^^incompressible

 

 

Also know compressible- too long to type. 

(gamma/gamma-1)(P(t)/ro(t))....

Term
Total pressure/Stagnation pressure
Definition

static pressure+dynamic pressure (incompressible)

 

P(0) (1 + ((gamma-1)*(M(0)^2))/2)^

(gamma/(gamma-1)) 

^^(compressible)

Term
pitot tube
Definition

measures total (stagnation) pressure 

 

pitot-static can measure static pressure as well, allowing dynamic pressure and velocity to be calculated

 

p(1) - p(2) = w*dh

Term
adiabatic, reversible and isentropic flow
Definition

adiabatic - a process in which no heat is added or taken away. dQ=0

 

reversible - a process in which no frictional or other dissibpatice effects occur

 

isentropic - a process that is both adiabatic and reversible

Term
speed of sound
Definition

varies with temperature of the air

 

a = sqrt(gamma*R*T)

 

a = velocity/M

Term
Mach number
Definition

Use this to find stagnation conditions

 

Velocity/a

Term
Supersonic properties
Definition

to speed something up subsonically, use a convergent duct

 

to speed something up supersonically, use a divergent duct

Term
four elementary flows
Definition

uniform flow |||||||||

circular flow (O)

             v

sink flow  -> o <-

             ^

                ^

source flow <-o->

                v       

Term
Superposition/Superimposing flows
Definition

we are permitted to superimpose simple flow patterns to create complex flow by the Principle of superposition


-simple flows can be combined together provided that the addition is done vectorically

Term
Computuing circulation
Definition

Γ=Velocity*2*pi*r (for a line)

 

Γ=Velocity*4*pi*r (for a half line)

 

 

♠♦♥♣

Term
kutta joukowski law
Definition

training edge is sharp and therefore, stagnation pt is at trailing edge 

 

Keeps circulation high which leads to more lift 

Term
D'Alambert's paradox
Definition
lift and drag are impossible
Term
Finite wing
Definition
Making the wing finite creates a 3D flow. leaking effects add another dimention to flow. Creates downwash and vortecies tend to merge.
Term
Induced drag
Definition

the downward velocity component of downwash 

 

 

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