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Definition
(1+ [(γ-1)/2]M1^2)^[γ/(γ-1)]
For Isentropic Flow
γ = Gamma |
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Term
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Definition
(1+ [(γ-1)/2]M1^2)^[γ/(γ-1)]
For Isentropic Flow |
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Term
| Density1*Area1*Velocity1 = |
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Definition
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Term
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Definition
Isentropic flow is flow that is Adiabatic and reversible, meaning that:
1) No heat is added or taken away
2) No friction or other dissipative effects occur. |
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Term
For Isentropic Flow:
P2/P1 = ? = ?? |
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Definition
| = (Roh2/Roh1)^γ = (T2/T1)^(γ/(γ-1)) |
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Term
| Air can be assumed to be Incompressible if |
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Definition
V < 100 M/s
or
V < 225 Miles/Hour
or
If Mach # < 0.3 |
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Term
| Define Eulers Equation, and explain how it is used. |
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Definition
dP = -Roh*V*dV
It relates the change of momentum to the force, It is also referred to as the Momentum Equation |
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Term
| Define Bernoulli's Equation, and explain how it is used |
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Definition
P1+Roh*[(V1^2)/2] = P2+Roh*[(V2^2)/2]
Or
P+Roh*[(V^2)/2] =Constant along Streamline
Only Holds true for Inviscid(frictionless), Incompressible flow. Must NOT be used for comressible Flow |
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| Define the Equation of State |
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Definition
P1 = Roh1*(R)*(T1)
R = Constant = 287 for SI, or 1716 for US.
T = Temperature = Kelvin or Rankine
0F = 460 Rankine
0C = 273K = 32F |
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| Define the first law of Thermodynamics |
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Definition
δQ + δw = de
The sum of the heat added + the sum of the work done on the system = the change in internal energy. |
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Term
Define the terms of this equation
h1 + (V1^2)/2 = h2 + (V2^2)/2
or
h + (V^2)/2 = Constant |
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Definition
h = CpT where Cp [u]=[/u] (δQ/dT) Constant Volume, T = Temperature
V = velocity
Also can be written as
CpT1 + (V1^2)/2 = CpT2 + (V2^2)/2 |
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Term
Finish these Equations, and name them:
a) Roh1*A1*V1 =
b) P1 + (1/2)*Roh*(V1^2) =
c) CpT1 + (V1^2)/2 =
d) P1 = |
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Definition
a) Roh2*A2*V2 (Continuity)
b) P2 + (1/2)*Roh*(V2^2) (Bernoulli)
c) CpT2 + (V2^2)/2 (Energy) (Cp =[u]=[/u] (δQ/dT) Constant Volume, T = Temperature)
d)Roh1*R*T1 (Equation of state, R = 287 or 1716) |
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Term
| The speed of sound in a perfect gas depends only on ... |
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Definition
...The temperature of the gas.
a = Sqrt(γRT) = Speed of sound
γ = 1.4 for Air on earth |
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Term
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Definition
V/a, where V is the speed of the object (in ft/s)
and a is the speed of sound
(in ft/s)
a must be determined by the equation:
a = Sqrt(γRT) = Speed of sound
γ = 1.4 for Air on earth
if Altitude is given, use altitude table to determine T
If M<1, flow is subsonic
if M=1, flow is sonic
If M > 1, flow is supersonic
if M >> 1, flow is hypersonic ( M > 5)
If 0.8 [u]<[/u] M [u]<[/m] 1.2, flow is transonic |
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Term
| Convert 550 Mi/h to ft/s: |
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Definition
88 ft/s = 60 mi/h ...
Therefore 550 (Mi/h)*(88/60) = 807 ft/s |
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Term
For a manometer used to measure pressure differences in a wind tunnel:
P1*A =
or
P1-P2 = |
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Definition
= P2*A + ω*A*Δh
or
= ω*A*Δh
ω*A*Δh = [Roh(fluid)*g(gravity)]*(Area)*(difference of heights between two tubes) |
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Term
| When dealing with low speed subsonic flow: |
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Definition
V2 = Sqrt[(2*(P1-P2))/(Roh*(1-(A2/A1)^2))]
since we asume Roh1 = Roh for low speed subsonic flow. |
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Term
When calculating Mass flow:
M = |
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Definition
Roh1*A1*V1
or
Roh*A1*V1 for low speed subsonic airflow
also
= Roh*A2*V2.
Can be measured anywhere in the airflow
M = roh*A*V |
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Term
| Compare static and total pressure |
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Definition
Static pressure is the pressure felt by a particle of air in the airflow, while Total presure is the presure felt by a foreign object in the airflow.
For ex, A bug flies into you inside your car while you are driving, windows up, at 60mph. since both you and the bug are doing 60mph, the force is very small.
now if you open the window, and the bug flies out and hits a person standing on the side of the road, the force is much greater, since the bug and person are not traveling the same speed. |
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Term
Define Vtrue and Ve
Vtrue =
Ve = |
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Definition
Sqrt[(2*(P0-P))/Roh] for Vtrue
Sqrt[(2*(P0-P))/Roh(s)] for Ve, where Roh(s) is the air density at sea level |
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Term
A pitot tube is used to measure air pressure acting on an aircraft. The equation for this is
P0/P1 =
P0 = total pressue, |
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Definition
(1 + [(γ-1)/2]*M1^2)^[γ/(γ-1)]
γ = 1.4 |
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Term
The relationship between T0 (total temperature) and T1 (static temperature) is given by
T0/T1 = |
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Definition
1+ [(γ-1)/2]*M1^2
γ = 1.4 |
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Term
The relationship between Roh0 and Roh1 is shown by the equation :
Roh0/Roh1 =
Roh0 = Total density
Roh1 = static Density |
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Definition
= (1 + [(γ-1)/2]*M1^2)^[1/(γ-1)]
γ = 1.4 |
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Term
As a fluid element flows through a shock wave
a) Mach number (M)
b) static pressure (P1)
c) static Temperature (T1)
d) flow velocity
e) Total Pressure (P0)
f) Total temperature (T0) |
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Definition
a) decreases
b) increases
c) increases
d) decreases
e) decreases
f) stays the same (for a perfect gas) |
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Term
For Pitot Tubes in supersonic airspeeds, the shockwave must be accounted for
P(02)/P1 = |
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Definition
{[((γ+1)^2)*M1^2]/[4*γ*M1^2-2(γ-1)]}^[γ/(γ-1)]
All that ^^ Times (*) [1-γ+2γ*M1^2]/(γ+1)
Rayleigh Pitot Tube formula, where P(02) is the total P behind the wave, and P1 is the tatic pressure infront of the wave. |
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Term
a) For subsonic airflow, for the velocity to inrease, the Area must ...
b) for Supersonic airflow, for the velocity to increase, the area must |
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Definition
a) decrease ( think subsonic wind tunnel)
b) Increase (think rocket engine nozzle) |
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Term
| The boundary layer that surrounds an object in an airstream is caused by |
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Definition
| friction between the gas and the surface of the object |
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Term
| The shear stress due to air resistance is |
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Definition
τw = μ*(dV/dY), Y = 0
μ = absolute viscosity coefficient of the gas (mass/(length*time)) |
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