Equations - Meaning and Units Flashcards
What is the equation/ units for mass flow rate?
ρvA=C
Units: kg/s
What is the equation/ units for volume flow rate?
v*A=C
Units: m^3/s
What is the units for the outcome of Bernoulli’s equation?
Total pressure - Pascals
What is each component of Bernoulli’s equation called? what does each mean?
ghρ = Potential pressure (due to change in height) p = static pressure 0.5*ρ*v^2 = Dynamic Pressure (due to particles being bright to rest in airflow) P = Total Pressure
What is each component of Bernoulli’s equation for total head?
h = (natural) head v^2/(2g) = Dynamic head p/(gρ) = Static head H = Total head
What are the conditions to use Bernoulli’s equation?
Incompressibility
Ideal fluid
Steady state
Follow streamlines
What is the Equation for calculating total pressure when you have static and dynamic pressure?
Static pressure + Dynamic pressure
What is the state equation of gas? Derived from the ideal gas law?
p1/(ρ1T1) = p2/(ρ2T2)
(p1V1)/T1 = (p2V2)/T2
What is the first law of thermodynamics? (energy conservation). What does each symbol represent?
Q = E + W
Q = Heat transferred to/from the system E = Change in internal energy of the gas W = Work done to/by the system
What equations (2) can be derived from the ideal gas law if it undergoes an isothermal state change?
p1V1 = p2V2
p1/ρ1 = p2/ρ2
What equations can be derived from the ideal gas law if a gas undergoes an isobaric state change?
V1/T1 = V2/T2
ρ1T1 = ρ2T2
What equations can be derived from the ideal gas law is a gas undergoes an isochoric/ isovolumetric state change?
p1/T1 = P2/T2
p1/P2 = T1/T2
What equations (3) can be derived from the ideal gas law/ first law of thermodynamics if a gas undergoes an adiabatic state change?
P1V1^γ = P2V2^γ
P1/ρ1^γ = P2/ρ2^γ
(P1^(γ-1))/T1^γ = (P2^(γ-1))/T2^γ
What does each component of the shear stress equation mean? Units?
µ = Dynamic viscosity: Pa*s ∂u/∂y = Speed gradient in the y direction τ = Shear stress
What is the equation for Kinematic viscosity?
µ/ρ
What is the equation for Reynolds Number? Units? What is its meaning? What is the meaning of l?
Re= ρvl/ µ
Dimensionless number used to classify the status of fluid flow
In a pipe it is the diameter (m), over a plate, it is the characteristic length (m)
In a pipe, when is flow, turbulent, laminar or transition?
Laminar if Re<2000
Transition if 2000 4000
Over a flat plate, when is a boundary layer flow laminar or turbulent?
Laminar if Re < 510^5
Transition if Re > 510^5 or Re < 510^6
Turbulent if Re > 510^6
Describe the NACA naming convention?
1st number: percentage of max camber to chord
2nd number: position in 10ths of chord of max camber
3rd/4th number: percentage of max thickness to chord
What is the formula for the Force due to circulation
F= ρvΓ
What is Cl roughly equal to?
Cl = 2πα
What is Cl roughly equal to for a non-symmetrical aerofoil?
Cl = Cl0 + 2kπα
Cl = kπ (α0 + α)
How does the continuity equation change when looking at the speed of sound in air?
ρvA = (ρ + ∂ρ) * (v + ∂v) * A = C
What is the equation for Mach number?
M = v/a
M = TAS/LSS
What is the equation for fluidity?
1/µ
