Formulas
Formulas
(OP)
G-Day,
Was looking for the formula to calculate "Velocity vs Pounds per square inch of pressure"
Was looking for the formula to calculate "Velocity vs Pounds per square inch of pressure"
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RE: Formulas
The other question here is "in what"? Typically the generalized equation is P=RQ Where P is the pressure drop through an object, such as a pipe. R is the resistance, and Q is the flow rate. The real problem here is "R" which can be non-linear and dependent on many parameters such as smootheness, shape, obstructons, Reynolds number, etc.
Regards
Dave
RE: Formulas
Looking for PSI, impact Pressure, say on an aircraft windshield or wing leading edge, vs velocity...
Example: Aircraft at 0 Mph, pressure 0 (relative to standing atmospheric pressure). Aircraft moving at say 60 Mph, what is the impact pressure on a 180 degree flat surface at that velocity...
Working on a RAT upgrade for my Cessna 172 to assist in my power use for my on board equipment... This RAT is internal with a Ram Air scoop in the slipstream under the aircraft... Need to compute the necessary size, compared to pressure of compression at velocity, to determine size of internal turbine system...
Randy
RE: Formulas
The airstream energy is 0.5 * M * V^2
E = #-ft/sec
M = mass flow (#/sec X 1/32.159)
V = velocity (ft/sec)
Consider the RAT as a stream tube where there is "E" energy in the airstream going in, Some energy is extracted by the RAT and other losses and the residual energy is exhausted out the back.
There should be information with the RAT to help here.
Regards
Dave
RE: Formulas
ratio of impact to free stream pressure=
[1 + (gamma-1)/2*M^2]^[{gamma-1}/gamma]
M=Mach no.
gamma= ratio of specific heats ideally air gamma=1.4
RE: Formulas
Clearly the pressure isn't constant on the plate face but you can get the average pressure (Force/Area).
RE: Formulas
Ps = Po + Rho x V^2/2
RE: Formulas
Ps = static pressure
Po = total pressure or impact pressure
Po = Ps + (1/2)*ρ*V2
Where ρ is mass density (kg/m3)
V is velocity (m/s).
Sailoday's equation gives the same answers (within 5%) as this equation for Mach numbers below 0.3, which is where the 172 usually flies.
RE: Formulas