| CALC : Flow : Bernoulli 045 : Prandtl Tube Velocity From Pressure : Subsonic And Supersonic Compressible Gas Flow : Calculator
Description : Calculate the fluid velocity from the Prandtl tube pressure ratio for compressible flow in an ideal gas.
Discussion : The Prandtl tube pressure ratio can be used to calculate the Mach number of the flow under ideal gas conditions. The speed of sound can be calculated from the air temperature or user defined.
Options :
- Speed of Sound : calculated for ideal gas or user defined
Input Variables :
- γ = Gas Specific Heat Ratio
- A = Speed Of Sound Type
- Pp = Fluid Pitot Tube Pressure
- Ps = Fluid Static Pressure
- T = Fluid Absolute Temperature
- ad = Defined Sound Velocity
- mw = Fluid Mole Weight or Molar Mass
Output Variables :
- Ma = Fluid Dimensionless Mach Number
- Mk = Fluid Dimensionless Check Mach Number
- PoS = Prandtl Tube Pressure Ratio
- PoSs = Prandtl Tube Sonic Pressure Ratio
- V = Fluid Velocity
- a = Sound Velocity
Calculation :
PoS = Pp / Ps
PoSs = ( ( γ + 1 ) / 2 ) γ / ( γ - 1 )
If PoS <= PoSs
Ma = √( 2 / ( γ - 1 )( PoS( γ - 1 ) / γ - 1 ) )
Mk = Ma
Otherwise
list( Ma ) = MachGas( PoS , γ )
Mk = √( PoS( γ - 1 ) / γ ( ( 2 γ ) / ( γ + 1 ) Ma 2 - ( γ - 1 ) / ( γ + 1 ) ) 1 / γ 2 / ( γ + 1 ) )
End of If Block
If A = 1 : Ideal Gas
a = √( ( 8314.47 γ T ) / mw )
Otherwise If A = 2 : User Defined
a = ad
End of If Block
V = Ma a
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