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Calculator for Prandtl probe and Pitot tube flow velocity meter calculation

calculation of flow rate from the difference in total and static pressure

Prandtl probe is used as flow velocity meter and as flow rate meter, mainly for open flow around solid bodies. Flow velocity and flow rate measurement with Prandtl probe is based on measuring difference between stagnation pressure and static pressure of flow in a point of flow streamline. With Prandtl probe velocity meter in central part of Prandtl probe flow velocity is brought to zero isentropically. With velocity equal to zero measured pressure equals total pressure. On outer part of Prandtl probe where flow streamlines are tangent to Prandtl probe flow velocity is not changed and pressure measured on that part of Prandtl probe is called static pressure.

The difference between stagnation and static pressure in one point of flow streamline is called dynamic pressure. Dynamic pressure represents kinetic energy and flow velocity can be calculated using Prandtl probe calculator. Velocity is calculated as follows:

total pressure

where is:

  • p - pressure
  • pt - stagnation (total) pressure
  • pd - dynamic pressure
  • v - velocity
  • ρ - density

Calculator can be used for Pitot tube velocity meter as well. Pitot tube velocity meter is measuring stagnation pressure in one point of flow streamline and for known static pressure, dynamic pressure can be calculated and from dynamic pressure, flow velocity is calculated using Pitot tube calculator.

Calculator for Prandtl probe and Pitot tube flow velocity meter calculation can be used for liquids and ideal gases compressible and incompressible flow.

Related calculators for flow rate measurement with pressure differential devices:
Orifice plate calculator
Venturi tube calculator
Nozzle and Venturi nozzle calculator

More information about static, dynamic and stagnation (total) pressure (external links):
Static pressure
Stagnation - total pressure
Dynamic pressure