A user-friendly pitot probe data reduction routine for non-ideal gas flow applications

This contribution presents a user-friendly and robust data reduction routine for Pitot probes which can be realized using widely available software. The routine rests on the general balance equations and a database for calculating the thermodynamic properties of the involved fluids. In the present study, the proposed data reduction routine has been established as a calculation sheet using common office software and REFPROP by NIST. In the calculation sheet, the user can easily select the fluid and, manually or automatically, insert the recorded Pitot probe data and stagnation conditions. A robust algorithm directly calculates the freestream Mach number and other flow and thermodynamic quantities. The new Pitot probe data reduction routine's accuracy is assessed through several test cases, including the subsonic and supersonic flow of dry air, Novec 649, and Siloxane MM in the dilute and dense gas regime. For compressible non-ideal gas flows, it is found that the classical Rayleigh-Pitot equation is systematically in error even in the dilute gas regime where relative deviations of more than 10% are noticed. In the dense gas regime, the Rayleigh-Pitot equation fails dramatically in calculating the freestream Mach number, and errors larger than 60% can occur. •A Pitot probe data reduction routine is proposed, based on office software and a fluid database.•The accuracy of the Pitot probe data reduction routine is assessed through several test cases.•Substantial errors can occur if the classical Rayleigh-Pitot is used for non-perfect gases.•Especially in the dense gas regime, the ideal gas assumption fails for Pitot probe data reduction.