The response of static pressure tubes in turbulent flows

The parameters which affect the static pressure measured by Pitot tubes in turbulent flows are defined and corrections are indicated, considering the case of incompressible flow. The probe is regarded as being at a specific angle of attack in a uniform flow which is quasi-steady around the probe. The turbulent dissipation caused by the positioning of the orifice is shown to be a function of the viscosity, while the viscous dissipation has neligible effect. Attention is also given to the flow around the tube, the internal flow across the orifice, and pressure calculations in a turbulent flow. Static pressure measurements in turbulent free flows in a circular jet, in the wake of a cylindrical rod, in a plane jet, and in an unsymmetric jet are investigated for necessary corrections. Precise measurements are concluded to be possible if the profile of the instrument is small compared to the vortices, the probe stem has a smooth surface, the orifice is at least ten diameters from the support stem, and the tubes are not too far off the normal direction relative to the turbulence.