Effect of turbulence on pressure probes

The mean pressure coefficients indicated by several types of static pressure probe and yaw meter have been measured in turbulent flow on the center line of a circular jet where the normal-component RMS turbulent intensity is about 0.24 of the mean velocity, for a range of yaw angles and a range of ratios of tube size to typical eddy size. For mean yaw angles greater than about 10 degrees , yaw meter calibrations differ significantly between turbulent and non-turbulent flow: this is because of the nonlinearity of the calibration at higher yaw angles, which are reached instantaneously. The response of a disc static tube, whose yaw calibration becomes nonlinear at quite small angles, is spectacularly altered by turbulence in the stream, and the use of this device in turbulent flow cannot be recommended.