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The Effect of Turbulence on a Multi-Hole Pitot Calibration



Christopher J. Crowley, Iosif I. Shinder, Michael R. Moldover


Abstract- Accurate calibrations of multi-hole Pitot tubes require thousands of measurements spanning ranges of the fluid’s velocity, and the pitch and yaw angles. When calibrating a commercially-manufactured multi-hole Pitot tube in NIST’s low-turbulence wind tunnel, we found hysteresis in certain ranges of airspeed, pitch angle, and yaw angle. In the worst case, the hysteresis caused a calibration error of 30 %. We demonstrate that the hysteresis was caused by a flow instability associated with flow separation. A turbulence intensity of only 1 % removes the hysteresis; however, the calibration dependends on the turbulence intensity over the entire range of our measurements (0.25 % to 2 %). Therefore, multi-hole Pitot tubes should be calibrated and used at the same turbulence levels.
Flow Measurement and Instrumentation


airspeed calibration, multi hole Pitot tube, detached boundary layer, and Turbulence.
Created June 10, 2013, Updated February 19, 2017