Calibration and Use of n-Hole Velocity Probes

A generalized calibration process is presented for multi-hole, pressure-based velocity probes which is independent of the number of holes and probe geometry, allowing the use of probes with large numbers of holes. The calibration algorithm is demonstrated at low speeds with a conventional seven-hole pressure probe and a novel nineteen-hole pressure probe. Because the calibration algorithm is independent of probe configuration, it is very tolerant of data corruption and imperfections in the probe tip geometry. The advantages of using probes with large numbers of holes is demonstrated in a conventional wing wake survey. The nineteen-hole probe offers a higher angular sensitivity than a conventional seven-hole probe, and can accurately measure velocity components even when an analytical calibration scheme is used. The probe can also provide local estimates of the diagonal components of the cross-flow velocity gradient tensor in highly vortical flows.