Rotating-arm method for low speed calibration of hot-wire probes in water applications

Abstract

An instrument for calibration of hot-wire probes at very low velocities in water applications is introduced. The technique is based on moving a hot-wire probe by means of a rotating-arm device in still water. This simple in situ calibration method is principally beneficial for the investigations of three-dimensional boundary layers which are encountered for instance over rotating disks. In addition to this proposed technique, an existing alternative method in which the calibration is performed against a known reference velocity over a flat surface of a rotating disk is conducted. The comparison of both methods show that the rotating-arm technique is superior to that existing alternative flat-surface calibration method.