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 stillwater. This simple in situ calibration method is principally beneficial for the investigations of threedimensionalboundary layers which are encountered for instance over rotating disks. In addition to thisproposed technique, an existing alternative method in which the calibration is performed against aknown reference velocity over a flat surface of a rotating disk is conducted. The comparison of both methodsshow that the rotating-arm technique is superior to that existing alternative flat-surface calibrationmethod.