Use of a hot wire anemometer as a particle velocity detector in standing sound waves

It has been determined experimentally that the hot wire anemometer can, with restrictions, be used as a linear‐amplitude response particle velocity detector in a longitudinal mode standing sound wave. In the case of a straight filament proper orientation of both the hot wire and the velocity field are important. Maximum sensitivity is obtained for a horizontal hot wire in a vertically oriented particle velocity field, but the output of a hot wire inclined 45°/135° to vertical in a horizontal standing wave tube is phase sensitive to the sense of the particle velocity vector. High‐pass filtering is required to remove low frequency nonlinear components of the repetitive driveup–free‐decay amplitude modulation. Traverses of the particle velocity field near a 0.9525 cm diam sphere in a 5.08 cm i.d. cylindrical cavity are presented for both straight and curved hot wires.