Development and Application of a Quadruple Hot-Wire Technique for Turbulent Flows

Abstract

An analytical evaluation method to compute the instantaneous velocityvector from the signals of multiple hot-wire probes with nearly arbitrary geometry was developed. The domain of flow angles, in which for any given set of measured sensor voltages only one single solution for the instantaneous velocity vector exists, was determined for several probe geometries. Some measurement errors occurring in the components of the mean velocity and the Reynolds stress tensor due to the spatial separation of the sensors were estimated theoretically. The comparison of different three-sensor probes with a four-sensor Kovasznay-type probe shows that with the latter a significantly better accuracy in turbulence measurements should be attainable. Accordingly, a quadrupe-sensor probe was applied to measurements in the three-dimensional boundary layer on aninclined prolate spheroid model.