A New Hot-Wire Technique for Measuring the Instantaneous Velocity Vector in Highly Turbulent Flow

Abstract

Progress in developing a four-sensor hot-wire technique for measuring the instantaneous velocity in a high-intensity turbulent flow is reported. The measured velocity vector is accepted for data reduction in case a thermal wake detector identifies the vector to lie within a prescribed angular acceptance range. Measurements of mean velocities and Reynolds stresses in a turbulent boundary layer with large velocity fluctuations proved the method to be superior to standard hot-wire anemometry. The accuracy as well as the efficiency of the proposed measuring technique have substantially been increased by means of a new three-dimensional calibration procedure. Presently the four-sensor technique employing the new directional calibration is being used to investigate the flow field downstream of a normal flat plate; results of measured mean velocities and Reynolds stresses are discussed.