Determination of the Reynolds-Stress Tensor With a Single Slanted Hot-Wire in Periodically Unsteady Turbomachinery Flow

Abstract

The pitchwise distribution of the components of the Reynolds stress tensor downstream of a rotating blade row can be obtained with a single slanted hot-wire and the technique of periodic sampling and averaging. The requirements imposed on the hot-wire and the sensitivity coefficients to the six stresses are given. Information concerning the electronic set-up and the problems associated with measuring the Reynolds stresses are discussed. It is shown that the sampling technique does not modify the mean square value of the sampled signal if the correlation time of the turbulence is smaller than half the sampling rate, or when the frequency bandwidth of the turbulence is higher than twice the sampling frequency. Typical results, including the 3D-mean flow data obtained downstream of a low-speed axial compressor rotor at different radii are presented. The results show typical modifications of the stresses in the rotor wake region and the regions influenced by secondary flow or tip-leakage flow.