A critical evaluation of the explicit data analysis algorithm for a crossed wire anemometer in highly turbulent isotropic flow

Abstract

An experiment was conducted in a grid generated, nominally homogeneous, isotropic turbulent flow, in a wind tunnel of 0.33 m*0.33 m cross-sectional area, in order to evaluate the performance of an explicit non-real time data analysis algorithm for a crossed wire anemometer in highly turbulent flow. The 7000 data values acquired at various downstream locations with different turbulence intensities were analysed by the explicit non-real time method which assumes a constant yaw factor KT in the fixed angle calibration procedure, and by the 'look-up table' method which requires calibration at several yaw angles. It was found that the simple explicit non-real time method is adequate in computing the Reynolds stresses up a turbulence intensity of 40% when compared with the tedious look-up table method. The discrepancies are less than +or-6% for Reynolds normal stresses and less than +or-15% for Reynolds shear stress. A theoretical model based on the Gaussian probability density function was also developed to predict the probability distribution of the yaw angle of flow at various turbulence intensities in order to refine the explicit non-real time and look-up table methods of data analysis.