Prediction of wall-pressure fluctuations using the statistical approach to turbulence induced noise (Satin)

The noise prediction model SATIN (Statistical Approach to Turbulence /nduced Noise) is presented. SATIN assumes axial symmetric turbulence with the length scale ratio λ and the Reynolds stress ratio ξ as two anisotropy parameters. The model is based on Lighthill's acoustic analogy and allows to predict both the far-field noise radiation as well as near-field wall-pressure fluctuations. In this paper, we focus on the latter because they are usually much larger in amplitude than far-field noise and therefore less sensitive to wind tunnel background noise. Experimental investigations of wall-pressure fluctuations under a turbulent boundary layer flow were done by TNOTPD. During the experiments, the flow velocity, the boundary layer thickness and the friction coefficient were varied producing different types of turbulent boundary layers. The wall-pressure fluctuations were measured with an array of microphones flush mounted in the wall. Predictions and measurements are compared on the basis of single microphone spectra. Input parameters of SATIN are characteristic values of the turbulent boundary layer, i. e. the boundary layer thickness and the friction coefficient or the friction velocity, respectively. These properties were extracted from measurements of the mean velocity distribution. The measured and predicted wallpressure fluctuations show good agreement. © 2001 by J. S. D. Ostertag, J. Golliard and S. Wagner.