Computation of Wall Pressure Spectra from Steady Flow Data for Noise Prediction

Abstract

DOI: 10.2514/1.J050206 A method is proposed to calculate the trailing-edge broadband noise emitted from an airfoil, based on a steady Reynolds-averaged Navier–Stokes solution of the flowfield. For this purpose, the pressure spectrum on the airfoil surfacenearthetrailingedgeiscalculatedusingastatisticalmodelfromtheReynolds-averagedNavier–Stokesmean velocity and turbulence data in the airfoil boundary layer. The obtained wall-pressure spectrum is used to compute the radiated sound by means of an aeroacoustic analogy, namely, Amiet’s theory of airfoil sound. The statistical model for wall-pressure fluctuations is validated with two test cases from the literature, a boundary layer with an adverse pressure gradient, and a flat plate boundary layer without a pressure gradient. The influence of specific model assumptions is studied, such as the convection velocity of pressure-producing structures and the scale anisotropy of boundary-layer turbulence. Furthermore, the influence of the Reynolds-averaged Navier–Stokes simulation on the calculated spectra is investigated using three different turbulence models. The method is finally applied to the case of a Valeo controlled-diffusion airfoil placed in a jet wind tunnel in the anechoic facility of Ecole Centrale de Lyon. Reynolds-averaged Navier–Stokes solutions for this test case are computed with different turbulencemodels,thewall-pressurespectrumnearthetrailingedgeiscalculatedusingthestatisticalmodel,andthe radiated noise is computed with Amiet’s theory. All intermediate results of the method are compared with experimental data.