Broadband Scattering of the Turbulence-Interaction Noise of a Stationary Airfoil: Experimental Validation of a Semi-Analytical Model

Abstract

A novel semi-analytical model based on Amiet's theory is proposed to predict the scattered acoustic field related to turbulence-interaction noise. The simulated scattered acoustic field is compared to the corresponding measurements of a stationary airfoil in a turbulent stream for validation purposes. The paper is composed of three main parts, where improvements and extensions of this semi-analytical model are presented. In the first part of the paper, a new formulation taking an intermediate level of geometrical near-field correction into account is derived. The second part provides an implementation of a strip method accounting for spanwise varying incoming flow conditions. The acoustic free-field response of the airfoil is computed using the geometrical near-field formulation with the strip method. In the third part, an innovative Boundary Element Method (BEM) approach is proposed in order to compute the scattered acoustic field of the airfoil by an obstacle. Finally, the scattered acoustic field resulting from the presence of a flat screen is computed by the semi-analytical method combined with the new BEM approach. A good agreement is obtained comparing with the measurements performed in an anechoic room.