From LES via APE to trailing-edge noise

Abstract

This chapter focuses on a hybrid method to determine sound emission. The key elements of the concept are large-eddy simulations (LES) for the flow field and solutions of a system of acoustic perturbation equations (APE) for the sound field. A two-step approach has been used to predict the sound field generated by the subsonic flow over the trailing edge of a flat plate. A local LES provides the input data from the flow field for the sources, which excite acoustic perturbation equations. Internal sponge layers are introduced at the interfaces between the LES and APE domains to suppress spurious sound. The analysis of the pressure contours shows the hybrid concept in conjunction with the acoustic perturbation equations a reliable means to compute trailing-edge noise. Since the APE system contains convection and refraction effects the flow computation focuses just on the region where the sound is generated.