CAA Slat Noise Studies Applying Stochastic Sound Sources Based On Solenoidal Digital Filters

Abstract

The present paper studies the application of a low-cost CAA approach to a slat noise problem. A new fast and cheap stochastic approach is introduced to model the unsteady turbulent sound sources in the slat-cove. It is based on the spatial filtering of a random white-noise field and incorporates information about the integral length scale and the turbulent kinetic energy from a steady RANS computation. The stochastic method, which stems from the LES inflow boundary condition proposed by Klein et al. that reproduces firstand second-order one-point statistics, is extended in this paper for aeroacoustic applications. The extended formulation yields a perfectly solenoidal velocity field that is capable to reproduce exactly the complete second-order two-point correlation tensor of homogeneous isotropic turbulence. Results for the sound generation at the slat are given for the underlying RANS mean-flow field being based on a Menter SST turbulence model with and without Kato-Launder modification, respectively. The results for the modeled turbulent flow-field and the radiated acoustic field exhibit physical meaningful characteristics.