Numerical Simulations of the Unsteady Flow and Radiated Noise Over a Cylindrical Cavity

Abstract

,The purpose of this paper is to investigate the acoustical field generated by the flow over a cylindrical cavity on a flat plane, similar to those located on wings and fuselage of transport aircraft, using a hybrid numerical method. Firstly, a CFD computation was carried out, using a Large-Eddy Simulation method, to compute the turbulent structures and the noise generating mechanisms. Secondly, the near-field results were injected in a Kirchhoff integral method code, in order to compute the far-field noise radiation. The retained case for this study is represented by a cavity with a unitary depth/diameter ratio, in the presence of a subsonic flow with a Reynolds number based on the diameter of the cavity equal to 4.6x10 5 . As inflow condition, a fluctuation-free velocity profile was considered. Computational results were compared to experimental data measured in an anechoic wind tunnel for the same geometry configuration, but in the presence of a turbulent boundary layer. As expected, a symmetrical flow pattern was observed joined with a fluid resonant mechanism. The computation shows that the acoustical field is less influenced by the inflow condition and results are in good agreement with the experimental measurements despite a slight under-estimation of the main tone amplitude.