Acoustic scattering by 3d poroelastic plates with swept trailing edges

Abstract

© 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.We perform acoustic scattering calculations by 3D poroelastic plates with swept trailing edges. A boundary element method (BEM) is applied to solve the Helmholtz equation subjected to boundary conditions related to the vibration of trapezoidal plates. This analysis is performed by rewriting the BEM boundary conditions in terms of the structural modes of the plate, which allows a direct solution of the coupled fluid-structure interaction problem. In order to accelerate the solution of the large dense linear systems from the BEM formulation, a wideband adaptive fast multipole method (FMM) is employed. The structural modes of the plate are computed either by a pseudo-spectral method or a finite element method. A parametric study is carried out for the 3D acoustic scattering problem where a model source is placed close to a swept trailing edge. Firstly, the noise scattering by a compact quadrupole source is analyzed for low and high frequencies. Results are shown for different plate configurations including rigid, porous-rigid, impermeable-elastic and poroelastic plates. Then, acoustic scattering by a jet-installation problem is presented where a turbulent jet wavepacket is placed under a poroelastic plate with a swept trailing edge.