Validation of a three-dimensional mapping scheme to couple mean flow data to high-order acoustic propagation solvers

© 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. In a hybrid computational aeroacoustics method, the propagation of aerodynamically generated noise is computed using a three step procedure. The first step solves the aerodynamic problem, considering only the (usually reduced) sound generation area, with a technique from computational fluid dynamics. Subsequently, an interfacing scheme is used to transfer the relevant quantities of the aerodynamic solution, such as the mean flow features or the sources of sound, to an acoustic propagation solver. This solver is used in the third step to compute the acoustic propagation in the (generally larger) propagation domain. Since the characteristic length scales of the aerodynamic field and the wave propagation can differ by several orders of magnitude, the grid for flow dynamic computations is typically much more refined than the mesh used for the acoustic propagation. For this reason, a mapping methodology is needed that allows an accurate representation of the aerodynamic features on the sound propagation mesh. In this paper, an interfacing scheme for mapping non-uniform mean flows in three-dimensional acoustic propagation problems is presented. The mapping is based on a global least squares procedure to suppress spurious oscillations and to ensure continuity between the elements. Furthermore, a weighting function is added to deal with thin boundary layers in confined flow applications. To validate the proposed technique, the acoustic propagation through a duct with a rectangular cross-section has been simulated using the linearized Euler equations. The multi-port characteristics, obtained from these simulations, are in good agreement with the analytical reference solution.

ISBN:9781624105043

Publication year:2017

Accessibility:Closed