Acoustic Prediction Using Ffowcs-Williams/Hawkings Formulation based on a penetrable surface Implementation and validation with analytic solution

Abstract

In this report, the implementation of the new FW-H formulation based on penetrable surface into DLR APSIM code is discussed. The new formulation is briefly derived. The data preparations for using the new formulation are then discussed. An aeroacoustic benchmark problem based on a point monopole source is then derived. This benchmark problem will be used to validate both FW-H and Kirchhoff formulation. The results using different formulation are compared. Finally, the effect of an open integral surface on the radiated sound field is discussed and suggestions on the future works are then presented. The methodology of the APSIM is based on both classical FW-H formulations with impenetrable surface and Kirchhoff formulations. This code has been improved recently in order to allow for acoustic calculations based on CAMRAD computations of blade airloads under ECD requirements on APSIM. The code has also been adapted to accept the blade pressure distributions from DLR UPM-Mantic (Main and tail rotor interaction code) for the main/tail rotor interaction noise prediction.