Acoustic radiation from an engine intake using an admittance multimodal method

Abstract

This paper presents an adaptation of the admittance multimodal method for computing the mean flow around an engine intake and the associated radiated acoustic field. The basic idea is to surround the engine with a fictive duct with a perfectly matched layer on its outer wall which simulates far-field conditions and avoids any acoustic reflection. The use of matching conditions between this duct and the engine duct allows for calculating the flow and acoustic admittance matrices (and then the associated fields) everywhere. The developed method, initially devoted to acoustic propagation, can also compute the mean flow field with some adjustments and is very efficient if some assumptions are added (typically an incompressible flow hypothesis in the far-field). The flow and acoustic results are then compared against a finite element method and highlight the accuracy and efficiency of the proposed approach.