Aeroacoustic analysis using a hybrid finite element method

Abstract

Abstract

This paper describes a novel three-dimensional analysis of tone noise radiated from turbofan inlets. This analysis combines a standard finite element (FE) discretization of the acoustic field in the axial and radial coordinates with a Fourier spectral representation in the circumferential direction. The boundary conditions at the farfield, fan duct, and acoustic liners are treated using the same spectral representation. The resulting equations are solved iteratively using an axisymmetric approximation of the inlet geometry to form an effective pre-conditioner. The analysis method is far less expensive than a conventional three-dimensional FE method because relatively few circumferential Fourier modes need to be retained for an accurate field representation.