DISCUSSION OF SOURCE TERMS IN COMPUTATIONAL AEROACOUSTICS OF ANISOTHERMAL FLOW USING A LOW MACH NUMBER APPROXIMATION

摘要

A hybrid method is presented to compute the sound emitted by low Mach-number flows. The flow solver is a low Mach number approximation of the Navier-Stokes equations. It allows going beyond the incompressible approach by taking into account temperature and density inhomogeneities. The radiated sound computation is performed using linearized Euler equations. It is well known that these equations support unstable vorticity modes that can spoil the acoustic result. One way to avoid the vortical mode development is to not excite it. To do this, it is proposed to use the pressure gradient as a source term. This source term can be used for both isothermal and anisothermal flows. The method has been applied to isothermal and anisothermal excited shear layers. The validity of the proposed method is assessed by comparison to a direct noise computation. The isothermal case is presented here, the anisothermal case and temperature effects will be discussed at the congress.