Application of a Boundary Element reformulation of an aeroacoustical analogy based on incompressible flow data

摘要

We propose an implementation of the hybrid approach based on Curle's analogy, which formally describes the mechanism of sound generated by body-turbulence interaction. The acoustic propagation is carried out using an acoustic code based on the Boundary Element Method (BEM), in which scattering by arbitrary geometries can be computed, including impedance effects where needed. This was proved to give reliable results for cases where the body dimensions are fairly acoustically compact, and/or when the CFD model is accurate enough to capture the acoustical information over the turbulence-body interaction region. Difficulties arise however when the spatial extent of this region becomes comparable to, or larger than the acoustical wavelength, and when the flow data is provided by an incompressible model. A previous study has shown that a straightforward application of Curle's analogy to non-compact geometries, and in which acoustic source terms (in particular surface source terms) do not account for compressibility effects, can yield a poor estimation of the acoustical far-field. An innovative procedure is therefore developed and demonstrated on simplified cases.