Development of Combined CAA-CFD Algorithm for the Efficient Simulation of Aerodynamic Noise Generation and Propagation

The purpose of this work is to develop efficient method for the prediction of aerodynamic noise generation and propagation in low Mach number flows in which dipole source, originating from unsteady pressure fluctuation on a solid surface, is known to be more efficient than quadrupole sources. This method is based on flow noise solvers using acoustic governing equations forced with immersed dipole source terms. The dipole source terms consist of point body forces immersed on each grid point on the solid surface. Their magnitudes are set by unsteady hydrodynamic pressure data previously calculated by incompressible Computational Fluid Dynamics Techniques. For comparison, modeled quadrupole source terms are also considered. These aeroacoustic solvers combined with CFD flow solver is applied to two-dimensional cylinder flow, which generate Karman vortex streets and resultant Aeolian tones. The properties and characteristics of sound generation process on and around the cylinder and of sound propagation through the background flows are analyzed in some detail.