It is generally recognized that the interaction of vortices with downstream blades is a major source of noise production. To analyze this problem numerically, a two-dimensional model of inviscid flow, together with the method of matched asymptotic expansions. is proposed. The method of matched asymptotic expansions is used to match the inner region of incompressible How to the outer region of compressible flow. Because of incompressibility, relatively simple numerical methods are available to treat multiple vortices and multiple bodies of arbitrary shape. Disturbances from these vortices and bodies propagate outward as sound waves. Because of their interactions, either constructive or destructive interference may result. When it is destructive, the combined sound intensity can be reduced, sometimes substantially. References: 21
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