In most of industrial applications, rotating machines are operated in presence of ducts or nearby obstacles as for cooling fans placed on the back of a cooling unit or aircraft Environmental Control Systems (ECS) fans located in ducts. The acoustic scattering by surrounding surfaces should be then taken into account in addition to the free-field acoustic radiation. The present paper proposes to combine an extension of Amiet's theory for trailing-edge noise with a BEM solver. The method is validated on a fan test case, investigated experimentally at the Universite de Sherbrooke, in which an automotive fan is located in a duct used as complementary scattering surface. The necessary inputs for Amiet's theory are obtained using a scale-resolved simulation of the test setup, from which the trailing-edge wall-pressure spectra at different positions along the blade span are directly extracted. The comparison of the experimental results with the numerical method proves the necessity to take surrounding surfaces as scattering objects into account.
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