Improved analytical prediction of Boundary-Layer induced rotor noise using circumferential modes

Abstract

An improved theory addressing the interaction noise of a turbulent boundary layer with an open rotor is presented. Compared to a prior version, central components, such as the prediction of the turbulent velocity spectra, the correlation lengths and the stream tube contraction, are modified or included to better address the strongly anisotropic character of the boundary layer turbulence. The predictions with the improved theory shows a better agreement with some benchmark data with regard to the amplitude and spectral shape of the sound pressure signals.