β Scribed by M. CARLEY; J.A. FITZPATRICK
No coin nor oath required. For personal study only.
The e!ect of turbulent loading on the noise radiated by an advanced aircraft propeller is assessed using a spectral conditioning technique which allows the inclusion of the non-linear e!ects associated with source rotation. The method allows the steady-source noise at a microphone to be estimated by removing the e!ect of measured on-blade unsteady loading. The operation of the method is demonstrated by using numerically simulated data, demonstrating the e!ectiveness of the technique in extracting the steady-source sound. Experimental results are presented showing the e!ect of random loading on the acoustic "eld of a propeller in an axial #ow and at incidence. It is shown that, for the range of conditions and microphone positions considered, the e!ect of turbulent loading on the radiated noise can vary from about 2}8 dB, being stronger upstream than downstream.
2000 Academic Press
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