Prediction of trailing-edge noise for separated turbulent boundary layers

Abstract

This paper presents a semi-empirical low-order prediction of the trailing-edge noise of separated turbulent boundary layers. The prediction focuses on obtaining the low-frequency spectral peak of the far-field sound pressure level by modeling the measured wavenumber- frequency spectrum using regression analysis and integrating that spec- trum in the manner of Howe’s radiation model. Surface pressure fluc- tuations upstream of the trailing-edge of a DU96-W-180 blade section were measured using miniature pressure transducers, and the trailing- edge noise was measured using a directional microphone. The prediction showed that the far-field sound pressure level reached its maximum below the frequency limit of the directional microphone measurement, between 400 Hz - 500 Hz depending on the freestream velocity and the predicted spectrum varied between ±0.5 dB given the inaccuracies of the regression model.