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PREDICTION OF LOW-FREQUENCY TRAILING EDGE NOISE USING RAPID DISTORTION THEORY

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Experiments on the interaction between high Reynolds number jet flows and an external flat plate positioned above/beneath the flow [2, 3] have shown that the power spectral density of the far-field pressure (PSD) undergoes considerable amplification at low frequencies. For example, at the 900 observation angle, the low frequency amplification can be much as 10dB greater than the jet noise itself [2]. In this paper we present numerical results based on Rapid Distortion Theory (RDT) to model and explain this phenomena. The mathematical model is based on the formalism of [4] where the RDT equations of [5] and [6] are generalized to compressible transversely sheared base flows. Our results show that the RDT-calculated PSD for a rectangular jet flow is in reasonable agreement with the equivalent experiment [3] at low frequencies.

Author(s):

Mohammed Afsar    
NASA Glenn Research Center
United States

Marvin Goldstein    
NASA Glenn Research Center
United States

Stewart Leib    
Ohio Aerospace Institute
United States