Liu, Y and Dowling, AP and Shin, HC and Quayle, AR (2007) Experimental study of surface roughness noise. 13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference).Full text not available from this repository.
A turbulent boundary-layer flow over a rough wall generates a dipole sound field as the near-field hydrodynamic disturbances in the turbulent boundary-layer scatter into radiated sound at small surface irregularities. In this paper, phased microphone arrays are applied to the experimental study of surface roughness noise. The radiated sound from two rough plates and one smooth plate in an open jet is measured at three streamwise locations, and the beamforming source maps demonstrate the dipole directivity. Higher source strengths can be observed in the rough plates than the smooth plate, and the rough plates also enhance the trailing-edge noise. A prediction scheme in previous theoretical work is used to describe the strength of a distribution of incoherent dipoles over the rigid plate and to simulate the sound detected by the microphone array. Source maps of measurement and simulation exhibit encouraging similarities in both source pattern and source strength, which confirms the dipole nature and the predicted magnitude of roughness noise. The simulations underestimate the streamwise gradient of the source strengths and overestimate the source strengths at the highest frequency. © 2007 by Yu Liu and Ann P. Dowling.
|Divisions:||Div A > Fluid Mechanics|
|Depositing User:||Cron job|
|Date Deposited:||16 Jul 2015 14:07|
|Last Modified:||02 Aug 2015 03:00|