Image Processing-Based Technique for Computation of Axial Sound Source Distribution in a Chocked Screech Jet

Abstract

A proposed technique to characterize the acoustic and flow fields during screech noise emission of a screech sonic jet is presented. Time-resolved visualization of the flow and acoustic fields under investigations are obtained using a high-speed schlieren optical system. Digital image processing of the acquired visualization is conducted and information on both the acoustic and flow fields is subsequently derived with Fourier analysis. The amplitude and phase of the screech tone in the near field are used to compute the screech-producing sound source distribution along the jet axis using the point source model proposed by Lee and Westley . The technique enables simultaneously the measurements of the screech tone frequencies emitted from the jet and characterization of the associated acoustic and flow fields.