Experimental Investigation on Acoustic Wave Generation due to Supersonic Hot Jet Impingement on an Inclined Flat Plate

In the present paper, noise generation due to supersonic hot jet impingement (M=۱.۴ and Tt=۹۵۰ K) to an inclined flat plate is experimentally investigated. In general, four types of acoustic waves are defined for jet impingement: acoustic waves generated by the shear layer of the main jet (type-A), by the impingement region (type-B), by the shear layer of the wall/jet downstream of the impinging region (type-C), and tonal acoustic waves observed in normal impingement. An attempt is made to understand the sources of the noise of the impinging jet by comparing acoustic scalograms of the impinging and free jets at the far-field. It is determined that the type-C acoustic wave images are similar to the far-field scalogram images of the free jet at the same polar angles. Further, the type-B acoustic waves in oblique jet impingement have similar acoustic signature with tonal noise due to normal jet impingement.

Keywords:

Hot jet impingement , Noise generation , Acoustic event , Feedback loop mechanism