Flow Field and Acoustic Studies on a Supersonic Jet with Tabs Having Various Cross Sections

Abstract

Experiments were carried out over an imperfectly expanded supersonic jet at various nozzle pressure ratios with and without tabs of various cross-sectional shapes. The tabs used in the present study have either triangular, square, or circular shapes, placed circumferentially at three locations, 120° apart. In this study, shock waves were captured using the Schlieren visualization technique, and pressure measurements across the jet flow in both streamwise and cross-stream directions were conducted using an in-house built Pitot tube. Acoustic measurements were also made to capture the signature of jets with different shapes of tab cross section inside an anechoic chamber. The methods indicated the influence of tab shape on the downstream characteristics of the jet, including its core length, width, and tone. Different tab shapes resulted in significant alterations in the jet characteristics, which were also observed to be dependent on the nozzle pressure ratio. A complete alleviation of screech tone was recorded with use of tabs in the jet nozzle.