Active Far-Field Noise Control of a Supersonic Rectangular Single Jet

The far-field acoustics of a supersonic rectangular single jet (SRSJ) were studied, and the flow was subjected to active flow control by plasma actuators. The nozzle design is similar to those used in previous twin jet experiments by our group in the Gas Dynamics and Turbulence Laboratory at The Ohio State University. It is a converging-diverging nozzle with a design Mach number of 1.50, an aspect ratio of 2, and features a biconic inner contour. The far-field noise of the baseline jet was characterized from equivalent jet Mach numbers (Mj) 1.30-1.70, then a wide variety of excitation frequencies and modes were explored at strongly screeching Mj = 1.40 (Case 1) and weakly screeching Mj = 1.50 (Case 2) to observe their effect on the jet acoustics. Excitation near the peak shear layer mode frequency (Ste ~ 1.50) produced significant noise reduction across all polar angles. In Case 1, over 2.5 dB of reduction around the peak far-field noise angle was observed, and in Case 2, the reduction was more modest (up to 1.7 dB) and occurred at higher polar angles.