Internal Fluidic Injection Using Sweeping Jet Actuator for the Control of Supersonic Jet Noise

This research investigates the efficacy of Sweeping Jet Actuators (SJAs) in mitigating noise in supersonic jets. A rectangular converging-diverging (CD) nozzle, characterized by an aspect ratio of 2:1 and a design Mach number of 1.5, was used. The nozzle incorporates an integrated secondary flow channel that supplies secondary air to the Sweeping Jet Actuator (SJA), facilitating precise air injection at various locations and configurations within the diverging section. Far-field acoustics were quantified using a microphone array, enabling the measurement of noise reduction in terms of the Overall Sound Pressure Level (OASPL) and spectra. Noise reductions were measured against the screech isolated baseline nozzle data. Schlieren visualization techniques were employed to elucidate the impact of the SJA on the structure of shock cells and the mixing of shear layers. Spectral Proper Orthogonal Decomposition (SPOD) was further utilized to analyze the influence of the SJA on the coherent structures of the jet. The implementation of SJAs resulted in a notable noise reduction of 3 dB in the downstream direction at a Nozzle Pressure Ratio (NPR) of 3.0.