Effects of Active Control on Near-Field Pressure Fluctuations in Supersonic Rectangular Twin Jets*

Supersonic rectangular twin jets (RTJ) are of interest for current and future generations of tactical aircraft. However, the adverse effects of coupling have previously been documented to increase the near-field pressure fluctuations (NFPF) that can damage the nearby aft components of aircraft. In-phase coupling (IPC) is reported to be more damaging than out-of-phase coupling (OOPC). The focus of this work is to explore and control the coupling effects on RTJ NF pressure fluctuations by using localized arc filament plasma actuators (LAFPAs). The aspect ratio of the RTJ is 2, the design Mach number is 1.5, and the IPC or OOPC is shown to be along the minor axis. The results have confirmed that the pressure fluctuations in the inter-nozzle region, near the nozzles, were significantly higher for IPC than OOPC. The LAFPAs have shown great control authority by leveraging natural flow instabilities in the flow and the results have shown significant reduction in the near-nozzle pressure fluctuations switching from IPC to OOPC. The control authority and reduction in the near nozzle pressure fluctuations have been demonstrated over the entire flow regimes of overexpanded to design to underexpanded explored in this research. More detailed work is underway to further analyze the data.