Perturbation-based active flow control in overexpanded to underexpanded supersonic rectangular twin jets

The effects of perturbation-based active flow control on supersonic rectangular twin jets (SRTJ) over a wide range nozzle pressure ratios (NPR = 2.77 to 6.7, corresponding fully expanded Mach numbers M j 1.3 1.9) were investigated. aspect ratio and design number for the bi-conic, converging-diverging nozzles 2 1.5, respectively. acoustic fields SRTJ are known couple, often generating high near-field (NF) fluctuations elevated far-field (FF) noise levels. Large-scale structures (LSS), or equivalently instability waves wave packets, responsible mixing noise, broadband shock-associated screech coupling. primary objective this research was manipulate development LSS in complex better understand mitigate their effects. organization passage frequency altered by excitation instabilities frequencies modes. Key findings include: (1) mode each jet flapping along its minor axis; (2) coupled, out-of-phase primarily overexpanded cases in-phase underexpanded cases, axis SRTJ; (3) coupling has significant NF fluctuations, but only effect FF noise; (4) standing observed plane (5) altering suppressing can significantly reduce fluctuations; (6) two high-frequency methods proved effective reducing (7) nonlinear interactions between tones input controlled which partially suppressed.