Estimation and closed-loop control of supersonic jet noise

The turbulent jet of an aircraft can generate noise exceeding 140 dB, posing serious health risks and underscoring the need for effective noise reduction strategies. Large-scale coherent structures in the form of wavepackets have been identified as primary contributors to downstream turbulent mixing noise, motivating wavepacket cancellation as a promising control approach. This work implements resolvent-based closed-loop control within a large-eddy simulation framework to suppress noise-generating wavepackets in a supersonic jet. The study proceeds as follows: first, the underlying estimation method is validated using a Mach 0.9 subsonic jet, with resolvent-based predictions compared against data-driven estimates of the downstream flow field using limited near-nozzle sensors. Second, large-eddy simulations of a Mach 1.5 supersonic jet are conducted, and data-driven estimation is used to identify sensor placement and target regions exhibiting improved performance. Finally, resolvent-based closed-loop control is implemented, and the controlled response is simulated using a linearized solver. Control effectiveness is evaluated through wavepacket suppression and corresponding reductions in near- and far-field noise. The results highlight the potential of resolvent-based estimation and control for mitigating jet noise.