Real-Time Adaptive Feedback Control of a Supersonic Dual-Stream Jet
Melissa Yeung, Yiyang Sun
TL;DR
This work develops a real-time, data-driven framework that combines online windowed dynamic mode decomposition with closed-loop LQR control to suppress a high-frequency resonant tone in a two-stream supersonic jet. By updating a time-varying linear model from sensor data and incorporating actuator constraints, the method targets instability-driven tone without heavily perturbing the mean flow, achieving substantial reductions in unsteadiness with reduced actuation energy. The results demonstrate that adaptive control can eliminate the dominant tone while preserving broadband flow features, and highlight the role of intermittent low-pressure events as major contributors to the tone. The approach offers a practical, sensor-geometry-robust pathway for active flow control in complex jet flows, with potential extensions to multi-actuator configurations and experimental validation.
Abstract
Adaptive control is applied to a supersonic dual-stream jet flow comprised of Mach 1.6 core and Mach 1.0 bypass streams that mix to form a supersonic shear layer. The vortices shed are the source of a high-frequency tone that persists throughout the flow. The intricate flow dynamics motivates the need for an elaborate and efficient actuation system to suppress the tone and weaken the propagating shock train. The present work utilizes online dynamic mode decomposition, which estimates the system dynamics as a locally linear evolution. Snapshot matrices are constructed using sensor measurements, facilitating economical and real-time computations, which are continuously updated and used in a feedback control model. Adaptive control is found to efficiently target the resonant tone with little disturbance to the mean features. The framework is not sensitive to sensor placements, enabling actuator design under physically realizable spatial locations in practical implementation. To reflect physical limitations, constraints are imposed on the controller model. It is found that the restricted controller yields greater vortex suppression due to repeated transitory stabilization of the shear layer instability. Statistical analysis reveals intermittent low-pressure events are responsible for the characteristic frequency, which are largely suppressed by adaptive feedback control.