Dual-Input/Single-Output Extremum-Seeking System for Jet Control

A dual-input/single-output extremum-seeking control system has been developed to manipulate a turbulent round jet based on a radially injected unsteady minijet. The Reynolds number Re-D, based on the nozzle diameter of the main jet, is from 5700 to 13,300. It has been demonstrated that this system may obtain rapidly and simultaneously the optimum excitation frequency f(e) and mass flow rate Q of the minijet, thus achieving the maximum decay rate K of the jet centerline mean velocity, as confirmed by the open-loop control results. This technique is robust to the parametric uncertainty with respect to Re-D within the tested range and adaptable when the initial control parameters are varied. It has been further found that the maximum K remains the same, be it a decrease or increase in Re-D, that is, the control performance is essentially independent of Re-D.