Extremum-Seeking Control of Subsonic Cavity Flow

An adaptive control system using extremum-seeking optimization is developed to suppress subsonic cavity ∞ow oscillations. The overall control system is developed by following two steps. First, a simple linear control law which uses measurements of wall pressure ∞uctuations at two difierent locations in the cavity is developed, and the efiect on the magnitude of the limit cycle produced by tuning its control parameters, namely a gain K and a phase shift `, is investigated analytically and experimentally. Then, an extremum-seeking algorithm is implemented to optimize the selection of the most critical control parameter, `, in real time, in such a way that the magnitude of the limit cycle is minimized in closedloop. A comparison with a linear-quadratic feedback controller based on a reduced-order model of the ∞ow dynamics is presented and discussed. Experimental results highlight the advantage of parameter adaptation provided by the extremum-seeking algorithm over controllers of flxed structure when operating in ofi-design conditions.