Experimental model-based closed-loop control of a separated boundary layer at high Reynolds number

Abstract Experimental robust closed-loop control of a two-dimensional turbulent boundary layer with substantial separation is investigated. An array of 22 round fluidic jets located upstream of the separation location is used as actuation to reattach the flow. Measurements of phase-averaged velocity with 2D2C Particle Image Velocimetry (PIV) and wall friction using hot-film anemometry are performed to characterize the flow dynamics under open-loop actuation to elaborate models of the flow transient. Different feedback model-based controllers (Proportional Integral, linear–quadratic, linear–quadratic-gaussian and H ∞ regulators) are then designed and implemented experimentally. The performances in term of precision, reactivity and control cost of each of the controllers are presented and discussed. Only the H ∞ controller is found to maintain high performances despite large upstream unsteady perturbations.