Optimized DBD plasma actuator system for the suppression of flow separation over NACA0012 profile

We address the problem of controlling the unsteady flow separation over an aerofoil, using plasma actuators. Despite the complexity of the dynamics of interest, we show how the problem of controlling flow separation can be formulated as a simple output regulation problem, so that a simple control strategy may be used. Different configurations are tested, in order to identify optimal positions of the actuator/sensor pairs along the aerofoil, as well as the corresponding references for the available real-time velocity measurements. A multi-objective deterministic particle swarm optimization algorithm is applied to identify the set of non dominated configurations considering as objectives the time-averaged input signal and the drag-to-lift ratio. Accurate numerical simulations of incompressible flows around a NACA0012 profile at Reynolds $Re=20,000$ and angle of attack 15° illustrate the effectiveness of the proposed approach, in the presence of complex nonlinear dynamics, which are neglected in the control design. Fast flow reattachment is achieved, along with both stabilisation and increase/reduction of the lift/drag, respectively. A major advantage of the presented method is that the chosen controlled outputs can be easily measured in realistic applications.