ROBUST FEEDBACK CONTROL OF TWO AND THREE DIMENSIONAL FLOW SEPARATION AROUND A NACA0012 PROFILE USING PLASMA ACTUATORS

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. Accurate two-dimensional (laminar flow) and three-dimensional (turbulent flow) numerical simulations of incompressible flows on a NACA0012 at Reynolds Re = 20, 000 are performed in order to illustrate the effectiveness of the proposed approach. In the two-dimensional case a robust, fast flow reattachment is achieved, along with both stabilisation and increase/reduction of the lift/drag, respectively. The control system shows good dynamic performances, as the angle of attack is varied. For the three-dimensional test, a Large Eddy Simulation (LES) approach has been chosen for the modeling of the turbulence dynamics, whereas the eddy viscosity is calculated according to the well established classical Smagorinsky model. The adopted numerical algorithm is the in-house code ?navis, a general purpose tool developed at CNR-INSEAN, which is based on a finite volume formulation of the Navier-Stokes equations and is designed to handle complex geometries and free-surface flows. The aim of this paper is to show how, despite the high complexity of the system, a very simple robust output regulator is sufficient to effectively suppress the flow separation along an aerofoil, using DBD plasma actuators.