Control of airfoil flow at cruise condition by DBD plasma actuator: Sophisticated airfoil vs. Simple airfoil with flow control

We have conducted large-eddy simulations of the airfoil flow at a cruise condition con­trolled by a DBD plasma actuator. The NACA0015 is used as the airfoil. The Reynolds number and angle of attack are set to be 63000 and 4 deg., respectively. In this condition, the flow is almost attached, except for the separation bubble region, over the airfoil. The lift-to-drag ratio is improved by the flow control with the burst mode actuation. The most effective burst frequency becomes F⁺ ≃ 6 and the normal mode actuation is not effective. The delay of the turbulent transition is one of the key mechanism for the effective flow con­trol at the cruise condition, differently from the separation control case. The flow feature and aerodynamic performance are compared between the controlled flow and “Ishii airfoil” flow, which is developed as a low-Reynolds-number airfoil. The lift-to-drag ratio attained by the flow control is comparable to that of the Ishii airfoil. Moreover, it can be said that the flow control by the plasma actuator on the simple shape airfoil has the capability to emulate the flow feature of the sophisticated airfoil.