Multi-objective optimization of DBD plasma actuator characteristics for turbulent flow separation control over airfoils

Abstract

The optimal characteristics of a plasma actuator for effective control of high Reynolds number turbulent flow separation around airfoils are investigated. The actuator position on the airfoil and its voltage are chosen as variable parameters. A multi-objective optimization using a Genetic Algorithm is used with two objective functions of maximizing aerodynamic efficiency and minimizing power consumption. The numerical simulation of the plasma actuator effect on the flow is carried out using Maxwell equations for the electro-hydrodynamic (EHD) field coupled with Reynolds Averaged Navier-Stokes equations through the Suzen model. An algorithm is developed to automatically adjust the actuator position, generate the mesh, and analyze the flow for a Reynolds number of one million. A detailed analysis of the results revealed that the actuator position significantly impacts aerodynamic efficiency, depending on the airfoil type and voltage applied to the actuator. Further study is carried out to investigate the separation control by plasma actuator over two airfoils with similar thicknesses, i.e., NACA0012 and NACA4412. Results indicated that the optimal actuator position for the symmetric airfoil is the leading edge, while that of the cambered airfoil (NACA4412) is near the middle of the airfoil. Furthermore, increasing the voltage beyond a specific threshold results in a rise in the drag coefficient, thereby diminishing the aerodynamic efficiency. The optimization analysis ultimately demonstrated that the peak aerodynamic efficiency for NACA0012 and NACA4412 airfoils is achieved at distinct voltage levels, specifically 18 kV and 21–22 kV, respectively.