Investigation of Active Flow Control on Aerodynamic Performance of HALE UAV Airfoil

Numerical studies were conducted to investigate the beneficial effects of using arrays of jets on the aerodynamic characteristics of the High-altitude Long-endurance Unmanned Aerial Vehicle (HALE-UAV) airfoil. Flowfield predictions were made by using an unsteady, two-dimensional, compressible Navier-Stokes flow solver. An unsteady surface transpiration boundary condition was enforced over a user-specified portion of the airfoil's upper surface to emulate the time-varied velocity out and into the airfoil's surface. Five flow-control techniques for the ¿quasi-Global Hawk¿ airfoil are investigated,as steady blowing, steady suction, unsteady blowing, unsteady suction and synthetic jets. A physical analysis of the influence on the control efficiency is proposed to provide some guidelines for practice. Our numerical results have indicated that active flow control techniques can, with the careful selection of their position and style, be used to enhance the aerodynamic performance of airfoils.