Numerical simulation of gusts over multi-element airfoils and their flow control

Various numerical simulation techniques, such as finite-volume cell-centered method, dual-time stepping method, moving overset grid method and grid speed method, were used to implement the numerical simulation of unsteady viscous flows over multi-element airfoils in gusts. Effects of a swinging flap on aerodynamic forces were studied, and the control law of the flap as well. The method used in the paper was first validated by comparison with the theoretical solution of NACA0006 airfoil under gust. Then a GW-2 airfoil with 30% flap was simulated under a periodic gust perpendicular to the incoming flow. The result shows that the lift of the multi-element airfoil changes periodically with time, the change of flap lift has the same frequency with the gust, and the lift fluctuating amplitude is in proportion to the gust amplitude. Further study shows that by properly changing the gust oscillating amplitude and phase, lift fluctuations of the airfoil can be brought under control.