Author(s)

F. Ajalli & M. Mani

Abstract

The unsteady separated turbulent flow around an oscillating airfoil plunging in a sinusoidal pattern in the regime of low Reynolds number is investigated numerically, employing the URANS approach with advanced turbulence model, k-ωSST transitional. A comparison with experimental data shows that the Transition SST model is capable of predicting the flow characteristics for the increasing cycle while the main difficulty lies in the accurate modeling of the complicated separated flows during the decreasing stroke. The flow development of the dynamic stall is also discussed. Keywords: dynamic stall, plunging airfoil, k-ωSST transitional model. 1 Introduction Dynamic stall has been widely known to significantly affect the performance of a large variety of fluid machinery, such as helicopters, highly maneuverable fighters, gas turbines, and wind turbines. It is well recognized that the dynamic stall process can be categorized into four key stages, i.e. attached flow at low angles of attack, development of the leading edge vortex (LEV), the shedding of the LEV from the suction surface of the blade and the reattachment of the flow [1]. Numerous experimental and computational investigations [2–5] have shown that the unsteady flow can be separating or reattaching over a large portion of the upper surface of the oscillating airfoil and that the predominant feature of the dynamic stall is the formation and rapid convection over the upper surface of the

Keywords

dynamic stall, plunging airfoil, k-ωSST transitional model