Modification of Leishman–Beddoes model incorporating with a new trailing-edge vortex model

Abstract

The Leishman–Beddoes (L-B) model for airfoil dynamic stall is widely used in both helicopter rotor and wind turbine aerodynamics because it has fewer parameters and specific physical conceptions. However, in some cases of airfoil dynamic stall, the differences between the calculated results and experimental data are obvious, especially for the reattachment of airfoil dynamic stall. In order to observe the characteristics of dynamic stall about rotor airfoil, some dynamic stall experiments by PIV technology and CFD simulations based on RANS equations are accomplished. As a result, a trailing-edge vortex is observed which is not considered in the present L-B models. To consider the effect of this trailing-edge vortex on the unsteady aerodynamic characteristic, a new model of trailing-edge vortex is presented in this paper. In this method, the normal force induced by trailing-edge vortex is calculated by a similar methodology as leading-edge vortex, and the moment is modified due to the trailing-edge vortex. Consequently, the aerodynamic loads calculated by the modified L-B model at different reduced frequencies, Mach numbers, and airfoils are closer to the experimental data in the reattachment of dynamic stall. Therefore, it is demonstrated that the new trailing-edge vortex model further reflects the essence of trailing-edge vortex during the process of dynamic stall.

Keywords

Dynamic stall model trailing-edge vortex PIV experiment CFD helicopter airfoil

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