Numerical study of effect of solidity on vertical axis wind turbine with Gurney flap

Abstract

In order to increase the efficiency of straight-bladed vertical axis wind turbine (SB-VAWT), the inboard, outboard, two-side Gurney flap (GF) and dimple-GF are applied in SB-VAWT. The two-dimensional CFD simulation is utilized in this paper. Based on the validation of numerical simulation, the power coefficient, torque coefficient, vorticity field and standard deviation of fluctuation aerodynamic load of SB-VAWT are obtained. The results indicate that all kinds of GF can enhance the power coefficient in a certain range of tip-speed ratio (TSR). Compared to the clean SB-VAWT with solidity of 0.25, the outboard dimple-GF can increase the maximum power coefficient by 17.92% at TSR = 3.1. At all TSR, the two-side dimple-GF can obviously shrink the scale of trailing vortex and decrease the vorticity magnitude of trailing vortex. The outboard GF and dimple-GF can significantly increase the power coefficient of SB-VAWT with the different solidities at low TSR. When the blade number increases, the load fluctuation is reduced and the aerodynamic performance is decreased due to the intense interaction among the trailing edge vortices of multiple blades. A lowest load fluctuation is achieved at the blade number of 5.