Impacts of Gurney flap and solidity on the aerodynamic performance of vertical axis wind turbines in array configurations

To improve the overall performance of VAWT farm configurations, the impacts of Gurney flap (GF) and the parameter of solidity on the performance of VAWTs in three-turbine arrays are investigated via computational fluid dynamics (CFD) simulations after a validation of computational model using experimental data in the present study. The results indicate that with the tip speed ratio (TSR) of the upstream pairs of VAWTs in array staggered configurations increasing, the flow velocity through the gap is higher and the upstream pairs of VAWTs achieve higher power output at high TSR compared to an isolated turbine. Then, the addition of GF on the upstream pairs of VAWTs can achieve higher flow velocity through the gap compared to the upstream clean coupled VAWTs, which is beneficial to the power output of downstream rotor. The downstream turbine in the configurations which consists of three GF-VAWTs achieves the best aerodynamic performance at TSR < 3.1, and at TSR = 2.51, this downstream rotor enhances the maximum average torque by 36.5% and 24% in comparison with the isolated clean turbine and the isolated GF-turbine respectively. Moreover, the downstream VAWT in array configurations with each solidity obtains higher power extraction than the isolated counterpart at overall TSR. At TSR = 2.27, the downstream rotor with a chord length of 123.5 mm achieves the increment of 23.1% in comparison with isolated counterpart.