Improving performance of twin counter-rotating vertical axis wind turbines under turbulent conditions: an integrated study using Taguchi method and large eddy simulation

Firstly, this study employs large eddy simulations (LES) and the Taguchi method to propose a baseline twin counter-rotating vertical axis wind turbine (VAWT) unit in turbulent conditions. LES simulations determine the power coefficient for each case, while the Taguchi method optimizes the design based on these results. Key design factors, including turbulent intensity (Iu), incoming flow angle (γ), turbine spacing (S/D), pitch angle (β), and aspect ratio (H/D), are selected for analysis. Range analysis ranks these factors by influence as γ > β > Iu>S/D>H/D, with the optimal configuration identified by the Taguchi method as Iu = 20 %, γ = 90°, S/D = 3.5, β = −6°, and H/D = 2.5. This setup achieves a rated average power coefficient (CP,avg) of 0.2564, surpassing the highest CP,avg (0.2476) among 16 orthogonal design cases, demonstrating the effectiveness of Taguchi method in optimizing twin counter-rotating VAWTs under turbulent conditions. The LES results also reveal reduced vorticity in the blades’ wake under turbulent flows compared to the smooth flow, suggesting that blade-shedding vortices have a diminished impact in turbulence. Secondly, a deflector (0.5D wide and 0.5H high) situated in front of the twin turbine is used to enhance the aerodynamic performance. This study highlights that the integration of the Taguchi method with LES can effectively optimize turbine performance while minimizing the need for extensive LES simulations.