Vertical axis wind turbines (VAWTs) are experiencing a regained interest for use in large-scale offshore wind energy generation. However, the aerodynamic performance of lift-type VAWTs is lower than that of horizontal axis wind turbines. Setting a micro-cylinder in front of the blade leading-edge as a passive flow control approach is proposed to improve the aerodynamic performance of VAWTs. Numerical simulations combined with response surface methodology are conducted to find the optimal parameters of the micro-cylinder. The response surface optimization is performed on the DOE/Sanida 17m VAWT. The optimization variables of the response surface optimization model are the dimensions and positions of the micro-cylinder and the objective is the maximum tangential force of the VAWT. The optimal power coefficients of the VAWT with micro-cylinder are increased by 66.2%, 17.7% and 3.2% for tip speed ratios of 2.2, 2.49 and 3.09 compared with those of the original VAWT. The flow filed analyses show that the large-scale flow separations around the blade at large angles of attack are supressed by the vortex shedding from the micro-cylinder, which leads to an obvious improvement of torque coefficient for the VAWT with micro-cylinder.

vertical axis wind turbine,aerodynamic performance,numerical simulation,response surface methodology