Numerical investigation on the aerodynamic performance of vertical axis wind turbines utilizing a biomimetic fish tail paddle configuration

Inspired by natural phenomena, it has been observed that fish can freely maneuver their tails while swimming, allowing them to adjust their speed and direction with precision, thus controlling their swimming state. Drawing from this insight, a fishtail-like paddle structure was designed at the trailing edge of the vertical axis wind turbine wing. The extension length and deflection angle of the paddle were controlled at different azimuth angles through user-defined functions. Using computational fluid dynamics, the lift and drag coefficients, instantaneous torque coefficients, wind energy utilization coefficients, and flow fields of biomimetic fish tail structure airfoils and corresponding vertical axis wind turbines were analyzed. The research findings indicate that the blade can increase the surface pressure difference of the airfoil while simultaneously boosting torque, resulting in improved wind energy utilization coefficients for the vertical axis wind turbine across medium and low blade tip speed ratios (TSR). At a blade TSR of 2.63, with a deflection angle of 0° and an extended horizontal length of 0.4c, the biomimetic fish tail vertical axis wind turbine employing active flow control exhibited optimal aerodynamic performance, with its maximum wind energy utilization coefficient increasing by 18.9 % compared to the reference vertical axis wind turbine. This study offers valuable insights into the efficiency in practical engineering scenarios.