Effects of wind gusts on the aerodynamic performance of a vertical-axis wind turbine with variable pitch

Numerical simulations are conducted to study the effects of wind gusts on the aerodynamic performance of a two-dimensional variable-pitch vertical-axis wind turbine. The influence of gust period, gust amplitude, and average tip speed ratio on the aerodynamic performance and the power coefficient of wind turbines is systematically analyzed. Results show that under gust conditions, the power coefficient of the wind turbine initially increases and then decreases as the gust period increases, reaching its maximum value at a gust period of 5. The maximum power coefficients for both standard gust and negative gust are achieved at a gust amplitude of 8 m/s. The power coefficient attains its maximum value at a mean tip speed ratio of 0.5, corresponding to values of 0.37 and 0.30 for the standard gust and negative gust, respectively. Proper orthogonal decomposition is employed to perform modal decomposition of the flow field under both gust and uniform flow conditions, which reveals that gust-induced unsteadiness increases flow complexity compared to uniform inflow.