Passive control of boundary layer flow separation on wind turbine blade using flow deflector

Flow separation frequently occurs in the inboard region of wind turbine blades, leading to degraded aerodynamic performance. A flow deflector (FD) is proposed as a passive flow control approach for wind turbines. The FD consists of a column of small flat plates mounted near the blade leading edge. Numerical simulations based on the transition SST model are conducted to investigate the flow control mechanism and its effects on blade flow structure and aerodynamic performance. The results show that the FD effectively deflects the local inflow toward the blade surface, guiding high-speed flow to energize the boundary layer. Therefore, flow separation is substantially suppressed, and both shaft torque and power coefficient are improved. The FD enhances sectional power output over 38.8% < r / R < 80.0%, extending beyond its installation region in the spanwise direction due to three-dimensional rotational effects. In addition, FD geometric parameters strongly influence blade aerodynamic performance. With an optimal FD configuration, the shaft torque and power coefficient increase by 18.24%, 20.77%, 7.90%, and 20.82% at wind speeds of 10, 11, 13, and 15 m/s, respectively.