Passive Control of Boundary-Layer Separation on a Wind Turbine Blade Using Varying-Parameter Flow Deflector

Horizontal-axis wind turbines are widely used for wind energy harvesting, but they often encounter flow separation near the blade root, leading to power loss and structural fatigue. A varying-parameter flow deflector (FD) is proposed as a passive flow control method. The FD adopts varying parameters along the blade spanwise direction to match the varying local angle of attack. Numerical simulation using the transition SST k-ω turbulence model combined with the response-surface methodology are used to investigate the effect of the varying-parameter FD on the flow structure and aerodynamic performance of the NREL Phase VI wind turbine. The results indicate that optimal performance can be achieved when the normal position of the FD increases from the blade root to the tip, and the install angle of the FD should be greater than 62° at blade section of r/R = 63.1%. Furthermore, response-surface methodology was employed to optimize the deflector parameters, with analysis of variance revealing the relative significance of geometric factors (l1 > l2 > θ1 > θ2). Compared with the original blade, the shaft torque of the controlled blade with the optimal FD is improved by 24.7% at 10 m/s.