Effect of Wind Shear on Characteristics of Rotating Blade of Field Horizontal Axis Wind Turbine

Abstract

This paper shows the aerodynamic characteristics at 50% radial section on a rotor blade of 10 m-diameter wind turbine is exposed to wind shear. A sonic wind speed meter and six cupanemometers are installed 1 D upwind of the turbine in order to measure wind profiles. The anemometers at the top, middle and bottom levels are installed at a height of 18.3, 13.3 and 8.3 meters respectively, which correspond with the height of tip at blade top position, hub height, and tip at blade bottom position, respectively. As results of the measurements, the normal force coefficient in strong wind shear condition decreases compared to those for weak wind shear condition. Even if local angle of attack is almost same condition, the normal force coefficient shows differences due to hysteresis effect. Especially, influence is large when not only a height direction but also a horizontal direction has strong wind shear. A remarkable difference appears in the pressure distribution at that condition.