The First Experimental Model Results of H-type Darrius Vertical Axis Wind Turbine with Active Suction Cavity Blades

The present paper presents the first experimental model results of H-type vertical axis wind turbine with active boundary layer control. This was achieved by employing turbine blades with an active suction cavity technique to control the flow around the suction side of the blades. This technique was examined in previous study using computational models and proved to enhance the performance of this turbine type by preventing flow separation from the blade suction surface during the power producing half cycle of the blade. High-speed, battery-operated micro centrifugal air blowers were specifically designed and manufactured to provide the required suction flow from the surface cavities of each blade. The employed turbine had a solidity (Nc/πD) of 0.234 while the height/diameter ratio (H/D) is 1.25. All experiments were performed at a mean wind speed of 8.5 m/s. The corresponding Reynolds number, based on rotor diameter, is 4.2x10 ⁵ . Experimental results provided evidence that boundary layer flow control through active operation of suction cavities is a viable performance augmentation technique for the Darrieus VAWT. The generated power using suction flow showed up to 50% increase when suction flow is activated compared with the baseline turbine without suction effects. The net power coefficient of the system, obtained by subtracting suction blowers power from the generated power, is slightly better than the baseline turbine. It is recommended to employ higher efficiency suction system to enhance the net power coefficient.