Study on wake characteristics and power enhancement laws of helical vertical-axis wind turbines

The vertical-axis wind turbine can effectively enhance the urban renewable energy generation proportion, but suffers from low efficiency and unclear spatial layout rules. This study establishes a helical vertical-axis wind turbine model to explore wake characteristics and power enhancement laws. The accuracy of the model calculation results is verified by the comparison with the wind tunnel experimental results. The wake characteristics and power enhancement laws of the double helical vertical-axis wind turbines under different rotation directions, spacings, and relative placement angles are analysed. The results show that at a uniform inflow wind speed of 4 m/s, the power of the counter-rotating arrangement increases compared with that of the conrotatory arrangement. The average output power at 1.5d spacing increases by 15.82%, 31.26%, and 58.35% compared with that at 1.0d, 2.0d, and 2.5d spacings, respectively. The average power of the wind turbine at a relative placement angle of 45° increases by 7.56%, 31.92%, and 61.45% compared with that at 0°, 60°, and 90° angles, respectively. Therefore, the dual wind turbines achieve optimal output power under counter-rotating arrangement, 1.5d spacing, and relative placement angle of 45° conditions.