Study on Performance Improvement of Cross-Flow Wind Turbine with Symmetrical Casing

Cross-flow wind turbine has a characteristic of high torque coefficient at low tip speed ratio. Therefore, it is good for the self-starting. Furthermore, it is low noise and superior to stability so that it attracts attentions as the city type small-sized wind turbine for urban district. But the maximum power coefficient is extremely low as 10% compared with other small-sized wind turbines. In order to improve the performance and the flow condition of cross-flow rotor, a symmetrical casing with a nozzle and a diffuser was proposed and experimental research with two kinds of symmetrical casings was conducted. The maximum power coefficient was obtained as Cpmax=0.17 for the casing 2, however as Cpmax=0.098 for the casing 1. In the present paper, power characteristics of cross-flow rotor and one of a symmetrical casing with a nozzle and a diffuser were investigated. Then the performance and internal flow field of a cross flow wind turbine with the symmetrical casing were clarified. After that, the effect of the symmetrical casing on performance would be discussed with these results.