Performance and Flow Condition of Cross-Flow Wind Turbine With a Symmetrical Casing

A cross-flow wind turbine has a high torque coefficient at a low tip speed ratio. Therefore, it is a good candidate for use as a self-starting turbine. Furthermore, it has low noise and excellent stability; therefore, it has attracted attention from the viewpoint of applications as a small wind turbine for an urban district. However, its maximum power coefficient is extremely low (10%) as compared to that of other small wind turbines. In order to improve the performance and the flow condition of the cross-flow rotor, symmetrical casing with a nozzle and a diffuser are proposed and experimental research with the symmetrical casing is conducted. The maximum power coefficient is obtained as C_pmax = 0.17 for casing and C_pmax = 0.098 in the case without the casing. In the present study, power characteristics of the cross-flow rotor and those of the symmetrical casing with the nozzle and the diffuser are investigated. Then, the performance and internal flow patterns of the cross-flow wind turbine with the symmetrical casings are clarified. After that, the effect of the side boards set on the symmetrical casing is discussed on the basis of the analysis results.