The circular cylinder blades wind turbine is driven by steady lift force generated by longitudinal vortices formed in the gap between the rear ring flat plate and the cylinder blade. In this study, the turbine’s performance was improved by installing an additional flat plate on the front side. The front ring flat plate was found to increase the rotational speed under no-load conditions. However, under load conditions, the torque curve slope significantly decreased and the power coefficient Cp was reduced when the front ring flat plate diameter D'≦180mm. In contrast, when D'≧190mm, the torque curve slope was similar to that of the configuration without a front ring flat plate, and Cp improved. Notably, the configuration with D'=240mm achieved a maximum power coefficient Cp max approximately 2.5 times greater than that of the case without a front ring flat plate.
NAGASHIMA et al. (Wed,) studied this question.