Influence of blade overlap and blade angle on the aerodynamic coefficients in vertical axis swirling type Savonius wind turbine

TLDR: In this paper, the influence of blade overlap, blade arc angle and the diameter of the hot air inlet hole on the torque and power coefficient of a Savonius wind turbine was investigated.

Abstract: When compared with other wind turbines, drag driven vertical axis Savonius wind turbine offers lower power coefficient due to its slow turning speed. However, they have many advantages over others, such as simplicity of manufacturing, ability to operate in any wind direction, and having a good starting torque at low wind speed. They are well suited to be integrated in urban environment as small scale power generating wind mills. Waste heats or naturally available heat sources such as geothermal and solar energy can be utilized to produce swirling flow when there is a source of angular momentum. Previous computational work suggests that the performance of Savonius turbine can be improved by providing a hot swirling flow inside the turbine chamber. The swirling flow can be induced by a design similar to that of split channels, which includes one or a few vertical slits, and is currently used to onset fire whirls in the laboratories. In the present experimental study, the influence of blade overlap, blade arc angle and the diameter of the hot air inlet hole on the torque and power coefficient have been investigated. The results indicate that the maximum power coefficient for a 258 mm diameter rotor occurs at 28 mm blade overlap, '195°' blade angle and 9 mm diameter of hot air inlet hole.