Effect of blade number on flow around straight-bladed vertical axis wind turbine

The influence of flow field and aerodynamic forces on a straight-bladed vertical axis wind turbine

“…The tangential force F T and the normal force F N are basically the difference between the tangential components of lift and drag forces. From these relations, the expression of F T and F N can be determined as following [15,18,46]:…”

“…Torque (T) acting on single blade can be expressed as [15,18,37]: The amount of power for the number of blades (N) and the power for upstream (P u ) and downstream (P d ) that can be absorbed from wind by a wind turbine obtained respectively from the following expressions [43,46]:…”

“…Wind turbine rotor performance is usually characterized by its power coefficient, C power [3,15,18,46]:…”

“…D is the rotor diameter of wind turbine, and H is the height of blade. As a result, the power coefficient represents the aerodynamic efficiency of the wind turbine and a function of the tip speed ratio l as [3,15,18,23,38,50,51].…”

“…Furthermore, it can reduce the transmission losses due to proximity to the demand center. There is an urgent demand of this type of wind turbine with high efficiency and low cost in urban areas [17,18]. Therefore, the design research on straight-bladed VAWT became one of the hot spots in recent wind power technology development.…”