Development of circular cylinder blade wind turbine driven by longitudinal vortex

It is known that the longitudinal vortex alternately and periodically forms diagonally backward of the upstream cylinder of the cruciform system consisted of the upstream cylinder and the downstream strip-plate and causes the strong periodic lift force on the upstream cylinder. We have had a new concept to form a longitudinal vortex steadily at a fixed position, in where the gap between the upstream cylinder and the strip-plate, and it generates a steady lift force on the upstream cylinder. A new wind turbine, which has a circular cylinder blade and is driven by the longitudinal vortex, has been designed by this concept. In this study, the flow-visualization by the smoke-wind tunnel confirms the generation of the longitudinal vortex that was predicted by the numerical analysis. The cross-sectional size of the vortex depends on the diameter of the circular cylinder blade and increasing the number of blades does not affect its size strongly. The steady lift force acting on the circular cylinder blade was measured and the relationship with the relative attack angle which is determined by the mainstream flow velocity and the moving velocity of the cylinder blade in crossflow direction was examined. At a small gap between the circular cylinder and the strip-plate, the fluid force acts to reduce the move. When the normalized gap by the cylinder diameter is larger than 0.35, the fluid force causes to accelerate the cylinder faster in the small relative attack angle region. The performance characteristics of the cylinder blade wind turbine were evaluated and they show the similar characteristics to the drag type wind turbine.