抄録
The vortical and separated flow field around a new type of wind turbine system called "wind-lens turbine" has been investigated by Reynolds Averaged Navier-Stokes (RANS) simulations. The wind-lens turbine has a diffuser with brim called "wind-lens", by which the wind concentration on the turbine rotor and the significant enhancement of the turbine output can be achieved. The Reynolds averaged Navier-Stokes equations were solved by an unfactored implicit upwind relaxation scheme with the k-omega two-equation turbulence model of Wilcox. Vortical flow structures were visualized by a semi-analytic method for identifying vortex cores based on the critical point theory. The RANS simulations and the flow visualization have been applied to conventional and optimum design cases of wind-lens turbine, in order to elucidate the relation between their aerodynamic performances and the flow fields around them. The numerical results show that large vortices are formed downstream of the wind-lens and they plays a major role in the wind concentration on the wind-lens. It is found that the aerodynamic performance of wind-lens turbine is significantly affected by the interrelationship between the internal and external flow fields around the wind-lens.
