The Rolled-up and Tip Vortices Studies in the CFD Model of the 3-D Swept-Backward Wind Turbine Blades

In this paper, the method to analyze of vortex dynamics simulation of 3-D (three dimensional) backward wind turbine blades is introduced, consisted of flow visualization part and detailed measurement part. With this method, one could explain visually and by calculation the role of 3-D flow vortex mechanism patterns on 3-D backward wind turbine blade, the interchange between kinetic and potential energies, the utilization of very strong vortex, which could lose energy, generate lift, and produce tangential mechanical power. The method could be elucidated by analyzing the appearance of rolled-up vortex effect on the 3-D backward wind turbine blades. A sharp pointed backward blade, generally has a weak tip vortex, may generate a second weak vortex center, and appears due to the rolled-up vortex effect, which is quite difficult to identify. The weakness of tip vortex makes the sharp pointed blade more efficient to exchange energy. Blunt backward turbine blades generally have a strong vortex center, a tip vortex; which in the form of a vortex core. Due to the rolled-up vortex effect, it could generate a second weak vortex center that is clearly visible.