导流罩对潮流能水轮机效率提升分析

设置导流罩能提高潮流能水轮机效率,缩小转轮尺寸,降低机组造价。为了揭示导流罩聚能增效机理,采用VOF两相流模型对竖轴直叶潮流能水轮机进行三维模拟分析。即先根据模拟对象计算无导流罩情况下水轮机效率与尖速比的关系曲线,并对比加装导流罩前后的流态变化;然后分析导流罩各体型参数对水轮机获能效率的影响,通过正交分析得到使水轮机效率最高的体型。研究表明,导流罩通过提高转轮下游盘面流速来提高水轮机获能效率,其中导流罩喉部宽度对水轮机效率影响最大。

Improving Efficiency of Tidal Current Turbine by Adding Funnel-shaped Flow Concentrating Passage

Funnel-shaped flow concentrating passage can improve the efficiency of tidal current turbine, reduce runner sizes and cut down costs. To reveal the mechanism of this facility, we used 3D CFD method to simulate the efficiency of a vertical axis tidal current turbine with VOF two-phase model. Firstly, we introduced the simulation objects and methods, and find the relationship between turbine efficiency and tip speed ratio without the funnel-shaped flow concentrating passage. Then, we compared the differences of flow fields before and after the installation of the facility. Next, the impact of flow concentrating passage''s shape parameters on turbine efficiency was analyzed. Finally, the best flow concentrating passage which resulted in the highest efficiency was obtained through orthogonal analysis. It is shown that the facility increases turbine efficiency by increasing the flow velocity of the downstream part of runner, and the throat width is the most sensitive factor on turbine efficiency.