水斗式水轮机基准斗安放位置对水斗性能影响研究

Study on the Influence of Reference Bucket Fixed Position of Pelton Turb

常规水斗式水轮机在设计过程中主要依据比转速、水头等参数,结合水轮机型谱、经验公式进行选型设计,在设计过程中未对基准水斗安放位置进行限制。本文通过对水斗式水轮机的选型过程进行分析,发现基准水斗不同安放位置对水斗性能具有重要影响,应在设计中予以考虑。采用ANSYS CFX流体仿真软件分析表明:水斗分水刃顶点、圆心连线与水平轴夹角的改变将引起转轮扭矩的变化,增加转轮扭矩的波动程度,使水斗内流态、水斗表面压力场偏离原始水斗,易造成切水边工作面压力降低引起局部脱流,水斗背面附壁效应增强引起水斗局部空化。该研究结果可为大型水斗式水轮机选型设计提供理论指导,提升冲击式水轮机设计水平。

In the design process of Pelton turbine,the type selection design is mainly based on specific speed,water head and other parameters,combined with the turbine type spectrum and empirical formulas.During the design process,there is no restriction on the fixed position of the reference bucket.Based on the analysis of the type selection process of Pelton turbine,this paper find that different fixed positions of the base bucket have an important impact on the performance of turbines,which should be considered in the design.The analysis using ANSYS CFX fluid simulation software shows the angle changes between the horizontal axis and the line of the vertex of the cut edge with the center of the circle will cause changes in the runner torque,increase the fluctuation extent of the runner torque.It also causes the flow state and pressure field on the bucket to deviate from the original bucket,which can easily lead to pressure unloading of the working surface at the cutting edge and cause local flow separation.It enhances the Coanda effect on the back of the bucket,causing local cavitation in the bucket.The research results can provide theoretical guidance for type selection design and improve the design level of Pelton turbines.