冲击式水轮机水斗高应力区结构优化及加工

水斗高应力区的结构优化和高品质加工是保证冲击式水轮机水力性能的关键。建立了水斗有限元模型，并确定合理的边界条件；根据机组运行特点，确定水斗计算载荷工况，以及应力考核标准。同时在满足水力性能及强度要求的前提下，充分考虑水斗根部的可加工性。研究表明：斗根曲率均匀度、斗根深度和厚度是水斗应力水平的主要影响因素；通过水斗根部结构优化，水斗综合应力降低16%，交变应力幅值降低13.3%，交变应力平均值降低15.5%；通过强度计算验证了根部结构优化的水斗满足应力和疲劳设计要求。通过有限元和试验优化大长径比(20:1)减振刀柄中心孔尺寸，结果表明：当内孔直径为8 mm，振幅最小，通过试验验证和加工产品的实际应用，表明优化后的方案可满足设计结构水力性能及制造精度要求。

Structural Optimization and Manufacturing for Region of High Stress of Pelton Turbine

Structural optimization and high-steady machining of region of high stress play key roles for hydraulic performance of pelton turbine. Finite element model of bucket is established, and reasonable boundary condition are determined. Based on operation characteristics of pelton turbine, load cases and stress evaluation criteria of bucket are determined. Meanwhile, the manufacturability of the root of pelton is considered fully based on the requirements of the hydraulic performance and strength of pelton. The results of study shows that curvature uniformity of bucket root, depth of bucket root and thickness of bucket root are main factors influencing the stress level of bucket. By the structural optimization of bucket root, the compound stress, amplitude of alternating stress and average value of alternating stress are reduced by 16%, 13.3% and 15.5% respectively. The stress level and fatigue safety factor of the final bucket structure meet the design requirements. The size of inside hole of tool holder with larger aspect ratio (20: 1) is optimized through the finite element model and experiment, of which result demonstrate the lowest amplitude can be obtained when the diameter is 8 mm. The performance and machining accuracy of pelton turbine can be certified through the optimization strategy, which is validated by the experimental machining and the practical application.