超大容量水斗式水轮机水力特性数值模拟分析

An Analysis of the Hydraulic Characteristics of Huge Pelton Turbine by CFD Simulations

为满足超高水头、超大容量水电站建设需求,提出了一种额定水头1000 m,单机容量接近800 MW的三转轮立轴串联水斗式水轮机方案。阐明了这种通过增多转轮来增大容量的设计理念和结构组成,给出了方案的理论设计参数,并应用CFD模拟预测了其水力特性、分析和优化转轮及转轮室流态。研究表明:三转轮水斗式水轮机的额定工况效率可达87%,工作特性曲线变化平稳。转轮室溅水干扰是影响效率的主要因素。通过优化各层转轮相对位置和喷嘴方位,可一定程度提高效率,减小力矩振荡,保证出力稳定。此初步尝试证明了概念的可行性,也发现溅水优化的重要性,能为后续优化研究提供参考。

To meet the requirements of developing high head and huge capacity hydropower plants,this paper proposes a new Pelton turbine that joints three runners by one vertical shaft to have a rated head of 1000 m and a single unit capacity close to 800 MW.The design concept of increasing capacity by increasing the number of runners and the structural components of the new turbine-generator unit are explained,the theoretical design parameters of the runner are calculated and presented,the performance characteristics and the flow patterns in runner and casing are predicted and optimized by CFD simulation.The results show that the rated operating efficiency of the turbine can reach 87%,and the operating characteristic curves are smooth for different heads and outputs,the water splashing interference in the casing is an important factor affecting the efficiency of the turbine.By optimizing the layout of the runners and nozzles in the casing to suppress the splashing interference,the efficiency level,torque oscillation,and operation stability of the Pelton turbine can be improved.This preliminary attempt has demonstrated the feasibility of the concept and also found the importance of optimizing the water splashing in the casing,which has reference values for further researches.