水斗式水轮机喷射机构水力性能研究

Hydraulic performance of Pelton turbine injectors

水斗式水轮机喷射机构的主要作用是将水流的压力能转换为动能并形成高速射流,高速射流的质量直接影响着水斗式水轮机的能量转化效率。采用无网格运动粒子流方法对不同喷针开度下水轮机喷射机构的流量特性、喷针尖受力特性以及喷嘴出口射流流态分布特征等进行数值模拟研究。研究结果表明:随着喷针开度的增加,喷嘴出口流量逐渐增大,其增长率逐渐减小,喷针尖所受水推力逐渐增大;喷嘴出口射流自由液面逐渐出现发散现象,其表面变得不光滑。这与水力模型试验结果是相符的,验证了该方法的有效性,同时给水斗式水轮机的水力设计者提供了新思路。该方法可大大提高水力优化设计效率,具有一定的工程应用价值。

The main function of Pelton turbine injectors is to convert the pressure energy of the water flow into kinetic energy and form a high-speed jet.The quality of the high-speed jet directly effects the energy conversion efficiency of Pelton turbines.In this study,the meshless moving particle simulation method was used to numerically simulate the flow performance,the force characteristic on the needle tip,and flow distribution characteristic of the free flow surface of the injector outlet under different nozzle openings.The research results showed that as the nozzle openings increase,the flow discharge at the nozzle outlet gradually increased with a gradual descending increasing rate,and the hydraulic thrust on the tip of the needle gradually increased,moreover the jet flow at the nozzle outlet gradually diverged from the free flow surface,and its surface became rough.This is consistent with the hydraulic model test results,verifying the effectiveness of the method,and providing new ideas for the hydraulic designers of the Pelton turbines.This method can greatly improve the efficiency of hydraulic optimization design and has certain engineering application values.