筒阀紧急动水关闭特性的数值模拟

为了防止水轮机飞选现象的发生，运用动网格和滑移网格技术，对动水关闭状态下的筒阀运动进行了三维非定常数值模拟和水力特性的研究．结果表明，筒阀的表面压力呈不均匀分布，引起的倾覆力矩最大值达2．94×10^4N·m．轴向力在筒阀关闭90％时达到峰值，并根据其变化的平稳程度提出了优化的筒阀关闭方式．此外，对筒阀表面的压力脉动进行了频谱分析，表明压力脉动的形成是尾水管涡带振动向上传递的结果．上述水力特性的分析不仅可以预测混流炎水轮机的工作状态．而且可以为筒阀运动的执行机构——多液压缸同步运动系统提供理论依据．

Numerical Simulation for Characteristics of Ring Gate During Emergency Shut-Down Water Process

Dynamic mesh and sliding mesh were used in order to perform three dimensional unsteady numerical simulation of ring gate during the emergency shut-down water process and study hydraulic characteristics to avoid runaway phenomenon. The result shows that there is uneven pressure distribution on the surface of ring gate with the maximum overturning moment value of 2.94 × 10^4 N · m. The axial force reaches its peak value at 90% closing. A better motion style is provided according to the variation of axial force. In addition ,the pressure fluctuation on the surface of ring gate was analyzed ,which reflects that it results from the upward transmission of eccentric vortex in draft tube. The analysis of hydraulic characteristics provide the forecast about working state of Francis turbine along with the design of multi-cylinder synchronous motion system.