Numerical Simulation of Emergency Shutdown Process of Ring Gate in Hydraulic Turbine Runaway

A numerical model that considers the interaction between the ring gate and its neighboring components was used to simulate the emergency shutdown process of a ring gate in hydraulic turbine runaway. The three-dimensional, unsteady Navier–Stokes equations with renormalization group (RNG) k-ε turbulence models, multiphase flow models, dynamic mesh, and sliding mesh technology were applied to model the entire flow passage of the Francis hydraulic turbine, including the spiral case, stay vanes, ring gate, guide vanes, runner, and draft tube. We present a detailed analysis on the working conditions of the turbine during its runaway quitting process, the inside and outside surface pressure distributions of the ring gate, the pressure and velocity distributions of the spiral case, stay vanes, and guide vanes at different gate openings, and the loading condition of the ring gate during its closing process. The theoretical basis for improving the dynamic quality of the transient process and for hydraulic designing and optimization is provided by analyses.