Three-dimensional unsteady simulation of the runaway transient of the Francis turbine

Based on the Reynolds-averaged continuity and Navier-Stokes equations, and the moment equation of the rotation system in the accelerated rotary relative coordinate, the governing equations of flow in the runner region are obtained. The runaway transients simulation of the Francis turbine based on HL220 is made with RNG k-Ε turbulence models under 9 gate openings, detailed analysis is focused on the flow in the draft tube to getvariation of pressure distribution on projective surface against time and pressure fluctuation of all test points in the turbine.