Optimization of a Francis Turbine Through Flow Simulation with a RNG k-ω Turbulence Model

摘要

In this paper, the optimization of a Francis turbine is carried out by the flow diagnosis method in the turbine runner based on vorticity parameters. Firstly, a new RNG k-ω turbulence model is proposed based on the RNG k-ε model, which brings the nonlinear term of the mean fluid flow transition to the ω equation in the original k-ω model. Secondly, the Reynolds-averaged Navier-Stokes equations are solved numerically by this RNG k-ω model. And, the prediction of the energy performances for Francis turbine is completed. Finally, the detailed flow behavior is revealed by vorticity parameters. In the paper, the simulation results for original and optimized Francis turbines have been compared as well. The model test results indicate that the efficiency of the optimized turbine will be improved from 93.6% to 94.5% in the case of optimum operating condition.