Numerical Simulation Of Turbulent Flow In Whole Flow Passage Of A Francis Hydro-turbine

As a core component of a hydropower station, hydraulic turbine plays a vital role in the integration of a Station. Research on the technology of hydraulic turbine is continuously increasing with the development of water electricity. However, in many domestic and foreign hydropower stations, due to some technical problems, the malfunction of the water-turbine generator set still exist, which may lead to the damage of flowing parts, The efficient and steady performance of Francis turbine has been taken into more consideration with its increase in capacity, size and speed. It is essential to do further research on the internal flow field simulation. Therefore, studies of steady and unsteady flow in hydraulic turbine components are of importance to deeply understand the hydraulic turbine vibrating intrinsic mechanism, improve the comprehensive hydraulic performance of the hydraulic turbine, and enhance the operating stability of the water-turbine generator set.Based on the Parameters of prototype Francis turbine in a hydropower station, this research established a geometric and physical model for full flowing passage of the hydraulic turbine. Firstly, the numerical simulation of complete components and coupled rotor-stator steady turbulence flow was conducted by RNG κ-ε model turbulence model under different head height conditions. The flow information in the Francis turbine was obtained, under different working conditions, analysis of internal flow characteristics of the turbine, the efficiency and cavitation performance were quantifiably analyzed and forecasted. Based on the steady turbulent flow is simulation, the unsteady numerical simulation of rotor-stator interaction was conducted by LES model turbulence model and sliding mesh technology. The turbine under the different condition, different time internal flows, parts of hydraulic turbine pressure pulsation were tested and analyzed. Through the above analysis shows that the results of the internal flow of the turbine is very complex and unstable turbulent motion, exists in the turbine runner hit off flow, cross flow and reflow phenomenon; In the draft tube eccentric vortex band. These are all hydraulic efficiency, stability and safety of the turbine will have a significant impact. The analysis of object is the water turbine runner, not for numerical simulation analysis of single components. Boundary conditions of whole passage simulation could be given more easily, compared with single component simulation. Calculation results were closer to those of the real situation. The simulation in the whole passage can make more accurate prediction of the performance.RNG κ-ε model and LES model can better simulate the turbine internal flow characteristics, but in the analysis for pressure fluctuation in draft tube, LES model of the flow calculation results more close to the real situation.