Analysis of CFD for The Vortex Rope in The Draft Tube Urged by The Long and Short Blades Runner

摘要

The RNGk-ε turbulence model is used to carry out the 3D steady turbulent calculation on the runner and draft tube of the Francis turbine. And the prototype of the Francis turbine is HLA351. Under 8 typical operating conditions, numerical simulation on how the runner outlet urge the vortex rope in draft tube are accomplished in this paper, and the calculation models are long blade model and mixed blade model. The results show that the runner outlet of the mixed model can lead the vortex rope location to the downstream relatively, reduce the circumfluence and cushion area and the probability of the second-vortex. What's more, the flow pattern in mixed model is superior to the long model and that benefits the operation stability and economy of the unit.