Unsteady Inflow Of Jet To Rotating Bucket In Pelton Turbine

Hitherto, CFD (Computational Fluid Dynamics) has been widely used in the research of Pelton turbines to advance their hydraulic performances.In Pelton turbines, the internal water flow is so complicated of mixing with highly instability, that it is difficult to acquire the reliable numerical simulation for it. With the development of computer technology and CFD, the application of CFD to the research of Pelton turbines will have the significant importance to the analysis of flow mechanism and the design of Pelton turbines.The inner flow of Pelton turbine includes the mono-phase flow inside nozzle pipe, the free jet flow emerged from nozzle and the unsteady free water sheet flow on bucket surface. In order to prepare the theoretical basis of Unsteady Inflow of Jet to Rotating Bucket in Pelton Turbine, this paper firstly introduced the solution procedure of CFD, coordinate system and coordinate conversion,the production of 3-D BFG and natural basis vectors on 3-D free surface with every nodes.Discretion of three-dimensional free jet grids, directly affects the quality of numerical analytical results. This paper describes jet discretization of butterfly BFG, calculating dQ of every grid, computing landed points of free jet on the relevant bucket and relative velocity of every relevant landed point.On this basis,we can obtaine the unsteady border cut by the relevant bucket's cutout.The geometry of jet flow is necessary information to judge the quality of jet flow and helpful for the design of nozzle, needle and bucket. These parameters directly affect the unsteady inflow to rotating bucet and the relative trajectories with inflation free jet which cut by rotating bucket. With many advantages of animation analytical method in the unsteady jet relative trajectories, and based on this, 1-D relative trajectories of the unsteady jet to the splitter-tip, 3-D relative trajectories of 3-d unsteady jet to the cutout of the relevant bucket and 3-D unsteady jet TES catching up with the relevant bucket.On this basis, we get the moment iF _lastFull when the last completed jet drop into the bucket, the moment iF _last0 whne the last drop water drop into the bucket and 3-D unsteady jet flowed into the relevant bucket by the the analytic method.The time step is very small for the transient analysis of nozzle jet flow, which occupied numerous computational resources. In order to speed up the computation, the optimum numerical modeling, meshing and boundaries were discussed.Eventually the achievement and shortcoming in this paper were summed up. At the same time, the author took an outlook for the future research.