Numerical Simulation And Model Test Research On Optimization For Flow Patterns In The Forebay Of Pumping Station

The forebay of pumping station is an important hydraulic structure, could be divided into two groups:forward-intake and side-intake. The flow patterns in forebay should meet the hydraulic conditions of well-distributed water, proper flow and vortex-free, in that the water can properly flow into the intake so as to provide good water conditions for pump. Bad flow patterns in the forebay could lead to reflux, vortex and disturbance of water flow, deterioration of water absorbing conditions of the pump, even could cause the pump difficulty to start, cavitation, noise and so on. Especially in river with high sediment concentration, bad flow patterns in forebay can result in silting and scouring at the bottom of the river. Thus, it is very important to raise the efficiency of pumping system and estimate the sediment deposition by engineering measures.A certain side-intake pumping station is taken as an example to simulate the flow patterns in forebay without engineering measure and with measures, such as, "Y" type diversion pier, "T" type diversion pier, bottom sill, widen bottom sill and diversion wall and so on. Through the study of the above conditions, the optimal engineering measure is adopted.Then, the theory of similarity is applied in model test. In model test, the streamlines of surface layers and bottom layers are drawn, the flow velosity is measured by using velocity instrument, and the velocity evenness is calculated as the basis of choosing engineering measures.In numerical simulation, the 3D models corresponding the six projects are established by UG (a modeling software), then unstructured grids are meshed and defining the boundary conditions are defined for each model. The flow patterns in the forebay are simulated by CFX. Meanwhile, the streamlines diagrams of surface layers and bottom layers are exported, flow speed evenness for all sections are measured. Through analyzing the results of model experiment and numerical simulation, it shows that the results obtained by numerical simulation are consistent with those by model test method.Finally, the results of model experiment and numerical simulation are analyzed and compared, such as the streamline diagrams of surface layers and bottom layers, the flow rate evenness of all sections, meanwhile, considering stability of engineering measures, scheme 3 ("T" type diversion pier) is the optimal engineering measures of the pumping station, which is very important to estimate the sediment deposition and ensure safe operation.