Research On The Numerical Simulation Of Flow Patten In The Forebay Of Large Pumping Station

Forebay of Pumping Station is an important component part of the Pumping Station. It is a building which connects channel and into the pool. Its main function is to lead smoothly the water in the channel into pump's pipes, and create good working conditions for the pump. However, in certain situations it is possible to make flow in the bad flow pattern, such as deviation, detachment of wall, circulation, vortex and so on. These bad flow patterns will seriously affect the flow pattern in forebay, induce the decline of energy performances and cavitations property of pump, even cause vapour erosion of pump and vibration. Meanwhile backflow also lead to local sedimentation in forebay,which has further aggravated the development of bad flow pattern. So researching the improving measures of the flow pattern in forebay of pump station can enhance the pump's efficiency and decrease the sediment deposition, and can also have a significant meaning to the operational guidance of pump station and the enhancing economic performance.The main measures for regulating the flow pattern are determined by model trial method. The characteristic of this method is visual but use lots of fund and time. With the development of computational fluid dynamics and rapid improvement of computer capacity, it has been possible to research the pump station by numerical simulation. Numerical simulation can estimate the parameters that are difficult to measure in experiment. In the analysis and engineering design process of fluid machinery, numerical simulation improves reliability and reduces the cost significantly.This paper takes the front inflow forebay and side-direction inflow forebay of pumping stations in Jingdian Irrigation Area in Gansu Province as example,using Pro/E complete 3D entity modeling design of forebay and passage,hybrid grids cutting of forebay and passage made by GAMBIT.This paper sets up a 3-dimension steady incompressible turbulence flow model based on time averaged N-S equation and the standarddκ-εmodel, and simulates numerically this model by FLUENT,one of hydrodynamic computing softwares based on CFD.Taking water as the medium, the hydraulic characteristics of the original scheme of forebay is simulated through the change of working condition. Analysing its flow pattern of various working conditions to find the optimal open combination. First, the numerical simulation about flow pattern of the front forebay based on the various operating condition and different divergent angle; By contrasting the simulated results and experimental results, the mathematical model is verified According to the simulated result, the splayed diversion pier is putted forward, and a series of design parameter on the set-ups diversion piers are majorly computed to find the optimal design parameters. Second, the numerical simulation about flow pattern of the front forebay based on the various operating condition such as symmetrical open-type, dissymmetrical open-type, and all oen-type; it is shown by simulated results that, quantity of water contained sediment,shape of the forbey and various operating condition are main reasons which lead to the sediment deposition in side-direction inflow forebay. This paper suggests build a desilting sand trap or scientific management. Last, the results of the numerical simulating on the forebay hydraulic characteristic in the term of primary design agree with the test ones.