Study On Circulation Characteristics Of Open Channel Of Side Inlet/Outlet Of Pumped Storage Power Stations

With the increasing capacity of China's power grid,pumped storage power stations play an increasingly important role in power regulation by virtue of the advantages of high energy recovery efficiency,rapid response and long service life.Inlet/outlet as an important part of a power plant is directly related to the benefits of the power plant.As a link between the intake/outlet and the reservoir area,the excavation layout of open channel will directly affect the flow pattern in the open channel,and then affect the operation of the intake/outlet.Firstly,four types of open channel excavation layout are summarized.Based on four engineering examples,the circulation characteristics of open channel under four types of layout are studied by numerical simulation method.(1)The layout of the open channel of the intake/outlet is summarized.In view of the connection between the side inlet/outlet open channel and the reservoir area,four types of open channel layout modes are summarized.The fully open layout on both sides,the fully open layout on one side,the incompletely open layout on one side and the mountain layout on both sides.(2)Validation of numerical simulation method for intake/outlet open channel.The RNG-k-? turbulence model is used to validate the accuracy and rationality of the numerical simulation method by taking the open channel of the upper reservoir of Wendeng Pumped Storage Power Station as an example.(3)Study on circulation characteristics under intake conditions.The numerical simulation results show that the flow pattern in the open channel is the best under the fully open layout on both sides,and the velocity distributions of the two inlet/outlet trash racks are uniform and uniform;under the fully open layout on one side,there is no circulation in the open channel,and the velocity distribution of the trash rack cross section is uniform;under the incompletely open layout on the other side,there is a wider circulation in the open channel,the flow pattern of the three inlet/outlet trash racks is poor and the velocity distribution is not uniform.Under the layout of mountains on both sides,a small circulation is formed on the left bank of the open channel,but it has no effect on the inlet/outlet.(4)Study on circulation characteristics under outflow conditions.The numerical simulation results show that when the intake/outlet runs in full operation,there is no large-scale circulation in the open channel except for the backflow above the connecting section and part of the anti-slope section,and the flow gradually diffuses to the reservoir area.It shows that the layout of open channel has little influence on the circulation in open channel under the condition of outflow.However,when part of the intake/outlet is in operation(for example,three inlet/outlet are arranged side by side,only the middle inlet/outlet is in operation),there will be two opposite circulation in the open channel,but because the circulation is in front of the non-operational inlet/outlet and the flow velocity is low,it will not have adverse effects.(5)Study on optimization of circulation in open channel of inlet/outlet.The unfavorable circulation in the open channel arrangement with incomplete opening on one side not only affects the flow pattern in the open channel,but also reduces the uniformity of the flow in the sections of the trash racks of the inlet/outlet,which is an unfavorable flow phenomenon.In view of this situation,it is proposed that by enlarging the length of the connecting section of the open channel and enlarging the excavation area on one side of the open channel,the circulation position can be far away from the inlet/outlet,to some extent,the flow pattern in the open channel can be improved,the non-uniformity of the flow in the section of the trash barrier can be improved,and the adverse effects of the circulation can be reduced.The research results can increase the flexibility of inlet/outlet layout of pumped storage power station,avoid large-scale excavation,and provide reference for intake/outlet open channel layout.