Study On Hydraulic Transients Of Long Distance Water Transfer Project

Long distance water transfer project often takes the form of the combination of open-channel flow, pipe flow and pumping station. The hydraulic transients of open-channel flow, pipe flow and pumping station interact with each other, so the whole research of the hydraulic transients is very necessary and important. According to the Project of Water Transfer from Luanhe River into Tianjin City(PWTLRTC), this paper divides the Project into two subsystems—open-channel flow-surge tank-pipe flow and cascade pumping stations and computes the hydraulic transients of two subsystems respectively.Based on the theory of open-channel flow transients and pipe flow transients, this paper adopts the method of characteristics with the same format to compute hydraulic transients of open-channel flow and pipe flow, and thus simplify the process of programming. Mathematical models of open-channel flow-surge tank-pipe flow and cascade pumping stations are developed respectively, and the mathematical models are used to compute hydraulic transient processes of many control working conditions. According to the characteristic in the computation of hydraulic transient process of long distance water transfer project, the different time step is applied to deal with the conjunction boundary of tranquil flow and critical flow and the conjunction boundary of open-channel flow and pipe flow. Compared with the same time step method, the varying-time step method can reduce the amount of computation and is easy for programming. So the varying-time step method can simulate the hydraulic transient process in practical project better.Hydraulic model test is carried out to study the local hydraulic characteristic. The model test result is used to the boundary of the mathematical model. The combination of physical model and mathematical model is an effective method to study the hydraulic transient process of complex water transfer system.