Simulation And Control Study On Hydraulic Transient Process Of Complex Long-Distance Pumping Station Water Delivery System

Transferring water resources from the rich areas to the shortage areas through the inter-basin water diversion project is an important means to effectively solve the regional water shortage and realize the reallocation of water resources.When water conditions change,such as water flow adjustment,valve opening and closing,accident of pump station start-up or stop etc.,steady flow state of the water conveyance project destroyed,water would enter the hydraulic transition process and relative hydraulic parameters of water conveyance system would occurrence periodical fluctuations,in case of improper control,it is easy to have hydraulic parameters such as pressure and water level exceeding the design value and even lead to series of disasters or accidents such as structural damage,inundation and water abandonment of water conveyance project.Especially the pressurized conveyance system,which has the much more intense because of the high-speed water hammer wave.And when the pressure piping system of pump station is in the state of hydraulic transition process,water,mechanical and electrical system interactions would more complex and hydraulic control would be more difficult,which leading to the water conveyance project of pump complex long-distance water conveyance system to be a research focus in hydraulic control of draulic transient protection.Therefore,it is very necessary and important for engineering design and operation management to study the hydraulic transition process of long-distance and high-head pumping stations,analyze the hydraulic transient characteristics and study the hydraulic optimal control and protection methods.This article focus on the research on hydraulic transient process,based on the theory of water hammer and numerical simulation,illustrating with a certain example of complicated series-parallel pressure water conveyance system,"upstream reservoir-pump station-valves-connection well of water-keeping weir-downstream reservoir".First,the study built the connection with circular connection well of water-keeping weir as the boundary conditions of the new type hydraulic cohesive structure,which carried out continuous simulation of weir flow,well flow and other different flow patterns in hydraulic transient process,building one-dimensional transient flow model with characteristic method.Then,using CFD method to analyze the hydraulic characteristics of connection well under different flow states,the study discussed the quantitatively variation law of discharge coefficient and local head loss coefficient of circular connection well,providing hydraulic parameters for one-dimensional transient flow model of water-keeping weir boundary conditions.Finally,based on the above results,the study conducted research in numerical simulation of water hammer problems that may occur in long-distance water conveyance system,such as emergency stop,normal start and stop,valve opening and closing or other hydraulic transient process,putting forward hydraulic control principle of hydraulic transition process in complex long-distance water conveyance system,which aims at providing reference for the design and safety operation of pump station and water conveyance system.