Solution Method of Water Hammer Boundary Conditions for Complex Connecting Valve Groups of Parallel Water Conveyance Pipelines

The solution method of water hammer calculation boundary condition of the complex connecting valve groups of parallel water conveyance pipelines is studied. Through the calculation formula of valve coefficient,the series or parallel valves are simplified into a single valve,so the connecting valve groups composed of multiple parallel valves are simplified. Based on the characteristic method of water hammer calculation and the valve flow formula,the nonlinear equations for the boundary conditions of the simplified connecting valve groups are obtained,and the methods of directly solving or iteratively solving the nonlinear equations under different valve opening or closing states are given. For a large gravity flow water conveyance project,the water hammer calculation of cutting off the water conveyance of some pipe sections by opening or closing the complex connecting valve groups in the normal maintenance process is carried out. The calculated hydraulic fluctuation has good continuity and consistency,and there is no numerical anomaly in the opening and closing process of the valve groups,which proves the correctness of the derived solution method. The results provide a method for accurately calculating the boundary conditions of complex connected valve groups.