Study on impedance size optimization of a one-way surge tank in a long-distance water supply system

The size of the impedance hole of the one-way surge tank will affect its protection against water hammer. In this paper, a mathematical model of one-way surge tank with impedance is established based on the characteristic line method. The pressure-reducing penetration formula of the one-way surge tank including impedance loss and the calculation formula of make-up water flow are deduced. Based on these formulas, the influence of impedance hole diameter ratio (ratio of impedance hole of one-way surge tank to diameter of water pipeline) on the water hammer protection effect is analyzed, and the reasonable value range of impedance hole diameter ratio is given. The correctness of the theoretical analysis results is verified by an engineering example. The results show that the pressure and flow relationship derived from the formula are consistent with the numerical simulation results. The penetration pressure drop of the one-way surge tank is inversely proportional to the impedance size. When the impedance hole diameter ratio is less than 0.2, the penetration pressure drop will cause serious negative pressure. The make-up water flow is proportional to the size of the impedance hole, and the make-up water volume should be reduced while ensuring that the pipeline has no negative pressure. HIGHLIGHTS The mathematical model of impedance type one-way tower is established.; The relationship between the penetration pressure drop of the tower and the size of the impedance hole is deduced.; The relationship between the filling water flow rate of the tower and the size of the impedance hole is deduced.; The reasonable value range of impedance hole size of the tower is given.