Water Supply Network Flushing Experiment With Barometric Pulse Method And Numerical Simulation

Water supply network is an important component of water supply systems. Purified water goes through the intricate network of underground pipes to users. General water treated by plants can meet the drinking water health standards. But sent to the user through the water supply network, the water has been stayed in the water supply network for a period of time. During this period water will be subjected to the secondary pollution. In pipe networks "growth ring" is an important factor to cause secondary pollution, so clearing the "growth rings" will help improve water quality and the capacity of pipes carrying water. Comparison of several methods of cleaning pipes, barometric pulse flushing is a very good method. Improving the efficiency of flushing of barometric pulse method, it has the important theoretical and practical significance to reduce secondary pollution in water supply network."Growth ring" is a mixture which consists of variety of inorganic matter, organic matter, and microbe. The formation mechanism of the growth ring is complex, not only effects of physically precipitation, pipeline electrochemical corrosion, chemical stability, and biological stability, in terms of the metal pipe, but also corrosion by iron bacteria, sulfate-reducing bacteria. Growth rings affect the water quality, and with the growth of pipe age, thickening and increasing roughness of wall, so increasing pipe resistance coefficient, reducing the cross section area, directly affecting the capacity of the pipeline transmission and head, and increasing energy consumption and leakage consumption.By designed and built the test platform, the pulses pattern of barometric pulse flushing method is studied. The results show that in a condition of the gas pressure and water flow and maintaining the time of filling air, with changes of the time of stopping air, flow velocity and head sharply increase at the beginning, and later steadily rise. When the time of filling air is 5s, the velocity and head reach the maximum. Remaining unchanged time of filling air, with the stopped time growth, the velocity and head increase linearly in the pipes. In a certain value of gas pressure, with the increase of water flow, velocity and head in the pipes are linear relation. In a certain value of the flow, with the increase of gas pressure, velocity and head in the pipes are also linear relation. Study on numerical simulation of two-phase gas-liquid in the experimental pipe. For the experimental pipe sections, grid models of the entrance straight section and the bend section are established respectively. Used separate non-steady solution method, numerical simulation is processed of two-phase gas-liquid in entrance straight section. Display real-time results at 0.0005s,0.0010s,0.0015s, and 0.0020s. The flow pattern of two-phase gas-liquid analyzing, a "slug flow" will be formed in some boundary conditions. The theory of "slug flow" explains the energy conversion process, its tail vortex and the effect of removing "growth rings". Calculate the flow field of bend section with steady-state solver, and analysis pressure and velocity within the pipe. Experiments demonstrate that the elbows of pipes affect to remove "growth rings" at a certain extent.