The Experimental And Modeling Study On Two-phase Gas-liquid Flow In Long-distance Water Pipe

In the long-distance water system, due to precipitation of dissolved gases andwater through the water pipes at the beginning or repair and other reasons, thepipeline will make the performance of gas-liquid two-phase flow in a common state.Flowing form with a simple two-phase flow compared to the more diverse, thehydraulic transition occurs during the interaction and mutual influence between thetwo phases of the pipeline pressure fluctuations lead to more complex, secure it tothe long-distance water pipeline very unfavorable. Therefore it is necessary tounderstand the flow patterns in specific long-distance water pipelines appear andestablish appropriate based on the hydraulic characteristics of the flow patterntransition process model, the pressure fluctuations in the pipeline to analyze thesituation and prevent the occurrence of tube rupture the pipe for long-distancetransmission safe operation of the water system to provide evidence.So far the study of two-phase flow, there is little for the long-distance waterconveyance system to carry out. In this paper, the long-distance water conveyancesystem test platform to build a series of tests, combined with the classical theory oftwo-phase flow, expand the following research:(1)the volume of water within a certain range and adjusted by way of thehigh-speed camera to obtain different air-water ratio, the ramp up, horizontal,inclined arrangement of three different drop appears in the flow duct type divisiongives more detailed flow pattern map, fitting the conversion relationship betweenthe various flow patterns and analyzes the main factors affecting the flow pattern;against horizontal pipe flow pattern map, with its classic Taitel flow pattern map,Mandhane flow comparative analysis chart type, found the test results agree wellwith both, to verify the accuracy of the obtained test flow pattern map, also showedchanges in the mechanism of long distance pipeline flow is also associated with thesame type.(2) based on the extraction of different flow characteristics of two-phase flowin the pipeline status of simplification and assumptions appropriate to establish thepressure fluctuations in the pipe when the situation homogeneous flow model ofhydraulic transition process to occur. Respective upstream and downstream pipingclear boundary conditions, taking into account due to the presence of gas-phasewater hammer wave velocity values will change the formula for velocity wasmodified to obtain a complete hydraulic calculation model, using a computer to solve its preparation of the corresponding program.(3) control the flow rate at1.0~2.2m/s, the gas in the0~2.0m3/h range ofthe system in different operating conditions, hydraulic transient analysis oftwo-phase flow off valve resulting in water hammer, water hammer gas pressurefluctuations and relationships, as well as the size of the water off valve of time. Themodel calculated and measured values of water hammer pressure comparison, thesame trend both calculated and measured values of the maximum water hammerpressure relative deviation of less than3%, the results show that for the test device,the model is applicable.