Experimental investigations on characteristics of water-air two-phase flows during water-fillings in undulation pipelines

作     者：Xue-lin Tang Zong-ku Liu Ling Zhang Xiao-qin Li 

作者机构：College of Water Resources and Civil EngineeringChina Agricultural UniversityBeijing100083China Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network SystemChina Agricultural UniversityBeijing100083China Mingyang Smart Energy Group LimitedZhongshan528400China 

出 版 物：《Journal of Hydrodynamics》 (水动力学研究与进展B辑（英文版）)

年 卷 期：2024年第36卷第4期

页      面：706-724页

核心收录：

学科分类：080103[工学-流体力学] 08[工学] 080104[工学-工程力学] 081502[工学-水力学及河流动力学] 0815[工学-水利工程] 0801[工学-力学（可授工学、理学学位）] 

基　　金：Project supported by the National Natural Science Foundation of China(Grant Nos.52079140 51779257) 

主　　题：Water-filling duration trapped air pockets water-air two-phase flow transient flow flow-pattern evolution multi-undulation pipelines 

摘      要：Visual and pressurized pipeline systems with single- and multi-undulation layouts were used to study experimentally and analyze theoretically the transient characteristics of water-air two-phase flow during water fillings in undulation pipelines based on the combination action analyses of both the communicating pipe and the gravity of the water-air two-phase flows in the descending pipe. For the single undulation pipeline, the complex two-phase flow-pattern evolutions including full pipe flow and stratified flow for low, medium, high water-filling velocity cases, respectively, lead to a great difference in transient pressure, flow pattern and the water-filling duration. Especially for low and medium water-filling velocity cases, the hydraulic theories related to hydraulic drop and hydraulic jump were employed to investigate the entrapped air pocket evolutions in the descending pipe, and the mechanism of negative pressure at the top of the undulation pipes was analyzed. For the same multi-undulation pipeline, due to the different elevations of the three undulation points along flow direction, namely three different types of pipeline layout, high-medium-low case (high elevation undulation point, medium one, and low one), low-medium-high and high-low-medium ones, their water-filling durations are significantly different, i.e., approximately 80.02 s, 227.34 s and 617.78 s. Meanwhile, there are significant differences in flow patterns in water filling, namely larger entrapped air pockets in three descending pipes for the high-medium-low case, entrapped air pockets in the first two descending pipes and open channel stratified flow in the last one for low-medium-high case, some bubbles in three descending pipes for the high-low-medium case.