摘要
为了研究输水管道窝气对管路水力损失的影响,对1套包含小坡度长下坡段的管路系统分别在自然重力进流、低虹吸进流、高虹吸进流(虹吸进口装有整流装置)条件下进行管道满流与带气试验测量.创新建立窝气阻力系数β定量表示窝气阻力造成的水力损失增加,提出了整个管路窝气阻力系数的计算公式.基于试验数据分析了不同进流方式在带气与不带气条件下的管路阻力特性,并验证了窝气形成气阻机理的存在.研究结果表明:输水管道窝气会减小管道有效过流面积,造成管路水力损失显著增加,且管道的高低起伏越多,管路中弯头、变径管件数量越多,管道窝气阻力系数β越大;虹吸式进流在整流装置的作用下,较自然重力式进流会降低管道摩擦系数,并且高虹吸下的水力摩擦系数最小;通过合理设计,虹吸整流装置的多孔结构可以根据管道流量的大小不断自动调节其自身的阻力和开度,有效控制管道入口进气.
To explore the influence of entrapped air in a water pipeline on its hydraulic loss,a small slope siphon test rig,which is an undulating pipe with a long downward sloping pipeline,was built.Experiments were carried out under different inlet conditions,namely natural inlet,low siphon inlet and high siphon inlet(with a multi-hole siphon head).At first,an entrapped air resistance factorβwas innovatively introduced to account for the increase of hydraulic loss due to the entrapped air in a pipe,and the formulas for determining the flow resistance in the pipe were deduced.Then,the flow resistance characteristics of the pipe were analyzed based on the experimental data obtained under diffe-rent inlet conditions with and without entrapped air.The mechanism for entrapped air to increase flow resistance was verified.The results show that the entrapped air can reduce the effective flow cross-sectional area and increase the hydraulic loss in the water pipeline considerably,and the more the numbers of undulations and pipe fittings in the pipeline,the larger the entrapped air resistance factorβ.Compared with natural inlet,a siphon inlet can reduce the hydraulic friction factor of the pipeline,and the hydraulic friction factor is the smallest for the high siphon inlet.If a multi-hole siphon head is designed properly,the multi-hole structure can automatically adjust its own resistance and opening according to the flow rate in the pipeline,then can effectively control the air flow rate at the pipeline inlet,eventually,reduces the hydraulic loss in the pipeline.
作者
张金凤
蔡海坤
方玉建
陈圣波
徐捷
李亚林
ZHANG Jinfeng;CAI Haikun;FANG Yujian;CHEN Shengbo;XU Jie;LI Yalin(National Research Center of Pumps,Jiangsu University,Zhenjiang,Jiangsu 212013,China)
出处
《排灌机械工程学报》
EI
CSCD
北大核心
2020年第11期1125-1130,1188,共7页
Journal of Drainage and Irrigation Machinery Engineering
基金
国家重点研发计划项目(2018YFB0606101)
国家自然科学基金资助项目(51809120)
江苏省自然科学基金资助项目(BK20180871)
中国博士后科学基金资助项目(2018M640462)
江苏省高等学校自然科学研究项目(18KJB4701005)。
关键词
窝气阻力
整流装置
虹吸
输水管道
水力损失
entrapped air resistance
inlet condition
siphon head
water pipelines
hydraulic loss
作者简介
第一作者/通信作者:张金凤(1981—),女,内蒙古赤峰人,研究员(zhangjinfeng@ujs.edu.cn),主要从事流体机械理论与设计及流动分析研究;第二作者:蔡海坤(1994—),男,江苏盐城人,硕士研究生(chkqfyys@sina.com),主要从事流体机械优化设计研究。
