摘要
长距离输水管道水力瞬变过程中水体压强达到汽化压强时,将会发生水柱分离现象,水柱弥合将产生异常高压,导致管路振动、变形甚至爆管事故。已有的水柱分离弥合水锤数学模型主要采用特征线法(Method of characteristics,MOC)计算,并且很少考虑动态摩阻引起的能量衰减。为提高水柱分离弥合水锤现象的计算精确度和稳定性,基于有限体积法二阶Godunov格式,建立了考虑动态摩阻的离散气体空穴模型(Discrete gas cavity model,DGCM)。为实现管道边界和内部单元的统一计算,提出虚拟边界的处理方法。将该模型模拟结果与实验数据以及已有的稳态摩阻模型的计算结果进行比较,并对网格数、压力修正系数等参数敏感性进行分析。结果表明,本模型能够准确模拟出纯水锤、水柱分离弥合水锤两种情况下瞬变压力,与实验数据基本一致;考虑动态摩阻的瞬态压力计算值与实验数据更吻合;与MOC相比,当库朗数小于1.0时,有限体积法二阶Godunov模型计算结果更准确、更稳定;尤其是,压力修正系数取值0.9及较密网格时数学模型能更为准确地再现实验结果。
Water column separation occurs when the water pressure increases to vapor pressure during hydraulic transients in long distance water conveyance pipelines.Abnormal high pressure caused by water columns rejoining can lead to pipe vibration,deformation,and even explosion accidents.The existing mathematical models of water column separation and rejoining water hammer are mostly solved by the method of characteristics(MOC),and rarely consider the energy attenuation caused by unsteady friction factors.In order to improve the computational accuracy and stability of water column separation and rejoining,second-order Godunov scheme of finite volume method(FVM)was introduced to solve the discrete gas cavity model(DGCM)with unsteady friction factor.The virtual boundary method was proposed to realize the unified calculation of pipe boundary and internal nodes.The simulation results of the proposed model were compared with the experimental data and the calculated results from the existing steady friction model.The sensitivity of parameters including mesh number and pressure correction coefficient was analyzed.Results show that the proposed model was capable of accurately simulating the transient pressure in the cases of both pure water hammer and water column separation and rejoining water hammer,which was basically identical with the experimental data.The calculated transient pressure considering the unsteady friction factor was more consistent with the experimental data.Compared with MOC,when the Courant number was less than 1.0,the transient pressure calculated from the proposed model was more accurate and stable.In particular,the mathematical model could more accurately reproduce the experimental results when the pressure correction coefficient was 0.9 and finer mesh was used.
作者
周领
王宁
赵越
王欢
黄坤
卢坤铭
ZHOU Ling;WANG Ning;ZHAO Yue;WANG Huan;HUANG Kun;LU Kunming(College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210098,China;Sichuan Water Resources and Hydroelectric Investigation&Design Institute Co.,Ltd.,Chengdu 610031,China;International Center on Small Hydro Power,Hangzhou 310002,China;Standard&Quality Control Research Institute,Ministry of Water Resources,Hangzhou 310002,China;China Three Gorges Construction Engineering Corporation,Chengdu 610041,China)
出处
《哈尔滨工业大学学报》
EI
CAS
CSCD
北大核心
2023年第4期138-144,共7页
Journal of Harbin Institute of Technology
基金
国家自然科学基金(51679066,51839008)
霍英东教育基金会青年教师基金(161068)。
