城市供热、供水等有压管道系统在事故工况下极易发生水锤，并可能引发破坏性极强的液柱分离与弥合水锤，严重威胁系统安全。基于传统的弹性管道模型，对于高密度聚乙烯（HDPE）等粘弹性管道的数值计算偏差较大。此外，水温和流速等运行参数的变化进一步加大了流固耦合作用机制的复杂性。因此本文通过实验、数值计算与理论分析相结合的方法，搭建首端快关阀激励的液柱分离与弥合水锤的泵-阀门-水箱实验台系统，研究了不同水温（20℃~40℃）与流速（1.68m/s~2.83m/s）对粘弹性管道液柱分离水锤压力波动的影响。首先基于离散蒸汽空腔模型（DVCM）和粘弹性管道本构模型，建立粘弹性管道液柱分离水锤模型，其次基于整体能量分析方法，研究不同水温与流速对粘弹性管道液柱分离水锤的能量转化机制的影响。研究结果表明，初始流速增大导致空腔溃灭以后第一压力峰值非线性上升，水温升高则使压力峰值呈线性下降。空腔持续时间随着水温升高缩短比例增大。对于整个管道的能量耗散，在空腔存在阶段以摩阻耗散为主，且随初始流速的增大而增强；空腔溃灭后的纯液相阶段，粘弹性耗散占主导，不同流速下的机械能衰减趋势一致。水温升高使得空腔存在阶段的能量耗散减小，空腔溃灭后的能量耗散增强，整体能量转化比例减小。该研究为此类管道的安全设计、风险防控与运行优化提供了关键理论依据。

Pressurized pipeline systems used in urban heating and water supply are susceptible to water hammer under emergency operating conditions, which may trigger highly destructive liquid column separation and and subsequent cavity-collapse-induced water hammer, thereby posing a serious threat to system safety. For viscoelastic pipelines such as high-density polyethylene (HDPE) pipes, traditional elastic-pipe models often produce considerable deviations in numerical prediction. In addition, variations in operating parameters, such as water temperature and flow velocity, further complicate the fluid-structure interaction mechanisms. Therefore, this study combines experiments, numerical simulations, and theoretical analysis to establish a pump-valve-tank experimental system for investigating liquid column separation and cavity-collapse water hammer in viscoelastic pipes induced by rapid closure of an end valve. The effects of different water temperatures (20-40 °C) and flow velocities (1.68-2.83 m/s) on pressure fluctuations are systematically examined.Firstly, a viscoelastic-pipe model for liquid column separation water hammer is developed based on the discrete vapor cavity model (DVCM) and viscoelastic constitutive equations. Secondly, using an overall energy analysis method, the effects of water temperature and flow velocity on the energy conversion mechanisms during liquid column separation in viscoelastic pipes are investigated. The results show that, with increasing initial flow velocity, the first pressure peak after cavity collapse increases nonlinearly, whereas it decreases linearly with increasing water temperature. In addition, the duration of cavity existence decreases approximately linearly as water temperature rises. During the cavity-presence stage, frictional dissipation dominates the energy loss throughout the pipeline and increases with initial flow velocity. In contrast, during the pure liquid phase after cavity collapse, viscoelastic dissipation becomes dominant, while the trend of mechanical energy attenuation remains similar under different flow conditions. As water temperature increases, energy loss during the cavity-presence stage decreases, whereas energy loss after cavity collapse intensifies, resulting in a lower overall energy conversion ratio. These findings provide an important theoretical basis for the safe design, risk prevention, and operational optimization of viscoelastic pipeline systems.