Analysis of Pressure Transient Following Rapid Filling of a Vented Horizontal Pipe
Analysis of Pressure Transient Following Rapid Filling of a Vented Horizontal Pipe
复制标题
DOI：
10.3390/w10111698
复制
发表时间：
2018-11
期刊：
影响因子：
3.4
通讯作者：
Lin Li;D. Zhu;B. Huang
中科院分区：
文献类型：
--
作者：
Lin Li;D. Zhu;B. Huang
在供水和下水道系统中，通常会遇到管道的快速填充/排空，在此期间，压力瞬变可能会导致意外的大压力和/或间歇泉事件。在本研究中，首先开发了一个线性化的分析模型，以获得最大压力的近似解和压力振荡的特性所造成的水平管道中的滞留空气加压时，没有或微不足道的空气释放。压力模式是典型的周期波，类似于正弦运动。驱动压力和初始气穴长度对振荡周期和压力达到峰值的时间有显著影响。当有空气通过通风孔释放时，还使用ANSYS Fluent通过三维计算流体动力学模型进行分析，以提供空气-水相互作用的见解和细节。研究了与加压和空气释放相关的流动特征，并提出了一维模型无法预测的空气-水界面变形。模拟结果表明，系统中的残余空气取决于排气孔的相对位置。压力振荡模式主要有两种：长周期或短周期振荡和水击。当排气孔位于空气被截留的管道端部附近时，可以观察到后者。
Rapid filling/emptying of pipes is commonly encountered in water supply and sewer systems, during which pressure transients may cause unexpected large pressure and/or geyser events. In the present study, a linearized analytical model is first developed to obtain the approximate solutions of the maximum pressure and the characteristics of pressure oscillations caused by the pressurization of trapped air in a horizontal pipe when there is no or insignificant air release. The pressure pattern is a typical periodic wave, analogous to sinusoidal motion. The oscillation period and the time when the pressure attains the peak value are significantly influenced by the driving pressure and the initial length of the entrapped air pocket. When there is air release through a venting orifice, analysis by a three-dimensional computational fluid dynamics model using ANSYS Fluent was also conducted to furnish insights and details of air–water interactions. Flow features associated with the pressurization and air release were examined, and an air–water interface deformation that one-dimensional models are incapable of predicating was presented. Modelling results indicate that the residual air in the system depends on the relative position of the venting orifice. There are mainly two types of pressure oscillation patterns: namely, long or short-period oscillations and waterhammer. The latter can be observed when the venting orifice is located near the end of the pipe where the air is trapped.