Hydraulic Transient Guidelines for Protecting Water Distribution Systems

Abstract

Transients can introduce large pressure forces and rapid fluid accelerations into a water distribution system. These disturbances may result in pump and device failures, system fatigue or pipe ruptures, and even the backflow/intrusion of dirty water. Many transient events can lead to water column separation, which can result in catastrophic pipeline failures. Thus, transient events cause health risks and can lead to increased leakage or decreased reliability. Transient flow simulation has become an essential requirement for ensuring safety and the safe operation of drinking water distribution systems. This article provides a basic understanding of the physical phenomena and context of transient conditions, presents practical guidelines for their suppression and control, and compares the formulation and computational performance of widely used hydraulic transient simulation schemes. Such capabilities greatly enhance the ability of water utilities to conceive and evaluate cost-effective and reliable water supply protection and management strategies and safeguard public health.A 112 MAY 2005 | JOURNAL AWWA • 97:5 | PEER-REVIEWED | BOULOS ET AL sient pressures are most important when the rate of flowis changed rapidly, such as resulting from rapid valve closures or pump stoppages. Such disturbances, whether caused by design or accident, may create traveling pressure and velocity waves of large magnitude. These transient pressures are superimposed on the steady-state conditions present in the line at the time the transient pressure occurs. The severity of transient pressures must be determined so that the water mains can be properly designed to withstand these additional loads. In fact, pipes are often characterized by their "pressure ratings" that define their mechanical strength and have a significant influence on their cost.

Optimizing Intermittent Water Supply in Urban Pipe Distribution Networks

“…In each case, the user specification of boundary condition type allows the solver to update the ghost cell values. For example, in the network shown in Figure 2.1(b), a time series of Q or A would be specified at each "inflow" node (cases (2) and (3)). At the labeled "outflow" nodes, the user may choose between several possible descriptions of how a valve allows water to exit the end of a pipe.…”

“…Although the causes of pipe damage are complex and myriad, pressure transients play a role [11,2]. Internal pressure contributes to axial, longitudinal and hoop stress in pipes [26], and pressure transients may help cause both pipe bursts (associated with high-pressure events) and collapses (associated low-pressure events) [39].…”

Análisis del golpe de ariete en un sistema de distribución de agua

“…Más tarde vinieron los aportes de diversos autores en el contexto del MC y/o del Método de la Onda Característica MOC (antes llamada Método de la Onda Plana MOP), donde se mostraban los resultados obtenidos en distintos SDAs, como en Watters (1984); Boulos et al (1990); Karney (1984); Karney y McInnis (1992); Simpson y Wu (1997); Boulos et al (2005); Wood et al (2005); Jung et al (2007Jung et al ( , 2009aJung et al ( , 2009b; Mansour−Rezaei et al (2013); etc. Sin embargo, es bien conocido que el MC posee restricciones numéricas que limitan su ámbito de aplicación, especialmente en lo referido al número de Courant (C n ), cuyo valor debe ser obligatoriamente igual a 1.0 para garantizar la estabilidad y precisión de los resultados.…”

Effect of Friction Source in the Hydraulic Transient in a Pipeline Systemusing Method of Characteristics

“…Later on and due to the combined efforts of many researchers such as Parmakian, (1963( ), Zhang, (2003, Wood (2005), and their refinement to the governing equations of hydraulic transient in closed conduct had resulted in classical mass and momentum equations for one dimensional water hammer flows. Although these classical equations contain all physics necessary to model wave propagation in simple and complex pipe systems (Boulos, 2005), ever since these equations had been analyzed, discussed, re-derived and elucidated in many texts and journals attempting to improve them and getting more efficient results while solving them. Various methods were developed to analyze the hydraulic transient flow problem in pipes among of these the method of charactristic has been used in simulation the pipeline system such as in work of Guo, (2012) and Lee, (2013).…”