Numerical study of the blockage length effect on the transient wave in pipe flows

Abstract

A pipeline with an extended blockage is modelled as a system of three pipes in series. A computational fluid dynamics approach using the ADINA software is adapted to solve the slightly compressible turbulent flow problem with complex geometry. Two-dimensional axisymmetric computational results are validated by several examples. In practice, the water hammer wave generated by rapid valve closure usually exhibits wave front smearing. The numerical analysis shows that for a blockage length larger than the wave front thickness, the magnitude of the incident wave may be significantly suppressed as a result of the interaction between the blockage and the wave front. By reflecting negative pressure waves toward the incident wave before its maximum pressure arrives at the blockage, the maximum transient pressure may be considerably reduced. Consequently, the blockage behaves as a discrete blockage. However, if the blockage length is large compared with the thickness of the wave front, the incident wave conserves its initial amplitude, and the blockage behaves as an extended blockage. Therefore, the occurrences of discrete and extended blockages depend on the thickness of the wave front and thus on the rapidity of the maneuver that generates the transient.

Cramer-Rao Lower Bound for Performance Analysis of Leak Detection

“…In addition, the CRLB shows that the larger the value of J (number of measured frequencies), the smaller the variance of the leak estimate. This dependence on frequency provides a theoretical support for the intuitive result that sharper transients (wider frequency bandwidth) result in more reliable (accurate) defect detection and agrees with the results found by Lee et al (2013Lee et al ( , 2015, Zhao et al (2018), Louati et al (2017), and Wang and Ghidaoui (2018b).…”

“…These errors mean that TBDDM results need to be interpreted using a statistical framework (Duan 2016;Sattar and El-Beltagy 2017). This approach for TBDDM is in its infancy, but is beginning to bear fruit (e.g., Vitkovsky et al 2007;Lee et al 2015;Wang and Ghidaoui 2018b;Zhao et al 2018).…”

Fluid-Structure Interaction in Transient-Based Extended Defect Detection of Pipe Walls

“…The latter is known as Inverse Transient Analysis (ITA) (Covas and Ramos 2010). The extended deteriorations of the pipe wall detected by TBRA in both time and frequency domains include blockages Duan et al 2013Duan et al , 2014Louati et al 2017Louati et al , 2018Zhao et al 2018;Keramat and Zanganeh 2019) and corrosions (Stephens et al 2013;Gong et al 2013Gong et al , 2015aGong et al , b, 2018. A combination of these deteriorations was investigated by Gong et al (2014).…”

Modeling of transient flows in viscoelastic pipe network with partial blockage

“…As one of the many problems faced in piping systems, leakage and blockage can be caused by different physical and chemical processes in pipelines and pipe networks, ultimately resulting in failure, energy loss, and reduced system efficiency. Transient flow and its application as a method of assessing the effects of leakage and blockage in piping systems can be found in Stephens et al (2002), Adewumi et al (2003), Haghighi & Ramos (2012), Meniconi et al (2012), Tuck et al (2013), Duan (2016Duan ( , 2018Duan ( , 2020, Duan et al (2014Duan et al ( , 2017a, Capponi et al (2017Capponi et al ( , 2020, Zhao et al (2018), Louati et al (2018), Rahmanshahi et al (2018), Keramat & Zanganeh (2019), Zouari et al (2020), Zhang et al (2020), andPan et al (2021). Stephens et al (2002) conducted field investigations and used transient flows to identify the blockages in a long pipeline as part of a piping system composed of pipelines, branches, and loops.…”