Silvia Meniconi

Pressure-reducing valves (PRVs) play a key role in water distribution networks (WDNs), where they are employed to regulate pressure levels and mitigate leakage. The present work describes an experimental study designed to investigate the transient response of a PRV installed at the inlet of a laboratory-scale district metered area (DMA). The closure of a downstream valve along a service line reproduces a typical end-user action and generates a pressure surge propagating through the system. Two distinct operating scenarios were examined, and the analysis of the measured pressure signals offers a basis for discussing the effect of hydraulic transients on the network.

The ongoing evolution of hydraulic modelling software has expanded its application to increasingly complex scenarios, including unsteady-state situations. This study investigates the modelling of a portion of the Water Distribution System in the city of Trieste executed by using a commercial software. The results highlight the software’s ability to capture the dynamic behaviour of the system and provide insights for optimizing pressure control.

This paper presents a comprehensive analysis of energy optimization strategies for the Ferrarin and Arzergrande water pumping stations, located in the Piovese Area, close to Padua, managed by multiutility company AcegasApsAmga S.p.A. Based on studies conducted by the University of Naples Federico II, the paper compares current operational configurations and proposes innovative solutions to reduce energy consumption, improve hydraulic efficiency, and enhance operational flexibility. The integration of high-efficiency pumps, strategic network interconnections, and the use of hydraulic turbines are evaluated for their impact on energy savings and system resilience.

Pressure transients generated by user activity are a potential, yet understudied, cause of failure in plumbing systems (PSs) and service lines (SLs). This study contributes to filling the knowledge gap by conducting a laboratory investigation at the Water Engineering Laboratory of the University of Perugia (Italy). In detail, a full-scale PS supplied by a representative portion of water distribution network was realized and instrumented with high-frequency pressure sensors and an electromagnetic flowmeter. Experimental data were collected by simulating demand variations at four distinct locations within the PS to replicate the activation of domestic devices. The resulting dataset provided valuable in-sights into the effective management of such systems and the development of appropriate protection measures.

Partial blockages in pressurised pipe systems present significant challenges for precise detection, characterisation, and ongoing monitoring. Transient test-based techniques, which utilise sharp but small pressure waves, have shown considerable potential due to their safety and diagnostic capabilities. This paper investigates the transient response of an extended partial blockage—an evolution of a discrete partial blockage that protrudes longitudinally—an increasingly complex condition which has a greater impact on the behavior of pipe systems. Through Computational Fluid Dynamics simulations, the interaction of pressure waves with extended partial blockages of different severity and lengths is examined to assess the resulting pressure response. The results confirm that the pressure signature, generated by extended partial blockages, differs markedly from those of discrete partial blockages. In particular, the magnitudes of the first and second pressure peaks enable accurate characterisation of the severity and extent of the extended partial blockage. These results demonstrate that transient test-based techniques can play a significant role in managing water pipe systems, facilitating more targeted maintenance interventions. Broader implementation of these techniques could enable water utilities to reduce energy consumption, maintain water quality with lower chlorine dosing, and prevent the progression of partial blockages to total pipeline blockage.

The pressure signal of a simple system of reservoir—cast-iron pipe—end valve is simulated using a one-dimensional mathematical model solved with the Method Of Characteristics (MOC). Given the elastic behaviour of cast iron, viscoelastic effects are not considered in this work. The analysis focuses on the combined influence of of Fluid-Structure Interaction (FSI) and water- hammer phenomena. The water hammer is caused by the sudden closure of the end valve, while FSI cannot be neglected as the end valve is neither constrained nor anchored to the ground, but is free to move in the axial direction. This motion is taken into account by modelling the end part of the pipe as a piston attached to a spring, allowing axial oscillations to be captured in the simulation.

To reduce leakage in water distribution networks, several strategies have been developed, each addressing different aspects of the problem. Alongside advanced leak detection technologies, pressure control has proven to be one of the most powerful and widely implemented strategies to reduce leakage. In this perspective, a key technology in pressure management is the use of pressure reducing valves (PRVs). This paper presents field measurements showing significant instability (swing) of a PRV installed in a real pressure management area in Trieste (Italy). Such instability is characterized by very frequent and significant pressure variations. The various factors influencing this feature are pointed out, finding the catch of the problem and suggesting effective solutions.

Pump startup and shutdown induce transients in pressurized water distribution networks (WDNs) that can cause significant pressure variations, posing a risk to the system's integrity, and potentially leading to fatigue failures. This paper presents laboratory experiments designed to study pump-induced transients in a full-scale WDN at the Water Engineering Laboratory of the University of Perugia, Italy. The experimental setup includes a network of high-density polyethylene pipelines arranged in two loops, supplied by pumps set in series. Various pump startup and shutdown scenarios were tested, and the resulting transient pressures were acquired at multiple locations in the network. Both short- and long-period analyses of the experimental pressure signals identify the most vulnerable sections of the network as those either closest to the pump station or located in smaller-diameter pipelines, where wave interactions and trapped surges amplify pressure fluctuations. Particularly under low-demand (e.g., nighttime-like) conditions, these transient waves intensify. The findings also reveal how changes in network configuration and boundary conditions can significantly influence transient dissipation rates. The results provide valuable insights for water utility managers, aiding in the identification of critical network portions and the optimization of pump operations to preserve system integrity.

Understanding the interaction between pressure waves and partial blockages in pipe systems is crucial for enhancing noninvasive detection methods based on the execution of transient tests. Although laboratory and one-dimensional numerical models have also provided valuable results from the practical point of view, analyzing the transient response of partial blockages in terms of local flow field characteristics is of great interest. This paper examines the transient response in laminar flow conditions of partial blockages by using a Computational Fluid Dynamics model. In particular, the time history of pressure and local velocity of transient events is examined during the early phase characterized by the first pressure wave reflected by the partial blockage. Laminar conditions are chosen for their minimal risk in real pipe systems as they give rise to small overpressures. The behavior of discrete partial blockages at two locations is analyzed in detail, with a pipe with no blockage scenario as a reference. Simulations of discrete partial blockages with different severity confirm that the reflected pressure wave contains enough information for locating and characterizing partial blockages. The obtained results provide critical insights for the organization of transient tests toward the detection of partial blockages.