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About an Important Phenomenon—Water Hammer
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About an Important Phenomenon—Water Hammer

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Hydraulics and Hydrodynamics".

Deadline for manuscript submissions: closed (30 June 2023) | Viewed by 30211

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Dr. Kamil Urbanowicz

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Guest Editor
Department of Mechanical Engineering and Mechatronics, West Pomeranian University of Technology Szczecin, Piastów 19, 70-310 Szczecin, Poland
Interests: water hammer; unsteady pipe flow; transient flow, cavitation; unsteady friction; retarded strain; numerical modelling; analytical solutions
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Helena M. Ramos

E-Mail Website1 Website2
Guest Editor
Department of Civil Engineering, Architecture and Environment, CERIS, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
Interests: hydropower; hydraulic transients; pumped-storage; water and energy nexus; hydrodynamic; renewables integration; water-energy efficiency
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

When flow in pipes under pressure is forced to stop, start or change direction, suddenly, wave propagation associated with the water hammer phenomena takes place. This phenomenon never used to be as popular as it is today. Due to the importance of this issue in regard to practical engineering, the number of works related to this complex topic is systematically increasing from year to year.

From a historical point of view, engineers have contended with water hammer since the invention and use of pipes for transporting liquid from one place to another. Over 2000 years ago, Marcus Vitruvius Pollio had already described the effects of water hammer and cavitation on clay and lead pipelines supplying water to the contemporary water supply systems being built by the Romans. From a mathematical point of view, the description of this phenomenon began with early von Kries, Joukowsky or Allevi works. Joukowsky investigated wave reflections in pipes and the use of air chambers (equalizing tanks and spring-loaded safety valves), and provided a simple formula for a pressure rise (used even today) caused by a fast valve closure.

Today, the discussion of this subject is very extensive. The key issues for water hammer problems may include: single versus multiple phase flow; laminar versus turbulent flow; elastic versus viscoelastic strain behaviour of the pipe material; gaseous versus vaporous cavitation; Newtonian versus non-Newtonian flow; rigid versus flexible pipe walls; and fast (impulsive) versus slow-transient flow. Consideration of the above-mentioned issues should often include selected accompanying phenomena: mechanical energy dissipation due to fluid friction, the occurrence of viscoelastic retarded deformations of the pipe walls due to liquid column separation resulting from cavitation, and fluid–structure interaction.

This Special Issue is dedicated to all problems related to modelling water hammer phenomena, as well to all problems connected with the experimental verification of this specific unsteady type flow. We are open to review your works in which the influences of accompanying phenomena are discussed, as well as those concerning the methods of securing pipe systems against the negative effects of its impact (noise, vibrations, leakages, etc.), and those which just generally broaden our knowledge of water hammer.

Dr. Kamil Urbanowicz
Prof. Dr. Helena M. Ramos
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • water hammer
  • transient flow
  • unsteady friction
  • cavitation
  • column separation
  • retarded strain
  • fluid structure interaction
  • leakage control
  • numerical models
  • hydrotransients modelling
  • valve manoeuvres
  • start-up and shut-down turbomachines

Published Papers (16 papers)

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Editorial

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11 pages, 233 KiB  
Editorial
New Advances in Water Hammer Problems
by Kamil Urbanowicz and Helena Margarida Ramos
Water 2023, 15(22), 4004; https://0-doi-org.brum.beds.ac.uk/10.3390/w15224004 - 17 Nov 2023
Viewed by 1457
Abstract
When the flow within pressurized pipes experiences abrupt stoppages, initiation, or directional alteration, it gives rise to the phenomenon of water hammer, characterized by the propagation of waves [...] Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)

Research

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40 pages, 4286 KiB  
Article
Exploring the Sensitivity of the Transient Response following Power Failure to Air Valve and Pipeline Characteristics
by Elias Tasca, Mohsen Besharat, Helena M. Ramos, Edevar Luvizotto, Jr. and Bryan Karney
Water 2023, 15(19), 3476; https://0-doi-org.brum.beds.ac.uk/10.3390/w15193476 - 02 Oct 2023
Viewed by 1481
Abstract
Air valves are protective devices often used in pressurised water pipelines, ideally admitting air to limit sub-atmospheric pressures and controlling the release of entrapped air. This work summarises a comprehensive sensitivity analysis of the transient behaviour in a rising water pipeline with an [...] Read more.
Air valves are protective devices often used in pressurised water pipelines, ideally admitting air to limit sub-atmospheric pressures and controlling the release of entrapped air. This work summarises a comprehensive sensitivity analysis of the transient behaviour in a rising water pipeline with an air valve following a pump trip. The paper examines the water hammer stages associated with a pump trip, namely, the initial depressurisation, followed by air admission, then air expulsion, and finally the creation of a secondary pressure wave. For each air valve location and specific set of design conditions, the relationship between the transient magnitude and air valve outflow capacity is found to be non-linear, but to roughly follow the shape of a logistic curve having a lower left plateau for attenuated (type 1) behaviour and transitioning through type 2 behaviour to a higher right plateau for water-hammer-dominated (type 3) behaviour. Through an extensive set of simulations covering a wide range of conditions, the study identifies the size of the critical outflow orifices associated with both type 1 and type 3 responses and assesses the influence of the location of the air valve on the transient magnitude and on the timing of air pocket collapse. Furthermore, the paper highlights that a non-slam air valve is capable of effectively mitigating transient magnitudes provided that its design parameters are judiciously chosen and account for both the system’s attributes and the characteristics of the transient event. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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13 pages, 3157 KiB  
Article
Dimensionless Pressure Response Analysis for Water Supply Pipeline Systems with or without Pumping Station
by Sanghyun Kim
Water 2023, 15(16), 2934; https://0-doi-org.brum.beds.ac.uk/10.3390/w15162934 - 14 Aug 2023
Viewed by 791
Abstract
Dimensionless governing equations of unsteady flow and solutions for the pipeline systems having a surge tank were developed. Frequency domain pressure response expressions for two widely used water supply systems were analyzed in dimensionless frequency and time domains. One is the simple reservoir [...] Read more.
Dimensionless governing equations of unsteady flow and solutions for the pipeline systems having a surge tank were developed. Frequency domain pressure response expressions for two widely used water supply systems were analyzed in dimensionless frequency and time domains. One is the simple reservoir pipeline surge tank valve system and the other is the pipeline system with pump and check valve protected by surge tank. Two different dimensionless expressions for the surge tank were developed and the performance of two expressions was compared. The frequency response pattern of impedance at the downstream valve indicated that the system resonance was determined by the lengths of the main pipeline and the connector and the locations of the surge tank and check valve for the protection of the pumping station. The difference between the simple pipeline system and that of a pump with a check valve was expressed in terms of the phase difference in frequency response distribution. The integrated pressure response for the protected pipeline section was evaluated considering the impact of surge protection in the frequency domain. A better understanding of system behavior can be obtained in terms of specific component isolation both in the frequency and time domain pressure responses. The driven responses in the frequency and time domain can be an important basis for optimum design and operation conditions of water supply systems in dimensionless space. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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13 pages, 2812 KiB  
Article
Finite Volume Method for Transient Pipe Flow with an Air Cushion Surge Chamber Considering Unsteady Friction and Experimental Validation
by Yue Liu, Jianwei Lu, Jian Chen, Yong Xia, Daohua Liu, Yinying Hu, Ruilin Feng, Deyou Liu and Ling Zhou
Water 2023, 15(15), 2742; https://0-doi-org.brum.beds.ac.uk/10.3390/w15152742 - 29 Jul 2023
Viewed by 931
Abstract
In various water transmission systems such as long-distance water transfer projects and hydropower stations, accurate simulation of water hammer is extremely important for safe and stable operation and the realization of intelligent operations. Previous water hammer calculations usually consider only steady-state friction, underestimating [...] Read more.
In various water transmission systems such as long-distance water transfer projects and hydropower stations, accurate simulation of water hammer is extremely important for safe and stable operation and the realization of intelligent operations. Previous water hammer calculations usually consider only steady-state friction, underestimating the decay of transient pressure. A second-order Finite Volume Method (FVM) considering the effect of unsteady friction factor is developed to simulate the water hammer and the dynamic behavior of air cushion surge chamber in a water pipeline system, while an experimental pipe system is conducted to validate the proposed numerical model. Two unsteady friction models, Brunone and TVB models, were incorporated into the water hammer equations, which are solved by the MUSCL–Hancock method. One virtual boundary method was proposed to realize the FVM simulation of Air Cushion Surge Chamber. Comparisons with water hammer experimental results show that, while the steady friction model only accurately predicts the first pressure peak, it seriously underestimates pressure attenuation in later stages. Incorporating an unsteady friction factor can better predict the entire pressure attenuation process; in particular, the TVB unsteady friction model more accurately reproduces the pressure peaks and the whole pressure oscillation periods. For water pipeline systems with an air cushion surge chamber, energy attenuation of the elastic pipe water hammer is primarily due to pipe friction and the air cushion. The experimental results with the air cushion surge chamber demonstrate that the proposed FVM model with the TVB unsteady friction model and the air chamber polytropic exponent near 1.0 can well reproduce the experimental pressure oscillations. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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13 pages, 3376 KiB  
Article
Gas Release and Solution as Possible Mechanism of Oscillation Damping in Water Hammer Flow
by Giuseppe Pezzinga
Water 2023, 15(10), 1942; https://0-doi-org.brum.beds.ac.uk/10.3390/w15101942 - 20 May 2023
Viewed by 985
Abstract
Water hammer flow is examined, putting into evidence that unsteady friction cannot be fully responsible for observed oscillation damping. The measured piezometric head oscillations of water hammer flow experimental tests carried out for very long time (about 70 periods) are presented and compared [...] Read more.
Water hammer flow is examined, putting into evidence that unsteady friction cannot be fully responsible for observed oscillation damping. The measured piezometric head oscillations of water hammer flow experimental tests carried out for very long time (about 70 periods) are presented and compared with the numerical results of a quasi-two-dimensional (2D) flow model. The hypothesis is made that the energy dissipation could be partially due to the process of gas release and solution. An equation for the balance of gas mass is taken into account, already successfully used to improve the comparison between numerical and experimental head oscillations for transient gaseous cavitation. The models are based on a particular implementation of the method of characteristics (MOC-Z). The calibration of the empirical parameters of the models is carried out with a micro-genetic algorithm (micro-GA). The better performance of the proposed model is quantified with comparison of the mean absolute errors for three experimental tests at different Reynolds numbers, ranging from 5300 to 15,400. The corresponding ratios between the mean absolute errors of the models with and without gas release range between 47.3% and 17.7%. It is also shown that different turbulence models give very similar results. The results have some relevance in water hammer research, because sometimes dissipation that is not due to unsteady friction is attributed to it. However, the hypothesized mechanism has to be deepened and validated with further studies. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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14 pages, 4977 KiB  
Article
A Comparison of Different Methods for Modelling Water Hammer Valve Closure with CFD
by Mehrdad Kalantar Neyestanaki, Georgiana Dunca, Pontus Jonsson and Michel J. Cervantes
Water 2023, 15(8), 1510; https://0-doi-org.brum.beds.ac.uk/10.3390/w15081510 - 12 Apr 2023
Cited by 4 | Viewed by 2277
Abstract
Water hammer is a transient phenomenon that occurs when a flowing fluid is rapidly decelerated, which can be harmful and damaging to a piping system. Three-dimensional computational fluid dynamics (CFD) with three-dimensional geometry is a common tool for studying water hammer, which is [...] Read more.
Water hammer is a transient phenomenon that occurs when a flowing fluid is rapidly decelerated, which can be harmful and damaging to a piping system. Three-dimensional computational fluid dynamics (CFD) with three-dimensional geometry is a common tool for studying water hammer, which is more accurate than numerical simulation with one-dimension approximation of the geometry. There are different methods with different accuracy and computational costs for valve closure modelling. This paper presents the result of water hammer 3D simulation with three main technics for modelling an axial valve closure: dynamic mesh, sliding mesh, and immersed solid methods. The variation of the differential pressure variation and the wall shear stress are compared with experimental results. Additionally, the 3D effects of the flow after the valve closure and the computational cost are addressed. The sliding mesh method presents the most physical results compared to the other two methods. The immersed solid method predicts a smaller pressure rise which may be the result of using a source term in the momentum equation instead of modelling the valve movement. The dynamic mesh method adds fluctuations to the primary phenomenon. Moreover, the sliding mesh is less expensive than the dynamic mesh method in terms of computational cost (approximately one-third), which was the primary method for axial valve closure modelling in the literature. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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22 pages, 9420 KiB  
Article
New Optimized Equal-Area Mesh Used in Axisymmetric Models for Laminar Transient Flows
by Pedro Leite Ferreira and Dídia Isabel Cameira Covas
Water 2023, 15(7), 1402; https://0-doi-org.brum.beds.ac.uk/10.3390/w15071402 - 04 Apr 2023
Cited by 1 | Viewed by 1169
Abstract
The current paper aims at assessing the effect of the radial mesh on the description of the axial velocity in steady-state and transient conditions and at presenting the results of a new optimized equal-area mesh. For this purpose, a quasi-2D model is implemented [...] Read more.
The current paper aims at assessing the effect of the radial mesh on the description of the axial velocity in steady-state and transient conditions and at presenting the results of a new optimized equal-area mesh. For this purpose, a quasi-2D model is implemented and tested for different mesh configurations and sizes. A new two-region mesh geometry with 40 cylinders is proposed to optimize the description of the wall shear stress immediately after each pressure variation. This mesh is composed of two regions: one with a high-resolution near the pipe wall and the second with a coarser grid in the pipe core. Different configurations of this mesh are analysed for both steady and unsteady conditions. Results are compared with those obtained by a 1D model and with experimental data for laminar flows, discussed in terms of the computation effort and accuracy. The proposed two-region mesh has demonstrated: (i) a reduction in the simulation error by five times when compared with standard meshes for the same computational effort and for the instantaneous valve closure; (ii) an important improvement in accuracy for an experimental S-shape valve maneuver, particularly for meshes with few cylinders; and (iii) a correct description of the transient pressures collected in the experimental tests. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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12 pages, 6220 KiB  
Article
Rapid Filling Analysis with an Entrapped Air Pocket in Water Pipelines Using a 3D CFD Model
by Duban A. Paternina-Verona, Oscar E. Coronado-Hernández, Hector G. Espinoza-Román, Vicente S. Fuertes-Miquel and Helena M. Ramos
Water 2023, 15(5), 834; https://0-doi-org.brum.beds.ac.uk/10.3390/w15050834 - 21 Feb 2023
Cited by 2 | Viewed by 2302
Abstract
A filling operation generates continuous changes over the shape of an air–water interface, which can be captured using a 3D CFD model. This research analyses the influence of different hydro-pneumatic tank pressures and air pocket sizes as initial conditions for studying rapid filling [...] Read more.
A filling operation generates continuous changes over the shape of an air–water interface, which can be captured using a 3D CFD model. This research analyses the influence of different hydro-pneumatic tank pressures and air pocket sizes as initial conditions for studying rapid filling operations in a 7.6 m long PVC pipeline with an irregular profile, using the OpenFOAM software. The analysed scenarios were validated using experimental measurements, where the 3D CFD model was suitable for simulating them. In addition, a mesh sensitivity analysis was performed. Air pocket pressure patterns, water velocity oscillations, and the different shapes of the air–water interface were analysed. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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19 pages, 4592 KiB  
Article
Finite Volume Method for Modeling the Load-Rejection Process of a Hydropower Plant with an Air Cushion Surge Chamber
by Jianwei Lu, Guoying Wu, Ling Zhou and Jinyuan Wu
Water 2023, 15(4), 682; https://0-doi-org.brum.beds.ac.uk/10.3390/w15040682 - 09 Feb 2023
Viewed by 1414
Abstract
The pipe systems of hydropower plants are complex and feature special pipe types and various devices. When the Method of Characteristics (MOC) is used, interpolation or wave velocity adjustment is required, which may introduce calculation errors. The second-order Finite Volume Method (FVM) was [...] Read more.
The pipe systems of hydropower plants are complex and feature special pipe types and various devices. When the Method of Characteristics (MOC) is used, interpolation or wave velocity adjustment is required, which may introduce calculation errors. The second-order Finite Volume Method (FVM) was presented to simulate water hammer and the load-rejection process of a hydropower plant with an air cushion surge chamber, which has rarely been considered before. First, the governing equations were discretized by FVM and the flux was calculated by a Riemann solver. A MINMOD slope limiter was introduced to avoid false oscillation caused by data reconstruction. The virtual boundary strategy was proposed to simply and effectively handle the complicated boundary problems between the pipe and the various devices, and to unify the internal pipeline and boundary calculations. FVM results were compared with MOC results, exact solutions, and measured values, and the sensitivity analysis was conducted. When the Courant number was equal to 1, the results of FVM and MOC were consistent with the exact solution. When the Courant number was less than 1, compared with MOC, the second-order FVM results were more accurate with less numerical dissipation. As the Courant number gradually decreased, the second-order FVM simulations were more stable. For the given numerical accuracy, second-order FVM had higher computational efficiency. The simulations of load rejection showed that compared with the MOC results, the second-order FVM calculations were closer to the measured values. For hydropower plants with complex pipe systems, wave velocity or the Courant number should be adjusted during MOC calculation, resulting in calculation error, and the error value is related to the parameters of the air cushion surge chamber (initial water depth, air cushion height, etc.). The second-order FVM can more accurately, stably, and efficiently simulate the load-rejection process of hydropower plants compared with MOC. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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15 pages, 3696 KiB  
Article
Energy Analysis of a Quasi-Two-Dimensional Friction Model for Simulation of Transient Flows in Viscoelastic Pipes
by Kai Wu, Yujie Feng, Ying Xu, Huan Liang and Guohong Liu
Water 2022, 14(20), 3258; https://0-doi-org.brum.beds.ac.uk/10.3390/w14203258 - 15 Oct 2022
Cited by 2 | Viewed by 1359
Abstract
Quasi-two-dimensional (quasi-2D) friction models have been widely investigated in transient pipe flows. In the case of viscoelastic pipes, however, the effect of different values of the Reynolds number (Re) on pressure fluctuations (which can lead to water hammer) have not been considered in [...] Read more.
Quasi-two-dimensional (quasi-2D) friction models have been widely investigated in transient pipe flows. In the case of viscoelastic pipes, however, the effect of different values of the Reynolds number (Re) on pressure fluctuations (which can lead to water hammer) have not been considered in detail. This study establishes a quasi-2D friction model employing an integral total energy method and investigates the work due to frictional and viscoelastic terms at different Re values. The results show that viscoelastic work (WP) and frictional work (Df) increase with an increase in Re. However, when the initial Re values are high, the Df values are much larger than the WP values. In addition, for Re < 3 × 105, the 1D model underestimated the viscoelastic terms. There was no significant difference between the two models for Re > 3 × 105. In the case of different initial Re values, the two models produced almost the same values for WP. This study provides a theoretical basis for investigating transient flow from the perspective of energy analysis. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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20 pages, 4276 KiB  
Article
Water Hammer Simulation Using Simplified Convolution-Based Unsteady Friction Model
by Kamil Urbanowicz, Anton Bergant, Michał Stosiak, Adam Deptuła, Mykola Karpenko, Michał Kubrak and Apoloniusz Kodura
Water 2022, 14(19), 3151; https://0-doi-org.brum.beds.ac.uk/10.3390/w14193151 - 06 Oct 2022
Cited by 4 | Viewed by 2294
Abstract
Omission of frequency-dependent hydraulic resistance (skin friction) during modelling of the water hammer phenomenon is unacceptable. This resistance plays a major role when the transient liquid flow occurs in rigid-walled pipes (steel, copper, etc.). In the literature, there are at least two different [...] Read more.
Omission of frequency-dependent hydraulic resistance (skin friction) during modelling of the water hammer phenomenon is unacceptable. This resistance plays a major role when the transient liquid flow occurs in rigid-walled pipes (steel, copper, etc.). In the literature, there are at least two different modelling approaches to skin friction. The first group consists of models based on instantaneous changes in local and convective velocity derivatives, and the second group are models based on the convolution integral and full history of the flow. To date, more popular models are those from the first group, but their use requires empirical coefficients. The second group is still undervalued, even if based on good theoretical foundations and does not require any empirical coefficients. This is undoubtedly related to the calculation complexity of the convolution integral. In this work, a new improved effective solution of this integral is further validated, which is characterised with the use of a simplified weighting function consisting of just two exponential terms. This approach speeds the numerical calculations of the basic flow parameters (pressure and velocity) significantly. Presented comparisons of calculations using the new procedure with experimental pressure runs show the usefulness of the proposed solution and prove that it maintains sufficient accuracy. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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18 pages, 3164 KiB  
Article
Water Hammer in Steel–Plastic Pipes Connected in Series
by Michał Kubrak, Apoloniusz Kodura, Agnieszka Malesińska and Kamil Urbanowicz
Water 2022, 14(19), 3107; https://0-doi-org.brum.beds.ac.uk/10.3390/w14193107 - 02 Oct 2022
Cited by 3 | Viewed by 2312
Abstract
This paper experimentally and numerically investigates the water hammer phenomenon in serially connected steel and HDPE pipes with different diameters. The aim of the laboratory tests was to obtain the time history of the pressure head at the downstream end of the pipeline [...] Read more.
This paper experimentally and numerically investigates the water hammer phenomenon in serially connected steel and HDPE pipes with different diameters. The aim of the laboratory tests was to obtain the time history of the pressure head at the downstream end of the pipeline system. Transient tests were conducted on seven different pipeline system configurations. The experimental results show that despite the significantly smaller diameter of the HDPE pipe compared to the steel pipe, introducing an HDPE section makes it possible to suppress the valve-induced pressure surge. By referring to the results of the experimental tests conducted, the comparative numerical calculations were performed using the fixed-grid method of characteristics. To reproduce pressure wave attenuation in a steel pipe, Brunone-Vitkovský instant acceleration-based model of unsteady friction was used. To include the viscoelastic behavior of the HDPE pipe wall, the one-element Kelvin–Voigt model was applied. By calibrating the unsteady friction coefficient and creep parameters, satisfactory agreement between the calculated and observed data was obtained. The calibrated values of parameters for a single experimental test were introduced in a numerical model to simulate the remaining water hammer runs. It was demonstrated that using the same unsteady friction coefficient and creep parameters in slightly different configurations of pipe lengths can be effective. However, this approach fails to reliably reproduce the pressure oscillations in pipeline systems with sections of significantly different lengths. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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15 pages, 5460 KiB  
Article
Hydraulic Transient Simulation of Pipeline-Open Channel Coupling Systems and Its Applications in Hydropower Stations
by Wei Zeng, Chao Wang and Jiandong Yang
Water 2022, 14(18), 2897; https://0-doi-org.brum.beds.ac.uk/10.3390/w14182897 - 16 Sep 2022
Viewed by 2352
Abstract
Hydraulic systems may involve both pipelines and open channels, which challenges the hydraulic transient analysis. In this paper, a method of characteristics (MOC)-finite volume method (FVM) coupling method has been developed with the pipeline modelled using the MOC and the open channel modelled [...] Read more.
Hydraulic systems may involve both pipelines and open channels, which challenges the hydraulic transient analysis. In this paper, a method of characteristics (MOC)-finite volume method (FVM) coupling method has been developed with the pipeline modelled using the MOC and the open channel modelled using the FVM. The coupling boundaries between these two simulation regions are developed based on Riemann invariants. The simulated parameters can be transmitted from the MOC region to the FVM region and in the reverse direction through the coupling boundaries. Validation of the method is conducted on a simple tank-pipe system by comparing the simulated result using 3D computational fluid dynamics (CFD) analysis. The new method is then applied to a prototype hydropower station with a sand basin located between the upstream reservoir and the turbines. The sand basin is modelled as an open channel coupled with the pipes in the system. The transient processes are also simulated by modelling the sand basin as a surge tank. The comparison with the results by the MOC-FVM coupling method shows the new coupling method can provide more reliable and accurate results. This is because the flow velocity in the horizontal direction in the sand basin is considered in the coupling method but neglected when the sand basin is modelled as a surge tank in the MOC. Full article
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23 pages, 7531 KiB  
Article
A Novel Surge Damping Method for Hydraulic Transients with Operating Pump Using an Optimized Valve Control Strategy
by Zheng Cao, Qi Xia, Xijian Guo, Lin Lu and Jianqiang Deng
Water 2022, 14(10), 1576; https://0-doi-org.brum.beds.ac.uk/10.3390/w14101576 - 14 May 2022
Cited by 1 | Viewed by 2165
Abstract
Hydraulic transients may pose a critical threat to process operation due to devastating surge waves. This paper investigates hydraulic surge and damping control associated with pipe flow modeling and valve optimization. A one-dimensional transient model was developed using the modified instantaneous accelerations-based (IAB) [...] Read more.
Hydraulic transients may pose a critical threat to process operation due to devastating surge waves. This paper investigates hydraulic surge and damping control associated with pipe flow modeling and valve optimization. A one-dimensional transient model was developed using the modified instantaneous accelerations-based (IAB) model, considering energy dissipation, referred to as the compression–expansion effect, which was then solved by the Method of Characteristics (MOC). Analogous to solving valve operation by means of the traveling salesman problem (TSP), a novel surge damping strategy was proposed by applying an improved artificial fish swarm algorithm (AFSA). After validating the unsteady model and the optimization algorithm, wave surge damping effectiveness was evaluated on the basis of case studies in different pump running scenarios. The results showed that the proposed nonlinear optimized control method was able to reduce surge amplitude by 9.3% and 11.4% in pipe systems with and without running centrifugal pump, respectively, and was able to achieve a 34% time margin or a maximal 75.2% surge reduction in the case of using an positive displacement pump. The optimized nonlinear valve closure presents different shapes in fast closing and slow closing situations. The strategy proposed in the present study is beneficial for guiding valve real-time control, as well as providing a reference for valve design for the purpose of wave surge protection. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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14 pages, 2013 KiB  
Article
Sensitivity Analysis of Hydraulic Transient Simulations Based on the MOC in the Gravity Flow
by Jinhao Liu, Jianhua Wu, Yusheng Zhang and Xinhao Wu
Water 2021, 13(23), 3464; https://0-doi-org.brum.beds.ac.uk/10.3390/w13233464 - 06 Dec 2021
Cited by 3 | Viewed by 1958
Abstract
The purpose of this study was to evaluate the sensitivity of input parameters to output results when using the method of characteristics (MOC) for hydraulic transient simulations. Based on a gravity flow water delivery project, we selected six main parameters that affect the [...] Read more.
The purpose of this study was to evaluate the sensitivity of input parameters to output results when using the method of characteristics (MOC) for hydraulic transient simulations. Based on a gravity flow water delivery project, we selected six main parameters that affect the hydraulic transient simulation and selected maximum pressure as the output parameter in order to perform a parameter sensitivity analysis. The Morris sensitivity analysis (Morris) and the partial rank correlation coefficient method based on Latin hypercube sampling (LHS-PRCC) were both adopted. The results show that the sensitivity of each parameter is the same except for the friction factor. The flow rate and Young’s modulus are positively correlated with the maximum pressure, whereas the pipe diameter, valve closing time, and wall thickness are negatively correlated. It is discussed that the variability of the friction factor comes from the function of the flow and pressure regulating valve. When other conditions of the gravity flow project remain unchanged, the maximum pressure increases with the increase in the friction factor. The flow rate, pipe diameter, and valve closing time are the key parameters that affect the model. Meanwhile, Morris and LHS-PRCC proved to be effective methods for evaluating parameter sensitivity in hydraulic transient simulations. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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Review

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21 pages, 3738 KiB  
Review
On Sources of Damping in Water-Hammer
by Alan E. Vardy
Water 2023, 15(3), 385; https://0-doi-org.brum.beds.ac.uk/10.3390/w15030385 - 18 Jan 2023
Cited by 4 | Viewed by 2095
Abstract
Various potential causes of damping of pressure waves in water-hammer-like flows are discussed, with special attention being paid to their qualitative influences on measured pressure histories. A particular purpose is to highlight complications encountered when attempting to interpret causes of unexpected behaviour in [...] Read more.
Various potential causes of damping of pressure waves in water-hammer-like flows are discussed, with special attention being paid to their qualitative influences on measured pressure histories. A particular purpose is to highlight complications encountered when attempting to interpret causes of unexpected behaviour in pipe systems. For clarity, each potential cause of damping is considered in isolation even though two or more could exist simultaneously in real systems and could even interact. The main phenomena considered herein are skin friction, visco-elasticity, bubbly flows and porous pipe linings. All of these cause dispersive behaviour that can lead to continual reductions in pressure amplitudes. However, not all are dissipative and, in such cases, the possibility of pressure amplification also exists. A similar issue is discussed in the context of fluid–structure interactions. Consideration is also given to wavefront superpositions that can have a strong influence on pressure histories, especially in relatively short pipes that are commonly necessary in laboratory experiments. For completeness, attention is drawn towards numerical damping in simulations and to a physical phenomenon that has previously been wrongly cited as a cause of significant damping. Full article
(This article belongs to the Special Issue About an Important Phenomenon—Water Hammer)
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