A four-equation friction model for water hammer calculation in quasi-rigid pipelines

2017 ◽  
Vol 151 ◽  
pp. 54-62 ◽  
Author(s):  
Abdelaziz Ghodhbani ◽  
Ezzeddine Haj Taïeb
Keyword(s):  
Water Hammer ◽  
Friction Model

Fast Meshless Solution With Lumped Friction for Water Hammer

2020 ◽  
Author(s):  
Yuanzhi Xu ◽  
Zongxia Jiao ◽  
Longfei Zhao
Keyword(s):  
Computational Grid ◽  
Water Hammer ◽  
Friction Model ◽  
Time Cost ◽  
Improved Method ◽  
Fluid Friction ◽  
Time Line ◽  
Practical Applications ◽  
Distributed Friction ◽  
Mesh Grid

Abstract The water hammer in pipelines, with the absence of fluid friction, could be solved by a time-domain exact solution, using a simple recursive process. No computational grid was needed, but the calculation time cost was extremely high. Its improved method, named as the fast meshless solution (FMS), was developed to speed the computation by introducing the time-line interpolation. For the purpose of practical applications, the attempt to consider fluid friction in the FMS is presented here. As there is no mesh grid in the distance-time plane, the distributed friction model can not be employed upon the presented method directly. The fluid friction lumped at the pipe end is proposed, and both steady and unsteady friction are studied. A benchmark problem of the water hammer in a reservoir-pipe-valve (RPV) system is employed for the validation and comparison. The water hammer considering lumped friction can be calculated fast by the FMS, and the accuracy is acceptable. The method discussed here may be of interest in a quick assessment of the piping water hammer.

scholarly journals Approximate approach for improving pressure attenuation accuracy during hydraulic transients

2021 ◽  
Author(s):  
Chao Yu ◽  
Xiaodong Yu ◽  
Lei Zhang ◽  
Bhusan Neupane ◽  
Jian Zhang
Keyword(s):  
Reynolds Number ◽  
Water Hammer ◽  
Friction Model ◽  
Pipe Network ◽  
Network Systems ◽  
Initial Flow ◽  
Friction Term ◽  
Smooth Pipe ◽  
The Relationship ◽  
Good Agreement

Abstract The quasi-steady friction model is generally adopted in water hammer simulation in pipe network systems, which cannot accurately reflect the attenuation of pressure, while the existing unsteady friction model is challenging to use in complex pipe network systems. In this study, a convenient method for treating the friction term is proposed based on the Moody diagram. The attenuation process of water hammer pressure can be accurately reflected by reading the relationship curve between Reynolds number and the Darcy friction factor in the pipeline transient process. Combined with the classical water hammer experiment and the long pipe valve closing experiment in our laboratory, the accuracy of this model is verified, and the influence of absolute roughness (e) and Reynolds number (Re) on the model was analyzed as well. The results show that the pressure attenuation using the Method of Characteristics (MOC) and the proposed friction model has a good agreement with the experimental data. The absolute roughness has little influence on the results in hydraulically smooth pipe, while the minimum Reynolds number has a significant influence. When selecting the minimum Reynolds number, 2% ∼ 5% of the initial flow rate is recommended for calculation.

scholarly journals Analysis of Unsteady Friction Models Used in Engineering Software for Water Hammer Analysis: Implementation Case in WANDA

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 495
Author(s):  
Omar M. Abdeldayem ◽  
David Ferràs ◽  
Sam van der Zwan ◽  
Maria Kennedy
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Water Hammer ◽  
Friction Model ◽  
Engineering Practice ◽  
Engineering Software ◽  
Viscoelastic Effects ◽  
Classic Approach ◽  
Friction Models ◽  
Physical Phenomena

Transient events are frequent in water distribution systems. However, until now, most of the applications based on transient analyses are merely theoretical. Additionally, their implementation to real engineering problems is limited due to several physical phenomena accompanying transient waves, which are not accounted for in the classic approach, such as unsteady friction. This study investigates different unsteady friction models’ performance in terms of accuracy, efficiency, and reliability to determine the most-suited engineering practice. As a result of this comparison, Vítkovský’s unsteady friction model was found to be the best fit and was then implemented in WANDA commercial software. The implementation was verified with experimental data based on a reservoir–pipe–valve system. The model proved excellent performance; however, it was noticed that it fell short in simulating plastic pipes, where viscoelastic effects dominate. The upgraded software was then tested on different hydraulic networks with varying pipe materials and configurations. The model provided significant improvement to water hammer simulations with respect to wave shape, damping, and timing.

Experimental Evaluation of Ability of Relap5, Drako®, Flowmaster2™ and Program Using Unsteady Wall Friction Model to Calculate Water Hammer Loadings on Pipelines

2006 ◽  
Author(s):  
Jerzy Marcinkiewicz ◽  
Adam Adamkowski ◽  
Mariusz Lewandowski
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Transient Flow ◽  
Water Hammer ◽  
Friction Model ◽  
Third Party ◽  
Wall Friction ◽  
Courant Number ◽  
Common Procedure ◽  
Friction Models

Mechanical loadings on pipe systems caused by water hammer (hydraulic transients) belong to the most important and most difficult to calculate design loadings in nuclear power plants. The most common procedure in Sweden is to calculate the water hammer loadings on pipe segments, according to the classical 1D theory of liquid transient flow in a pipeline, and then transfer the results to strength analyses of pipeline structure. This procedure assumes that there is quasi-steady respond of the pipeline structure to pressure surges — no dynamic interaction between the fluid and the pipeline construction. The hydraulic loadings are calculated with 1-D so-called “network” programs. Commonly used in Sweden are Relap5, Drako and Flowmaster2 — all using quasi-steady wall friction model. As a third party accredited inspection body INSPECTA NUCLEAR AB reviews calculations of water hammer loadings. The presented work shall be seen as an attempt to illustrate ability of Relap5, Flowmaster2 and Drako programs to calculate the water hammer loadings. A special attention was paid to using of Relap5 for calculation of water hammer pressure surges and forces (including some aspects of influence of Courant number on the calculation results) and also the importance of considering the dynamic (or unsteady) friction models. The calculations are compared with experimental results. The experiments have been conducted at a test rig designed and constructed at the Szewalski Institute of Fluid–Flow Machinery of the Polish Academy of Sciences (IMP PAN) in Gdansk, Poland. The analyses show quite small differences between pressures and forces calculated with Relap5, Flowmaster2 and Drako (the differences regard mainly damping of pressure waves). The comparison of calculated and measured pressures and also a force acting on a pre-defined pipe segment show significant differences. It is shown that the differences can be reduced by using unsteady friction models in calculations. Recently, such models have been subjects of works of several researches in the world.

scholarly journals Efficient approach toward the application of the Godunov method to hydraulic transients

2020 ◽  
Vol 22 (5) ◽  
pp. 1370-1390 ◽  
Author(s):  
Susovan Pal ◽  
Prashanth Reddy Hanmaiahgari ◽  
Martin F. Lambert
Keyword(s):  
Finite Volume ◽  
Water Hammer ◽  
Friction Model ◽  
Second Order ◽  
Godunov Method ◽  
Computational Time ◽  
Godunov Scheme ◽  
Riemann Solvers ◽  
First Order ◽  
Volume Method

Abstract The proposed study investigated the applicability of the finite volume method (FVM) based on the Godunov scheme to transient water hammer with shock front simulation, in which intermediate fluxes were computed using either first-order or second-order Riemann solvers. Finite volume (FV) schemes are known to conserve mass and momentum and produce the efficient and accurate realization of shock waves. The second-order solution of the Godunov scheme requires an efficient slope or a flux limiter for error minimization and time optimization. The study examined a range of limiters and found that the MINMOD limiter is the best for modeling water hammer in terms of computational time and accuracy. The first- and second-order FVMs were compared with the method of characteristics (MOCs) and experimental water hammer measurements available in the literature. Both the FV methods accurately predicted the numerical and experimental results. Parallelization of the second-order FVM reduced the computational time similar to that of first-order. Thus, the study presented a faster and more accurate FVM which is comparable to that of MOC in terms of computational time and precision, therefore it is a good substitute for the MOC. The proposed study also investigated the implementation of a more complex convolution-based unsteady friction model in the FVM to capture real pressure dissipation. The comparison with experimental data proved that the first-order FV scheme with the convolution integral method is highly accurate for computing unsteady friction for sudden valve closures.

Pressure transients in a Canadian sewage force main

2004 ◽  
Vol 31 (6) ◽  
pp. 1039-1050 ◽  
Author(s):  
David H Axworthy ◽  
Normand Chabot
Keyword(s):  
Pressure Head ◽  
Field Testing ◽  
Water Hammer ◽  
Friction Model ◽  
Data Logging ◽  
Relief Valve ◽  
Protection Measures ◽  
Pump Station ◽  
Before And After ◽  
Surge Protection

Severe water hammer following pump shutdown was suspected to be the cause of pipe displacement at a pump station in Saguenay, Quebec, because it appeared that insufficient surge protection was installed on the force main. To confirm this assertion and prevent further pipe displacement, data logging of a field test of the sewage pump station undergoing power failure was conducted in combination with the development of a water-hammer computer model for the design of additional surge protection measures. This paper describes the results of field testing, both before and after the installation of additional surge protection, and the calibration of a method of characteristics water-hammer model that accounts for vaporous cavitation and unsteady friction effects within the force main. Good agreement is shown between measured and computed pressure head histories at the pump station and at a vacuum relief valve following loss of power to a pump. To the authors' knowledge, this paper presents one of the first applications of the unsteady friction model referenced in this paper to a real system.Key words: sewage, force main, pump, water hammer, unsteady friction, data logging.

An Experimental Study to Predict Dynamic Performance of Check Valve by Water Hammer

2019 ◽  
Vol 19 (1) ◽  
pp. 1-12
Author(s):  
Tae-Kook Park ◽  
Yong-Bum Lee ◽  
Jae-Hyeong Kim ◽  
Ki-Chun Lee ◽  
Dong-Cheon Baek
Keyword(s):  
Experimental Study ◽  
Dynamic Performance ◽  
Check Valve ◽  
Water Hammer

Rubber–Road Contact: Comparison of Physics-Based Theory and Indoor Experiments

2016 ◽  
Vol 44 (3) ◽  
pp. 150-173 ◽  
Author(s):  
Mehran Motamedi ◽  
Saied Taheri ◽  
Corina Sandu
Keyword(s):  
Rough Surface ◽  
Practical Importance ◽  
Surface Profile ◽  
Surface Characteristics ◽  
Mechanical Analysis ◽  
Friction Model ◽  
Rubber Friction ◽  
Optical Profilometer ◽  
Viscoelastic Modulus ◽  
Longitudinal Slip

ABSTRACT For tire designers, rubber friction is a topic of pronounced practical importance. Thus, development of a rubber–road contact model is of great interest. In this research, to predict the effectiveness of the tread compound in a tire as it interacts with the pavement, the physics-based multiscale rubber-friction theories developed by B. Persson and M. Klüppel were studied. The strengths of each method were identified and incorporated into a consolidated model that is more comprehensive and proficient than any single, existing, physics-based approach. In the present work, the friction coefficient was estimated for a summer tire tread compound sliding on sandpaper. The inputs to the model were the fractal properties of the rough surface and the dynamic viscoelastic modulus of rubber. The sandpaper-surface profile was measured accurately using an optical profilometer. Two-dimensional parameterization was performed using one-dimensional profile measurements. The tire tread compound was characterized via dynamic mechanical analysis. To validate the friction model, a laboratory-based, rubber-friction test that could measure the friction between a rubber sample and any arbitrary rough surface was designed and built. The apparatus consisted of a turntable, which can have the surface characteristics of choice, and a rubber wheel in contact with the turntable. The wheel speed, as well as the turntable speed, could be controlled precisely to generate the arbitrary values of longitudinal slip at which the dynamic coefficient of friction was measured. The correlation between the simulation and the experimental results was investigated.

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