scholarly journals Parameters affecting water hammer in metal pipelines

2018 ◽  
Vol 44 ◽  
pp. 00183
Author(s):  
Kamil Urbanowicz ◽  
Mateusz Firkowski
Keyword(s):  
Numerical Modelling ◽  
Method Of Characteristics ◽  
Water Hammer ◽  
Supply System ◽  
Hydraulic Systems ◽  
Wave Pressure ◽  
Hydraulic Machinery ◽  
Metal Pipes ◽  
The Individual ◽  
Pressure Changes

The water hammer related to rapid wave pressure changes in hydraulic systems have been subjected to intensive research for more than a hundred years. Nevertheless, a large number of new papers appear each year. Current literature indicates model differences resulting from the used material of the pipe. In the hydraulic machinery, elastic (metal) pipes are usually used, while water transport in water supply system is currently realized with pipes whose deformation of the walls is viscoelastic. In this paper, the individual and group impact of all parameters influencing the results of numerical modelling of the water hammer occurring in the pipes will be analysed. The method of characteristics will be used to solve partial differential equations describing the flow.

scholarly journals Modern Modeling of Water Hammer

2017 ◽  
Vol 24 (3) ◽  
pp. 68-77 ◽  
Author(s):  
Kamil Urbanowicz
Keyword(s):  
Side Effects ◽  
Adverse Effects ◽  
Water Hammer ◽  
Hydraulic Systems ◽  
Weighting Functions ◽  
Transient Flows ◽  
Hydraulic Equipment ◽  
Pressure Changes ◽  
The Impact ◽  
Reduced Pressures

Abstract Hydraulic equipment on board ships is common. It assists in the work of: steering gear, pitch propellers, watertight doors, cargo hatch covers, cargo and mooring winches, deck cranes, stern ramps etc. The damage caused by transient flows (which include among others water hammer) are often impossible to repair at sea. Hence, it is very important to estimate the correct pressure runs and associated side effects during their design. The presented study compares the results of research on the impact of a simplified way of modeling the hydraulic resistance and simplified effective weighting functions build of two and three-terms on the estimated results of the pressure changes. As it turns out, simple effective two-terms weighting functions are able to accurately model the analyzed transients. The implementation of the presented method will soon allow current automatic protection of hydraulic systems of the adverse effects associated with frequent elevated and reduced pressures.

scholarly journals Water hammer protective performance of a spherical air vessel caused by a pump trip

2019 ◽  
Vol 19 (6) ◽  
pp. 1862-1869 ◽  
Author(s):  
Lin Shi ◽  
Jian Zhang ◽  
Xiaodong Yu ◽  
Sheng Chen
Keyword(s):  
Water Supply ◽  
Method Of Characteristics ◽  
Water Hammer ◽  
Supply System ◽  
Long Distance ◽  
Effective Measure ◽  
Gas Volume ◽  
Protective Performance ◽  
Force Characteristics ◽  
Control Water

Abstract The use of air vessels is an effective measure to control water hammer in a long-distance water supply system. The traditional shape of such vessels is cylindrical. In this paper, an innovative spherical air vessel is proposed to improve the force characteristics of the tank. A mathematical model of the spherical air vessel was established using the method of characteristics. A comparison was performed of water-hammer protection performance between the spherical air vessel and the cylindrical air vessel based on a practical water supply project. Furthermore, a sensitivity analysis on the parameters of the spherical air vessel was performed. The results showed that the spherical air vessels had better protective performance compared with the cylindrical air vessels. Under the same protection requirements, the spherical air vessel can reduce the total volume and surface area by more than 10%. In addition, for a fixed volume of the spherical air vessel, the protective effect improves with the increase of the initial gas volume. Increasing the connecting pipe diameter of the air vessel is beneficial for low-pressure protection, whereas it is adverse to high-pressure protection; in contrast, altering the installation elevation has little effect on water-hammer protection.

Averaging and integral manifolds

1970 ◽  
Vol 2 (2) ◽  
pp. 197-222 ◽  
Author(s):  
W. A. Coppel ◽  
K. J. Palmer
Keyword(s):  
Autonomous System ◽  
Method Of Characteristics ◽  
Integral Manifold ◽  
Artificial Viscosity ◽  
Original Method ◽  
Method Of Averaging ◽  
System Of Differential Equations ◽  
Viscosity Term ◽  
Integral Manifolds ◽  
The Individual

An integral manifold for a system of differential equations is a manifold such that any solution of the equations which has a point on it is entirely contained on it. The method of averaging establishes the existence of such a manifold for a system which is a perturbation of an autonomous system with a periodic orbit. The existence of the manifold is established here under more general hypotheses, namely for perturbations which are ‘integrally small’. The method differs from the original method of Bogolyubov and Mitropolskii and operates directly with the individual solutions. This is made possibly by the use of an appropriate norm, and is equivalent to solving the partial differential equation which occurs in work by Moser and Sacker by the method of characteristics rather than by the introduction of an artificial viscosity term. Moreover, detailed smoothness properties of the manifold are obtained. For periodic perturbations the integral manifold is a torus and these smoothness properties are just sufficient to permit the application of Denjoy's theorem.

scholarly journals Freezing of the Subballast Layers of the Railway Formation – High Embankment and Double Track

2019 ◽  
Vol 15 (1) ◽  
pp. 5-12
Author(s):  
Stanislav Hodás ◽  
Alžbeta Pultznerová
Keyword(s):  
Numerical Modelling ◽  
Winter Period ◽  
Temperature Transition ◽  
Temperature Behaviour ◽  
The Core ◽  
Modelling Experiment ◽  
The Individual ◽  
Double Track

AbstractIn the paper, a numerical modelling experiment is presented in order to detect the temperature transition through the individual layers of the railway formation during the winter period that is their undesirable freezing. In the experiment, the temperature behaviour and the zero isotherm (0 °C) are investigated. We want to prove that the temperatures are also affected by the volume of mass in the railway formation. The modelling of new experiment has been carried out done on a low and also high embankment of single and double track railway, where the volume of material in the core of the formation is almost doubled. The experiment demonstrated that the greater is the mass of the subballast layers, the higher is the resistance to freezing due to the accumulated heat in the pre-winter period.

scholarly journals Investigation on Water Hammer Control of Centrifugal Pumps in Water Supply Pipeline Systems

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 108 ◽  
Author(s):  
Wuyi Wan ◽  
Boran Zhang ◽  
Xiaoyi Chen
Keyword(s):  
Water Supply ◽  
Method Of Characteristics ◽  
Water Hammer ◽  
Moment Of Inertia ◽  
Evaluation Methodology ◽  
Centrifugal Pumps ◽  
Positive Effects ◽  
Pipeline Systems ◽  
The Moment ◽  
Water Supply Pipeline

Water hammer control in water supply pipeline systems is significant for protecting pipelines from damage. The goal of this research is to investigate the effects of pumps moment of inertia design on pipeline water hammer control. Based on the method of characteristics (MOC), a numerical model is established and plenty of simulations are conducted. Through numerical analysis, it is found that increasing the pumps moment of inertia has positive effects both on water hammer control as well as preventing pumps rapid runaway speed. Considering the extra cost of space, starting energy, and materials, an evaluation methodology of efficiency on the increasing moment of inertia is proposed. It can be regarded as a reference for engineers to design the moment of inertia of pumps in water supply pipeline systems. Combined with the optimized operations of the valve behind the pumps, the pipeline systems can be better protected from accident events.

Numerical Modelling of Water Hammer Using Differential Quadrature Method

2007 ◽  
Author(s):  
M. R. Hashemi ◽  
M. J. Abedini ◽  
Theodore E. Simos ◽  
George Psihoyios ◽  
Ch. Tsitouras
Keyword(s):  
Numerical Modelling ◽  
Differential Quadrature Method ◽  
Water Hammer ◽  
Differential Quadrature ◽  
Quadrature Method

Analysis of hydraulic systems on the basis of the decomposition method

2015 ◽  
Vol 8 (2) ◽  
pp. 34-37 ◽  
Author(s):  
Сазонова ◽  
Svetlana Sazonova
Keyword(s):  
Complex Systems ◽  
Boundary Conditions ◽  
Decomposition Method ◽  
Internal Communication ◽  
Target Product ◽  
Hydraulic Systems ◽  
Decomposition Approach ◽  
The Status ◽  
The Individual ◽  
System Nodes

Hydraulic systems belong to the category of complex systems, between the individual elements of the histories and subsystems exist internal communication, precluding the possibility of an Autonomous fashion from cancellation. The scale of such systems and their development trends lead to the inevitable decomposition approach. Research is not always to be the whole system, and some of its fragments, which border taking into account the accepted scheme of allocation of the target product to consumers submit a set of system nodes. In this case, the nodes acquire the status of power units, because through them there is an exchange of energy between IP investigated fragment of the system and the metasystem. Examines the emerging conflict between the need for a complementary decomposition and inner interconnection of all elements. He is overcome by the imposition of conditions one of znanosti, including boundary conditions.

Truncated Method of Characteristics for Quasi-Two-Dimensional Water Hammer Model

2014 ◽  
Vol 140 (6) ◽  
pp. 04014013 ◽  
Author(s):  
Radoslav Korbar ◽  
Zdravko Virag ◽  
Mario Šavar
Keyword(s):  
Method Of Characteristics ◽  
Water Hammer ◽  
Two Dimensional

Accuracy of the Operator Splitting Technique for Two-Phase Flow With Stiff Source Terms

2002 ◽  
Author(s):  
Iztok Tiselj ◽  
Andrej Horvat
Keyword(s):  
Two Phase Flow ◽  
Fluid Model ◽  
Operator Splitting ◽  
Splitting Method ◽  
Water Hammer ◽  
Phase Flow ◽  
Hydraulic Systems ◽  
Source Terms ◽  
Two Phase ◽  
Splitting Technique

Code for analysis of the water hammer in thermal-hydraulic systems is being developed within the WAHALoads project founded by the European Commission [1]. Code will be specialized for the simulations of the two-phase water hammer phenomena with the two-fluid model of two-phase flow. The proposed numerical scheme is a two-step second-order accurate scheme with operator splitting; i.e. convection and sources are treated separately. Operator splitting technique is a very simple and “easy-to-use” tool, however, when the source terms are stiff, operator splitting method becomes a source of a specific non-accuracy, which behaves as a numerical diffusion. This type of error is analyzed in the present paper.

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