Analysis for Water Hammer considering the effect of Fluid Structure Interaction in Straight Pipes (original) (raw)
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International Journal of Pressure Vessels and Piping, 2020
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WATER-HAMMER WITH FLIUD STRUCTURE INTERACTION IN THICK WALLED PIPES
A one-dimensional mathematical model is presented which describes the acoustic behaviour of thickwalled liquid-filled pipes. The model is based on conventional water-hammer and beam theories. Fluidstructure interaction (FSI) is taken into account. The equations governing straight pipes are derived by the cross-sectional integration of axisymmetric two-dimensional basic equations. The resulting FSI four-equation model has small correction terms and factors accounting for the wall thickness. Exact solutions of this model show that these corrections are important only for very thick pipes, with, say, a radius/thickness ratio smaller than 2.
Numerical and Experimental Study of Water Hammer in Viscoelastic Pipes
Analysis of unsteady flow helps in designing pipe systems to withstand additional loads resulting from the water hammer phenomenon, as it can damage pipes severely and causes fittings rupture. Performing this analysis requires, firstly, performing a steady-state analysis to get the initial values to start the unsteady-state analysis. The present study introduces the development of a model, using the Gradient Method, and a FORTRAN code to perform steady-state network analysis. The developed code is a development of the code presented by Larock et al. (2000), which used the Newton-Raphson method. The code is validated by comparing its results with Bryan et al. (2006) case study results. The comparison showed that the maximum error was 0.125%; therefore the validation of code is verified. The mechanical behavior of the pipe material affects the pressure response of a fluid system during water hammer. Traditionally, the unsteady-state analysis to simulate water hammer focused on applyin...
Parameters affecting water hammer in metal pipelines
E3S Web of Conferences
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.
Water Hammer Analysis by Characteristic Method
American Journal of Engineering and Applied Sciences, 2008
Rapid changes in the velocity of fluid in closed conduits generate large pressure, which are transmitted through the system with the speed of sound. When the fluid medium is a liquid the pressure surges and related phenomena are described as water hammer. Water hammer is caused by normal operation of the system, such as valve opening or closure, pump starts and stoppages and by abnormal condition, such as power failure. Problem statement: Water hammer causes the additional pressure in water networks. This pressure maybe defects on pipes and connections. The likely effects of water hammer must be taken into account in the structural design of pipelines and in the design of operating procedures for pumps, valves, etc. Approach: The physical phenomena of water hammer and the mathematical model which provides the basis for design computations are described. Most water hammer analysis involves computer solution by the method of characteristics. In this study water hammer is modelled with this method and effect of valve opening and closure will be surveyed with a program that is used for this purpose and with a numerical example. Results: The more rapid the closure of the valve, the more rapid is the change in momentum and hence, greater is the additional pressure developed. Conclusions/Recommendations: For preventing of water hammer defects, is recommended that valves should be open or closed slowly. Also with using the method of characteristics, we can modelled all pipe networks, and see the affects of water hammer.
Experimental Study of Water Hammer Pressure in a Commercial Pipe
Water hammer is a phenomenon caused by change in flow velocity and valve closing/opening time. It is undesirable. It causes because pressure transient in the pipe, vibration and noise. Excessive pressure causes pipe fracture by rupture. A review of literature has shown that earlier researchers concentrated more on the analysis of water hammer by method of characteristic while comparative study of method of water hammer analysis is insufficient. In the present study experimental and analytical analysis of water hammer pressure in a commercial pipe has been studied and analyzed. Method of characteristic (MOC), arithmetic method, theoretical method and experimental method are used in this thesis. In MOC, an element-wise definition is used for all the devices that may be used in a pipeline system and the corresponding equations are derived in an element-wise manner. The proper equations defining the behavior of each device including pipes are derived and assembled to form the final system of equations to be solved for the unknown nodal heads. Used method allows for any arbitrary combination of devices in the pipeline system. MOC was concluded it is superior to other methods. Keywords: flow control valve, pipeline system and valve closing time/valve opening time.
Bulletin of the Faculty of Engineering. Mansoura University
In the present paper, the continuity and momentum equations were solved using the Method of Characteristics to simulate the water hammer phenomenon taking into account the effect of pipe wall viscoelasticity and unsteady friction of fluid flow. In order to study the effect of extended blockage existence in the pipeline, a MATLAB code was developed to deal with both cases: simple single pipeline and compound series pipes. Because of the vital role that boundary conditions play in the profile of the generated pressure wave, they were mentioned in this paper. Code developed was validated
Some aspects of physical and numerical modeling of water hammer in pipelines
Nonlinear Dynamics, 2009
In this work, a computational method was used for the prediction of water transmission failure. The proposed method allowed for any arbitrary combination of devices in the water pipeline system. The method used was by a scale model and a prototype (real) system for a city main water pipeline where transient flow was caused by the failure of a transmission system.
SIMULATION OF WATER HAMMER IN VISCOELASTIC PIPES
The mechanical behavior of the pipe material affects the pressure response of a fluid system during water hammer. In viscoelastic pipes, the pressure fluctuations are rapidly attenuated and the pressure wave is delayed in time. This is due to the retarded deformation of the pipe-wall. In this work, a mathematical model to simulate water hammer in viscoelastic pipes taking into account the viscoelastic behavior of pipe walls, applying the Kelvin-Voigt model, has been developed. The developed model was solved using the Method of Characteristics (MOC), neglecting fluid-structure interactions (FSI) and unsteady friction effects. The model results were tested against the experimental results obtained by Covas et al. , which carried out on a high density polyethylene (HDPE) pipe-rig at Imperial College, London. The effects of time step and wave speed were studied. The pressure fluctuation obtained with the proposed viscoelastic model showed a good agreement with the experimental results. Conversely, the pressure obtained by the elastic model solution showed a large discrepancy with the experimental and numerical data. The time step affected the pressure-head wave amplitude and frequency, while wave speed affected only the wave frequency. The best results were obtained at higher time step values, corresponding to a Courant number ranging from 0.983 to unity, as the average amplitude and frequency of the numerical solution are 96% and 95.1% of their corresponding values for the experimental results, respectively. The best wave speed was at about 388.7 m/s.