Water hammer simulation by implicit method of characteristic

Afshar, M. H.; Rohani, M.

doi:10.1016/j.ijpvp.2008.08.006

Cited by 110 publications

(61 citation statements)

References 13 publications

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“…The unknown parameters ∆QN and ∆HN are obtained by combining the outlet boundary condition f(QN, HN) = 0.0 and Equation (13). ∆HN−1 can be solved by Equation (12), then ∆QN−1 can be obtained by Equation (11).…”

Section: Solution Methodsmentioning

confidence: 99%

“…Rohani and Afshar [12] proposed a point-implicit method of characteristics (PIMOC) to calculate the transient flow caused by the closure of a valve and the failure of a pump system. They found that the PIMOC required less computational effort compared with the original implicit method of characteristics ( [13]) due to the reduced size of the nonlinear system of equations while yielding the same results. FD methods are also widely used in numerical simulations.…”

Section: Introductionmentioning

confidence: 94%

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Simulation of Water Level Fluctuations in a Hydraulic System Using a Coupled Liquid-Gas Model

Wang

Yang

Nilsson

2015

Water

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Abstract:A model for simulating vertical water level fluctuations with coupled liquid and gas phases is presented. The Preissmann implicit scheme is used to linearize the governing equations for one-dimensional transient flow for both liquid and gas phases, and the linear system is solved using the chasing method. Some classical cases for single liquid and gas phase transients in pipelines and networks are studied to verify that the proposed methods are accurate and reliable. The implicit scheme is extended using a dynamic mesh to simulate the water level fluctuations in a U-tube and an open surge tank without consideration of the gas phase. Methods of coupling liquid and gas phases are presented and used for studying the transient process and interaction between the phases, for gas phase limited in a chamber and gas phase transported in a pipeline. In particular, two other simplified models, one neglecting the effect of the gas phase on the liquid phase and the other one coupling the liquid and gas phases asynchronously, are proposed. The numerical results indicate that the asynchronous model performs better, and are finally applied to a hydropower station with surge tanks and air shafts to simulate the water level fluctuations and air speed.

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Section: Solution Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Simulation of Water Level Fluctuations in a Hydraulic System Using a Coupled Liquid-Gas Model

Wang

Yang

Nilsson

2015

Water

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“…The Implicit MOC was proposed by Afshar and Rohani [1] and aims to alleviate the shortcomings and limitations of the mostly used conventional MOC. It allows for any arbitrary combination of devices in the pipeline system.…”

Section: Solving Strategy Of the Four Equationsmentioning

confidence: 99%

“…Examples include after sudden valve opening or closure, starting or stopping of pumps or turbines, mechanical failure of an item, rapid changes in demand condition, etc. [1]. The main components of these disturbances are pressure and flow changes that bring about propagation of pressure waves throughout the system, and velocity of this wave may exceed 1000 m/s, which may lead to severe damages [1,2].…”

Section: Introductionmentioning

confidence: 99%

“…[1]. The main components of these disturbances are pressure and flow changes that bring about propagation of pressure waves throughout the system, and velocity of this wave may exceed 1000 m/s, which may lead to severe damages [1,2]. Since within any pipeline system head and flow distribution in the system is predicted at different operating conditions, the modeling of these phenomena is possible and is pursued in this paper.…”

Section: Introductionmentioning

confidence: 99%

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Case studies for solving the Saint-Venant equations using the method of characteristics: pipeline hydraulic transients and discharge propagation

Barros¹,

Filho²,

Santos³

et al. 2015

International Journal of Fluid Machinery and Systems

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This study aims to present a hydraulic transitory study as MOC applications for solving the Saint-Venant equations in two case studies: 1) in a penstock of a small hydropower system as a simple pipeline in the case of valve-closure in the downstream boundary with a reservoir in the upstream boundary; and 2) for discharge propagation into a channel by velocity and depth of the flow channel along space evaluation. The proposed methodology by Chaudry [5] concerning the development of hydrodynamic models was used. The obtained results for first and second case study has been confirmed that MOC numerical approach is useful for several engineering purposes, including cases of hydraulic transients and discharge propagation in hydraulic systems.

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Numerical simulation of the effects of vaporization on the motion of PIG during pigging process

Deng

Gong

Zhou

et al. 2014

Asia-Pacific J Chem Eng

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During the course of pigging after water pressure test, when pressure drops to vapor pressure, localized vaporization always occurs at pipeline terminations or at physical high points in the pipeline. PIG is most effective when it runs at a near constant speed. The appearance of a vapor region may dramatically affect the PIG motion and ultimately contribute to impulse pressures at the end of pigging process. Large pressures may cause the PIG to run at extremely high speed, which is a highly dangerous situation. Further, the pigging efficiency can be compromised. The proposed model for estimating the pig dynamics takes into account vaporization. The basic equations governing the conservation of mass and momentum for the gas and liquid fluids were solved together with the momentum equations for the pig by applying the method of characteristics. Moreover, the new pigging model takes advantage of discrete-vapor-cavity model to predict the vaporization and location of vapor region. Numerical simulation results for gas-liquid pipeline pigging process are in good agreement with field data to validate the model developed. The model also contains the capability of PIG tracking and the prediction of impulse pressures, which can help the operator to control the PIG speed before it reaches the end of the pipeline.

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Water hammer simulation by implicit method of characteristic

Cited by 110 publications

References 13 publications

Simulation of Water Level Fluctuations in a Hydraulic System Using a Coupled Liquid-Gas Model

Simulation of Water Level Fluctuations in a Hydraulic System Using a Coupled Liquid-Gas Model

Case studies for solving the Saint-Venant equations using the method of characteristics: pipeline hydraulic transients and discharge propagation

Numerical simulation of the effects of vaporization on the motion of PIG during pigging process

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