Experimental evaluation of ability of Relap5, Drako®, Flowmaster2™ and program using unsteady wall friction model to calculate water hammer loadings on pipelines

Marcinkiewicz, Jerzy; Adamowski, Adam; Lewandowski, Mariusz

doi:10.1016/j.nucengdes.2007.10.027

Cited by 17 publications

(6 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Theoretically, the relationship between the closure time and the return time of the reflected wave makes it possible to distinguish precisely between two kinds of the phenomenon. Furthermore, the extension of the closure time is one of the most commonly used methods for reducing the maximum pressure increase (or minimum pressure decrease) (Marcinkiewicz et al 2008, Pires et al 2004. However, this seemingly simple solution depends on the parameters of different kinds of gates and valves.…”

Section: Introductionmentioning

confidence: 99%

An Analysis of the Impact of Valve Closure Time on the Course of Water Hammer

Kodura

2016

Archives of Hydro-Engineering and Environmental Mechanics

View full text Add to dashboard Cite

The knowledge of transient flow in pressure pipelines is very important for the designing and describing of pressure networks. The water hammer is the most common example of transient flow in pressure pipelines. During this phenomenon, the transformation of kinetic energy into pressure energy causes significant changes in pressure, which can lead to serious problems in the management of pressure networks. The phenomenon is very complex, and a large number of different factors influence its course. In the case of a water hammer caused by valve closing, the characteristic of gate closure is one of the most important factors. However, this factor is rarely investigated. In this paper, the results of physical experiments with water hammer in steel and PE pipelines are described and analyzed. For each water hammer, characteristics of pressure change and valve closing were recorded. The measurements were compared with the results of calculations perfomed by common methods used by engineers - Michaud’s equation and Wood and Jones’s method. The comparison revealed very significant differences between the results of calculations and the results of experiments. In addition, it was shown that, the characteristic of butterfly valve closure has a significant influence on water hammer, which should be taken into account in analyzing this phenomenon. Comparison of the results of experiments with the results of calculations? may lead to new, improved calculation methods and to new methods to describe transient flow.

show abstract

Section: Introductionmentioning

confidence: 99%

An Analysis of the Impact of Valve Closure Time on the Course of Water Hammer

Kodura

2016

Archives of Hydro-Engineering and Environmental Mechanics

View full text Add to dashboard Cite

show abstract

“…(5), is not supported with a solid mathematical theory. It is believed that the success of the application of convolution integral models in both finitedifference Kucienska et al, 2008) and MOC schemes (Trikha, 1975;Marcinkiewicz et al, 2008) is a consequence of the relatively small magnitude of the unsteady friction terms, representing only a few percents of the main terms and the decaying shape of the weighing function W(t) in Eq. (5).…”

Section: Mathematical Modelmentioning

confidence: 99%

Integration of unsteady friction models in pipe flow simulations

Tiselj

Gale

2008

Journal of Hydraulic Research

View full text Add to dashboard Cite

Various approaches to integrate instantaneous acceleration models are examined. The basic physical model consists of the one-phase flow water hammer equations with the unsteady wall friction model of Brunone. The numerical scheme is based on characteristic upwind finite differences, representing an extension of the Godunov schemes to the non-conservative hyperbolic equations. The most accurate solutions result from the basic version of this method, which takes into account the effects of spatial and temporal derivatives of the unsteady friction term on the eigenvalues of the hyperbolic equations. A convergence analysis shows that second-order accuracy is obtained on smooth solutions with this approach, but only if the discontinuity in the unsteady friction correlation is removed. Two simpler numerical schemes treat the unsteady friction term as a source term and neglect its influence on the eigenvalues. The results obtained with the simplified schemes converge to the exact solutions, but exhibit larger numerical diffusivity than the basic version of the method. RÉSUMÉDiverses approches pour intégrer les modèles instantanés d'accélération sont examinées. Le modèle physique de base comprend les équations du coup de bélier en écoulement monophasique avec le modèle instationnaire de frottement en paroi de Brunone. Le schéma numérique est basé sur les différences finies amont des caractéristiques, représentant une extension des schémas de Godunov aux équations hyperboliques non-conservatives. Les solutions les plus précises résultent de la version de base de cette méthode, qui tient compte des effets des dérivées spatiales et temporelles du terme de frottement instationnaire sur les valeurs propres des équations hyperboliques. Une analyse de convergence prouve que l'exactitude au second ordre est obtenue sur les solutions lisses avec cette approche, mais seulement si la discontinuité dans la corrélation du frottement instationnaire est supprimée. Deux schémas numériques plus simples traitent le terme de frottement instationnaire comme un terme source et négligent son influence sur les valeurs propres. Les résultats obtenus avec les schémas simplifiés convergent vers les solutions exactes, mais présentent une plus grande diffusion numérique que la version de base de la méthode.

show abstract

“…A special attention regarding choice of time step is recommended by Relap5 developing group when very rapid processes like steam and water hammer are to be calculated (see chapter 2.1.2.2 in [4]). Correct use of Relap5 for analysing very rapid processes need application of proper cell size to resolve the wave front and time step small enough to meet the Courant limit and to minimize numerical diffusion [5,6]. It should be observed that using too small time step can bring numerical oscillations and in some cases lead to failure of the simulation [5].…”

Section: Calculations With Relap5 Drako and Comparison Withmentioning

confidence: 99%

“…A special attention has been paid to Relap5 calculations because of sensitivity of the program to numerical damping. According to recommendations in manual and [5,6] Courant number based on wave and bulk velocity, equation ( 2), has been chosen to be 0.05. For this Courant number three runs were performed with different element lengths dx: 0.29 m, 0.145 m and 0.0725 m in order to see eventual influence of spatial discretisation on calculated pressure surges.…”

Section: Pressures Calculated With Relap5 and Drakomentioning

confidence: 99%

“…When the calculation can be performed with several computer programs an important question for the reviewer (and also for the users) is knowledge about their ability to calculate the dynamic loadings and eventual differences. The ability of the basic commercial programs (Relap5 and Drako) to calculate water hammer in cases without phase changes (without liquid column separations) was presented in [6]. Furthermore it is very important to perform study of ability of the programs to calculate pressure surges in a pipeline when phase changes occur and compare with experimental data.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Icone15-10326 Experimental Evaluation of Ability of Relap5 and Drako[○!r] to Calculate Water Hammer With Phase Changes

Marcinkiewicz

Adamkowski

Lewandowski

2007

ICONE

Self Cite

View full text Add to dashboard Cite

A proper calculations of loadings caused by water hammer (hydraulic transients) occurring in pipeline systems in nuclear power plants are very important issue according to systems viability, safety and reliability. Calculating the water hammer loadings on pipe sections according to the classical one-dimensional (1D) theory of liquid transient flow in a pipeline, and then transferring the results to strength analyses of pipeline structure (walls), is nowadays the most common calculation procedure used in Sweden. This procedure assumes that the respond of the pipeline structure to the pressure surges is quasi-steady -dynamic interaction between the fluid and the pipeline construction is set aside. For calculating the hydraulic loadings in the 1D domain so-called network programs are used -Relap5 and Drako are the representatives of this kind of programs which are the most commonly used in Sweden nowadays. As a third party accredited inspection body INSPECTA NUCLEAR AB reviews all calculations of water hammer loadings. A question of vital importance for the reviewer is the knowledge about the ability of the programs to calculate the loadings under different conditions. While Relap5 and Drako calculations of the loadings without phase changes have been investigated quite well, the ability of the programs to calculate the loadings when phase changes occur cannot be considered to be sufficient. The presented work shall be seen as an attempt to illustrate the ability of Relap5 and Drako programs to calculate the water hammer with phase changes. Some parametric analyses have been performed in order to investigate the influence of digitizing of time and space. All differences between the results obtained with Relap5 and Drako are discussed. 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 comparisons of calculated and measured pressure surges show significant differences between them. The discrepancies are discussed and conclusions are presented.

show abstract

Experimental evaluation of ability of Relap5, Drako®, Flowmaster2™ and program using unsteady wall friction model to calculate water hammer loadings on pipelines

Cited by 17 publications

References 10 publications

An Analysis of the Impact of Valve Closure Time on the Course of Water Hammer

An Analysis of the Impact of Valve Closure Time on the Course of Water Hammer

Integration of unsteady friction models in pipe flow simulations

Icone15-10326 Experimental Evaluation of Ability of Relap5 and Drako[○!r] to Calculate Water Hammer With Phase Changes

Contact Info

Product

Resources

About