Theoretical and Experimental Study of Steam Condensation Induced Water Hammer Phenomena (original) (raw)
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Experimental and theoretical study of steam condensation induced water hammer phenomena
Nuclear Engineering and Design, 2010
We investigate steam condensation induced water hammer (waha) phenomena and present experimental and theoretical results. Some of the experiments were performed in the PMK-2 facility, which is a full-pressure thermohydraulic model of the nuclear power plant of VVER-440/312 type and located in the Atomic Energy Research Institute Budapest, Hungary. Other experiments were done in the ROSA facility in Japan. On the theoretical side waha is studied and analyzed with the WAHA3 model based on two-phase flow six first-order partial differential equations that present one dimensional, surface averaged mass, momentum and energy balances. A second order accurate high-resolution shock-capturing numerical scheme was applied with different kind of limiters in the numerical calculations. The applied two-fluid model shows some similarities to Relap5 which is widely used in the nuclear industry to simulate nuclear power plant accidents. Experimentally measured and theoretically calculated waha pressure peaks are in qualitative agreement.
Multiple condensation induced water hammer events, experiments and theoretical investigations
Kerntechnik, 2011
We investigate steam condensation induced water hammer (CIWH) phenomena and present experimental and theoretical results. Some of the experiments were performed in the PMK-2 facility, which is a full-pressure thermalhydraulic model of the nuclear power plant of VVER-440/312 type and located in the Atomic Energy Research Institute Budapest, Hungary. Other experiments were done in the ROSA facility in Japan. On the theoretical side CIWH is studied and analyzed with the WAHA3 model based on two-phase flow six first-order partial differential equations that present one dimensional, surface averaged mass, momentum and energy balances. A second order accurate high-resolution shock-capturing numerical scheme was applied with different kind of limiters in the numerical calculations. The applied two-fluid model shows some similarities to RELAP5 which is widely used in the nuclear industry to simulate nuclear power plant accidents. New features are the existence of multiple, independent CIWH ...
Numerical simulation of condensation induced water hammer
FME Transactions, 2008
A numerical model for the simulation and analysis of the water hammer in the pipe two-phase flow is developed. The modelling is based on onedimensional homogeneous model of two-phase flow, tracking of the interface between steam volume and water column and modelling of the direct condensation of steam on subcooled liquid. The mass, momentum and energy conservation equations are solved by the method of characteristics. For these three equations, there are three characteristic directions: two of them are determined by the pressure wave propagation and the third one by the fluid particle propagation. The fluid particle and the steam-water interface tracking are obtained through the energy conservation equation solving in space, with the accuracy of the third degree. The value of thermodynamic quality is used to determine whether the observed computational region is filled with water, two-phase mixture or steam. The term in the energy conservation equation, which contains information about the heat exchanged between steam and liquid phase through condensation, is determined by integration of superficial heat flux over steam-water interface. The model is applied to the simulation and analysis of the air-water interface propagation in the experimental apparatus of oscillating manometer and the condensation induced water hammer in a vertical pipe for draining of steam into the pool filled with subcooled water.
Initiation of Water Hammer in a Steam/Water Pipe with a Non-Condensable Gas
2000
The effect of a non-condensable gas on the initiation of water hammer in a condensing water-steam system has been investigated by extending Bjorge's work. Based on computational results, it is concluded that the pipe slope is the dominant parameter which affects the initiation of water hammer. The effective temperature difference in driving energy across the liquid interface was found to
Simulation of water hammer experiments using RELAP5 code
2005
The rapid closing or opening of a valve causes pressure transients in pipelines. The fast deceleration of the liquid results in high pressure surges upstream the valve, thus the kinetic energy is transformed into the potential energy, which leads to the temporary pressure increases. This phenomenon is called water hammer. The intensity of water hammer effects will depend upon the rate of change in the velocity or momentum. Generally water hammer can occur in any thermal-hydraulic systems and it is extremely dangerous for the thermalhydraulic system since, if the pressure induced exceeds the pressure range of a pipe given by the manufacturer, it can lead to the failure of the pipeline integrity. Due to its potential for damage of pipes, water hammer has been a subject of study since the middle of the nineteenth century. Many theoretical and experimental investigations were performed. The experimental investigation of the water hammer tests performed at Fraunhofer Institute for Environmental, Safety and Energy Technology (UMSICHT) [1] and Cold Water Hammer experiment performed by Forschungszentrum Rossendorf (CWHTF) [2] should be mentioned. The UMSICHT facility in Oberhausen was modified in order to simulate a piping system and associated supports that are typical for a nuclear power plant [3]. The Cold water hammer experiment is interesting and instructive because it covers a wide spectrum of particularities. One of them is sub-cooled water interaction with condensing steam at the closed end of the vertical pipe at room temperature and corresponding saturation pressure [4]. In the paper, the capabilities of RELAP5 code to correctly represent the water hammer phenomenon are presented. Paper presents the comparison of RELAP5 calculated and measured at UMSICHT and CWHTF test facilities pressure transient values after the fast closure (opening) of valves. The analyses of rarefaction wave travels inside the pipe and condensation of vapour bubbles in the liquid column are presented. The influence of the control volume sizes in pipe components to the computational results is presented as well. The acquirement of knowledge will allow to develop RELAP5 code model for the analysis of accidents with the phenomenon of water hammer for the nuclear power plants.
Nuclear Engineering and Design, 2008
The capabilities of the nuclear system transient codes TRACE and RELAP5 to model coupled two-phase flow and pressure wave propagations in a pipe are assessed by analyzing the UMSICHT PPP cavitation water hammer experiments 329 and 135 after valve closure. Time-dependent pressure, flow behaviour, and the generation and collapse of vapor bubbles at the valve and the first bridge are discussed. We show that both codes are able to model the flow behaviour of the water hammer for the high pressure and high temperature case 329 (initially 10-13 bar and 420 K), however condensation heat transfer for the base case needed to be increased in order to accurately model the magnitude of the first pressure excursion. The experimental broadening and damping of the subsequent pressure peaks by Fluid-Structure Interaction (FSI) phenomena arising from the interaction of the flow with the vibrations of the piping structure are not considered in the modeling results. For the lower pressure and temperature case 135 (initially 1-4 bar and 294 K), the TRACE code provides a good approximation of the propagation of the pressure wave and the void fraction behaviour, already with base case conditions, while RELAP5 overpredicts the vapor generation along the pipe and, as a result, considerably underpredicts the pressure amplitudes and overpredicts the water hammer frequency.
The Proceedings of the International Conference on Nuclear Engineering (ICONE), 2007
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.
Fluid-structure interaction for water hammers effects in petroleum and nuclear plants
The International Journal of Multiphysics, 2011
Fluid-Structure Interaction (FSI) becomes more and more the focus of computational engineering in Petroleum and Nuclear Industry in the last years. These problems are computer time consuming and require new stable and accurate coupling algorithms to be solved. For the last decades, the new development of coupling algorithms, and the increasing of computer performance have allowed to solve some of these problems and some more physical applications that has not been accessible in the past; in the future this trend is supposed to continue to take into account more realistic problem. In this presentation, numerical simulation using FSI capabilities in LS-DYNA, of hydrodynamic ram pressure effect occurring in nuclear industry is presented.