Initiation of Water Hammer in a Steam/Water Pipe with a Non-Condensable Gas (original) (raw)
Related papers
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.
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.
International Journal of Technology, 2015
Slugging as a water hammer initiator is a fascinating topic because it has a strategic impact on equipment safety in industrial systems, i.e. pressurized water reactors (PWR), heat exchangers, etc. The present research's objective was to investigate slugging as initiating the water hammer phenomenon through indirect contact steam condensing in a horizontal pipe heat exchanger. The experiment apparatus used in the present experimental study consisted of an inner annulus pipe made of copper (d in = 17.2 mm, d o = 19 mm) with a length of 1.8 m and an outer annulus pipe of galvanized iron (d in = 108.3 mm, d o = 114. 3 mm) with a length of 1.6 m. The tested liquid was water. The experiments were conducted at a static pressure of P s = 108.825 kPa and the temperature of T = 119.7°C. The obtained experimental data of temperature and differential pressure fluctuations were analyzed using statistical analysis. The results were as follows: 1) the flow pattern area of non-slugging (stratified and wavy flow), transition (wavy-slug flow), and slugging (slug and large-slug) were determined, with the transition flow pattern of slug and large-slug defined as initiating water hammer; 2) transition area ranges for the wavy-slug flow pattern are from ṁ co =110-1 kg/s to ṁ co =610-1 kg/s for ṁ st =610-3 kg/s to ṁ st =7.510-3 kg/s, and ṁ co < 310-1 kg/s for ṁ st =810-3 kg/s to ṁ st =910-3 kg/s. These obtained data are very important in order to develop a database for the input of an early warning system design in a safe, two-phase flow installation piping system during steam condensation.
Theoretical and Experimental Study of Steam Condensation Induced Water Hammer Phenomena
2008
We investigate steam condensation induced water hammer (waha) phenomena and present experimental and theoretical results. 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. The present experimental setup is capable to measure water hammer phenomena in a wide range of steam pressure, cold water temperate and floating mass rate at a high level of accuracy. 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 nucle...
A parametric study and a guide chart to avoid condensation-induced water hammer in a horizontal pipe
An experimental and analytical studies on the condensation-induced water hammer (CIWH) for steam-water countercurrent flow in a nearly horizontal circular pipe have been performed. A total of 17 experimental data for the onset of slugging, which is assumed to be the precursor of the CIWH, have been obtained for various flow rates of water. Incorporating the most recent correlations of interfacial heat transfer and friction factor developed for a circular geometry and using an improved criterion of transition from stratified to a slug flow, two existing analytical models to predict lower and upper bounds for CIWH have been upgraded. Applicability of the present as well as existing CIWH models has been tested by comparison with two sets of CIWH data. The result of this comparison shows that the applicability of the present as well as existing models is reasonably good. Based on the present models for CIWH, a computer code entitled as 'KAIST-CIWH' has been developed and sample guide charts to find CIWH free regions for a given combination of major flow parameters in a long horizontal pipe have been presented along with the results of parametric studies of major parameters (D, P, T f,in , and L/D) on the critical inlet water flow rate (W f,in ) crit for both lower and upper bounds. In addition, two simple formulas for lower and upper bounds that can be used in an emergency for quick results have been presented.
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 ...
Analysis for Water Hammer considering the effect of Fluid Structure Interaction in Straight Pipes
2012
I would like to express my deep sense of gratitude and respect to my supervisor Prof. J.Srinivas for his excellent guidance, valuable suggestions and endless support. I am also thankful to Prof. S. Chakraborty, Department of Mathematics, NIT Rourkela for his constant support and encouragement. Last, but not the least I extend my sincere thanks to other faculty members of the Department of Mechanical Engineering, NIT Rourkela and my dear friends for their valuable advice in every stage for successful completion of this project report.
Numerical investigation of temperature effect on water hammer with cavitation in copper pipe rig
2021
The paper investigates temperature effect on water hammer in an isothermal pressurized copper pipe rig, for single and two phase flow. The study concerns pressure wave’s intensity, celerity and attenuation. Also, the cavities volume created during low pressure periods is inspected. The mathematical model of hyperbolic equations is described by the dynamic and continuity equations, which have been transformed by the characteristics method (MOC) into ordinary differential equations. Water hammer solver was built considering two different models of cavitation and column separation, the discrete vapor cavity model (DVCM) and the discrete gas cavity model (DGCM). In addition of the quasi-steady friction model, two unsteady friction models were incorporated into the code, the convolution based model proposed by Vardy & Brown and the instantaneous acceleration model proposed by Brunone. The simulations concern temperature range within 4°C to 95°C. Although the single and the two phase wate...
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.
EXPERIMENTAL STUDIES ON THE IMPACT OF CHANGING THE PIPE MATERIAL ON THE PROPAGATION OF THE PRESSURE WAVE DURING WATER HAMMER, 2018
Aim of the paper is to present the results studying the water hammer phenomenon in pipes made of different materials, and to show the impact of changing the type of material of the pipe on the velocity of the pressure wave during the transient flow in the pipes. In terms of research material and methods, pipes made of galvanized steel and high-density polyethylene were tested. Measurements were made using strain gauges with a high accuracy of measurement. The results of the pressure wave velocity range from 205 to 247 m/s for the polyethylene pipe, and from 426 to 1351 m/s for the steel pipe. Therefore, the change in the type of the pipe material has a significant effect on the velocity of the pressure wave during the water hammer. The value of this velocity is influenced not only by the properties of the material itself or of the liquid, but also of the length of the sections and their position relative to each other. It is evident that the velocity in the polyethylene pipe does not change significantly in relation to the situation where the pipe has constant material characteristics. The situation is radically different in the case of a steel pipe, where the velocity of the pressure wave changes along with the length of the pipe and its position relative to the tank. The lowest value of the velocity in the elastic pipe is achieved when the latter is on the valve side and is only 13.15 m long, while the highest value is reached when the 13.24 m steel pipe is located on the side of the tank.