Development of Numerical Simulation for Jet Breakup Behavior in Complicated Structure of BWR Lower Plenum: (4) Multi-Channel Experimental Analysis by Detailed Two-Phase Analysis Code TPFIT

2014 ◽  
Author(s):  
Takayuki Suzuki ◽  
Hiroyuki Yoshida ◽  
Fumihisa Nagase ◽  
Yutaka Abe ◽  
Akiko Kaneko
Keyword(s):  
High Speed ◽  
Evaluation Method ◽  
Simulation Method ◽  
Severe Accident ◽  
Interface Tracking ◽  
Phase Flow ◽  
Complicated Structure ◽  
Two Phase ◽  
Support Plate ◽  
Multi Phase

In order to improve the safety of Boiling Water Reactor (BWR), it is required to know the behavior of the plant when an accident occurred as can be seen at Fukushima Daiichi nuclear power plant accident. Especially, it is important to estimate the behavior of molten core jet in the lower part of the reactor pressure vessel at a severe accident. In the BWR lower plenum, the flow characteristics of molten core jet are affected by many complicated structures, such as control rod guide tubes, instrument guide tubes and core support plate. However, it is difficult to evaluate these effects on molten core jet experimentally. Therefore, we considered that multi-phase computational fluid dynamics approach is the best way to estimate the effects on molten core jet by complicated structure. The objective of this study is to develop the evaluation method for the flow characteristic of molten core jet including the effects of the complicated structures in the lower plenum. So we are developing a simulation method to estimate the behavior of molten core jet falling down through the core support plate to the lower plenum of the BWR. The simulation method is based on interface tracking method code TPFIT (Two Phase Flow simulation code with Interface Tracking). To verify and validate the applicability of the developed method in detail, it is necessary to obtain the experimental data that can be compared with detailed numerical results by the TPFIT. Thus, the authors are carrying out experimental works by use of multi-phase flow visualization technique. In the experiments, time series of interface shapes are observed by high speed camera and velocity profiles in/out of the jet are measured by the PIV method. In this paper, we carried out analysis of the multi-channel experiment using the analytical method based on the TPFIT. Specifically, predicted results including interface shape and velocity profile in and out simulated molten material were compared with measured results. In the results, predicted results agreed with measured results qualitatively.

Development of Numerical Simulation for Jet Breakup Behavior in Complicated Structure of BWR Lower Plenum: 1 — Preliminary Analysis of Jet Breakup Behavior in Complicated Structure by TPFIT

2013 ◽  
Author(s):  
Takayuki Suzuki ◽  
Hiroyuki Yoshida ◽  
Fumihisa Nagase ◽  
Yutaka Abe ◽  
Akiko Kaneko
Keyword(s):  
High Speed ◽  
Measured Data ◽  
Severe Accident ◽  
Interface Tracking ◽  
Phase Flow ◽  
Complicated Structure ◽  
Support Plate ◽  
Jet Breakup ◽  
Multi Phase ◽  
Developing Method

In order to improve the safety of Boiling Water Reactor (BWR), it is required to know the behavior of the plant when an accident occurred as can be seen at Fukushima Daiichi nuclear power plant accident. Especially, it is important to estimate the behavior of molten core jet in the lower part of the containment vessel at severe accident. In the BWR lower plenum, the flow characteristics of molten core jet are affected by many complicated structures, such as control rod guide tubes, instrument guide tubes and core support plate. However, it is difficult to evaluate these effects on molten core jet experimentally. Therefore, we considered that multi-phase computational fluid dynamics approach is the best way to estimate the effects on molten core jet by complicated structure. The objective of this study is to develop the evaluation method for the flow characteristic of molten core jet including the effects of the complicated structures in the lower plenum. So we are developing a simulation method to estimate the behavior of molten core jet falling down through the core support plate to the lower plenum of the BWR. The method has been developed based on interface tracking method code TPFIT (Two Phase Flow simulation code with Interface Tracking). To verify and validate the applicability of the developed method in detail, it is necessary to obtain the experimental data that can be compared with detailed numerical results by the TPFIT. Thus, in this study, we are carrying out experimental works by use of multi-phase flow visualization technique. In the experiments, time series of interface shapes are observed by high speed camera and velocity profiles in/out of the jet will be measured by the PIV method. In this paper, the outline of the developing method based on the TPFIT was explained. And, the developing method was applied to preliminary experiment with/without modeled complicated structures. As the results, predicted interface shapes were almost agreed with measured data. However, predicted falling down velocity of the jet was lower than measured data. We considered causes of this underestimation and improved the method and simulation conditions to resolve this problem.

Development of Numerical Simulation for Jet Breakup Behavior in Complicated Structure of BWR Lower Plenum: 2 — Flow Observation With Visualized Experimental Apparatus

2013 ◽  
Author(s):  
Ryusuke Saito ◽  
Yutaka Abe ◽  
Akiko Kaneko ◽  
Takayuki Suzuki ◽  
Hiroyuki Yoshida ◽  
...  
Keyword(s):  
Single Channel ◽  
Flow Channel ◽  
Type Model ◽  
Interface Tracking ◽  
Phase Flow ◽  
Complicated Structure ◽  
Support Plate ◽  
Jet Breakup ◽  
Experimental Apparatus ◽  
Multi Phase

In order to improve the safety of Boiling Water Reactor (BWR), it is required to know the behavior of the plant when an accident occurred as can be seen at Fukushima Daiichi nuclear power plant accident. Especially, it is important to estimate the behavior of molten core jet in the lower part of the containment vessel at severe accident. In the BWR lower plenum, the flow characteristics of molten core jet are affected by many complicated structures, such as control rod guide tubes (CRGT), instrument guide tubes and core support plate. However, it is difficult to evaluate these effects on molten core jet experimentally. Therefore, we considered that multi-phase computational fluid dynamics approach is the best way to estimate the effects on molten core jet by complicated structure. The objective of this study is to develop the evaluation method for the flow characteristic of molten core jet including the effects of the complicated structures in the lower plenum. So we are developing a simulation method to estimate the behavior of molten core jet falling down through the core support plate to the lower plenum of the BWR. The method has been developed based on interface tracking method code TPFIT (Two Phase Flow simulation code with Interface Tracking). To verify and validate the applicability of the developed method in detail, it is necessary to obtain the experimental data that can be compared with detailed numerical results by the TPFIT. Thus, in this study, we are carrying out experimental works by use of multi-phase flow visualization technique. For the experiment works, we constructed two experimental apparatuses, one is single-channel experimental apparatus and the other is multi-channel experimental apparatus. The single-channel experimental apparatus simply simulate single flow channel between four CRGTs. The multi-channel experimental apparatus is a 1/10 planar type model of a lower plenum of BWR. In the experiments, we will obtain the jet breakup behavior and surrounding velocity profiles of the jet by using LIF and PIV. In this paper, the outline of two-experimental apparatuses are shown. And the results of the single-channel experimental apparatus with/without modelled complicated structures are also shown. In the results, it was confirmed that the complicated flow channel affects the jet injection and breakup behavior. And it was also confirmed that the complicated structures restrain diffusion of fragments of the jet.

High Speed Imaging and Two-Phase Flow Patterns During Flow Boiling in a Single Microchannel

2008 ◽  
Author(s):  
Jacqueline Barber ◽  
Khellil Sefiane ◽  
David Brutin ◽  
Lounes Tadrist
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Pressure Sensors ◽  
Flow Patterns ◽  
Bubble Nucleation ◽  
Phase Flow ◽  
Vapour Bubble ◽  
Two Phase ◽  
Over Time

Boiling in microchannels remains elusive due to the lack of full understanding of the mechanisms involved. A powerful tool in achieving better comprehension of the mechanisms is detailed imaging and analysis of the two phase flow at a fundamental level. We induced boiling in a single microchannel geometry (hydraulic diameter 727 μm), using a refrigerant FC-72, to investigate several flow patterns. A transparent, metallic, conductive deposit has been developed on the exterior of rectangular microchannels, allowing simultaneous uniform heating and visualisation to be conducted. The data presented in this paper is for a particular case with a uniform heat flux of 4.26 kW/m2 applied to the microchannel and inlet liquid mass flowrate, held constant at 1.33×10−5 kg/s. In conjunction with obtaining high-speed images and videos, sensitive pressure sensors are used to record the pressure drop profiles across the microchannel over time. Bubble nucleation, growth and coalescence, as well as periodic slug flow, are observed in the test section. Phenomena are noted, such as the aspect ratio and Reynolds number of a vapour bubble, which are in turn correlated to the associated pressure drops over time. From analysis of our results, images and video sequences with the corresponding physical data obtained, it is possible to follow visually the nucleation and subsequent both ‘free’ and ‘confined’ growth of a vapour bubble over time.

Analysis of Transient Two-Phase Flow in Pressure Safety Valve Outlet Headers

2018 ◽  
Author(s):  
Maral Taghva ◽  
Lars Damkilde
Keyword(s):  
Steady State ◽  
Shock Waves ◽  
High Speed ◽  
Two Phase Flow ◽  
Safety Valve ◽  
Strong Shock ◽  
Flow Property ◽  
Phase Flow ◽  
Transient Pressure ◽  
Two Phase

To protect a pressurized system from overpressure, one of the most established strategies is to install a Pressure Safety Valve (PSV). Therefore, the excess pressure of the system is relieved through a vent pipe when PSV opens. The vent pipe is also called “PSV Outlet Header”. After the process starts, a transient two-phase flow is formed inside the outlet header consisting of high speed pressurized gas interacting with existing static air. The high-speed jet compresses the static air towards the end tail of the pipe until it is discharged to the ambiance and eventually, the steady state is achieved. Here, this transient process is investigated both analytically and numerically using the method of characteristics. Riemann’s solvers and Godunov’s method are utilized to establish the solution. Propagation of shock waves and flow property alterations are clearly demonstrated throughout the simulations. The results show strong shock waves as well as high transient pressure take place inside the outlet header. This is particularly important since it indicates the significance of accounting for shock waves and transient pressure, in contrast to commonly accepted steady state calculations. More precisely, shock waves and transient pressure could lead to failure, if the pipe thickness is chosen only based on conventional steady state calculations.

The Research on Steering Fracture Numerical Simulation

2013 ◽  
Vol 734-737 ◽  
pp. 1488-1492
Author(s):  
Zhen Yu Liu ◽  
Li Hong Yao ◽  
Hu Zhen Wang ◽  
Cui Cui Ye
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Three Dimensional ◽  
Simulation Method ◽  
Production Performance ◽  
Phase Flow ◽  
Water Production ◽  
Two Phase ◽  
Fractured Well

The fractures after artificial steering fracturing appear in shades of curved surface. Aiming at the problem of steering fracture, in the paper, numerical simulation method under the condition of three-dimensional two-phase flow is presented based on finite element method. In this method, of steering fracture was achieved by adopting surface elements fractures and tetrahedron elements to describe formation. By numerical simulation, the change rule of oil and water production performance of steering fractures can be calculated, and then the steering fracture parameters can be optimized before fracturing. A new method was supplied for the numerical simulation of artificial fractured well.

scholarly journals Experimental Investigation of the Performance and Spray Characteristics of a Supersonic Two-Phase Flow Ejector with Different Structures

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1166 ◽  
Author(s):  
Shizhen Li ◽  
Wei Li ◽  
Yanjun Liu ◽  
Chen Ji ◽  
Jingzhi Zhang
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Fire Suppression ◽  
Cone Angle ◽  
Water Mist ◽  
Pulsation Period ◽  
Phase Flow ◽  
Two Phase ◽  
Half Cone ◽  
Half Cone Angle

A two-phase flow ejector is an important part of a water mist fire suppression system, and these devices have become a popular research topic in recent years. This paper proposes a supersonic ejector that aims to improve the efficiency of water mist fire suppression systems. The effects of ejector geometric parameters on the entrainment ratio (ER) were explored. The effects of primary flow pressure (PP) on the mixing process and flow phenomena were studied by a high-speed camera. The experimental results show that the ER first increases and then decreases with increasing PP. ER increases with increasing ejector area ratio (AR). The PP corresponding to the maximum ER of ejectors with a different nozzle exit position (NXP) is 3.6 bar. The ejector with an NXP of +1 and AR of 6 demonstrate the best performance, and the ER of this ejector reaches 36.29. The spray half-cone angle of the ejector increases with increasing ER, reaching a maximum value of 7.07°. The unstable atomization half-cone angle is mainly due to a two-phase flow pulsating phenomenon. The pulsation period is 10 ms. In the present study, a general rule that provides a reference for ejector design and selection was obtained through experiments.

6. Inviscid instability of high speed two-phase flow

1998 ◽  
Vol 1 (1) ◽  
pp. 7-7 ◽  
Author(s):  
G. H. Schnerr ◽  
S. Adam
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Inviscid Instability
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