ICONE19-44166 Development of Prediction Technology of Two-Phase Flow Dynamics under Earthquake Acceleration (2) : Experimental Study on Flow Rate Fluctuation

2011 ◽  
Vol 2011.19 (0) ◽  
pp. _ICONE1944-_ICONE1944 ◽  
Author(s):  
Satoshi Okachi ◽  
Masaki Seto ◽  
Hideaki Monji ◽  
Akiko Kaneko ◽  
Yutaka Abe ◽  
...  
Keyword(s):  
Experimental Study ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Flow Dynamics ◽  
Phase Flow ◽  
Two Phase ◽  
Rate Fluctuation

Development of Prediction Technology of Two-Phase Flow Dynamics Under Earthquake Acceleration: 7 — Measurement of Velocity Profile Around Bubble Under Flow Rate Fluctuation

2013 ◽  
Author(s):  
Jun-ichi Takano ◽  
Satoshi Okachi ◽  
Hideaki Monji ◽  
Akiko Kaneko ◽  
Yutaka Abe ◽  
...  
Keyword(s):  
Flow Rate ◽  
Nuclear Reactor ◽  
Two Phase Flow ◽  
Bubbly Flow ◽  
Plug Flow ◽  
Flow Dynamics ◽  
Structural Vibration ◽  
Phase Flow ◽  
Two Phase ◽  
Rate Fluctuation

Earthquake is one of the most serious phenomena for safety of a nuclear reactor, especially in Japan. Therefore, nuclear reactors were contracted considering structural safety for a big earthquake. On the other hand, thermal-fluid behavior of the nuclear reactor is not fully confirmed under the earthquake. The behavior of nuclear reactor may be affected by the fluctuation of gas-liquid two-phase flow caused by the earthquake but not studied enough. For example, the bubble behavior under the fluctuation caused by the earthquake is not clear. In order to clear the two-phase flow behavior under the earthquake, it is studied systematically in the project of “Development of Prediction Technology of Two-Phase Flow Dynamics under Earthquake Acceleration”. In the project, bubbly or plug flow with flow rate fluctuation in a fixed horizontal pipe is studied experimentally. The bubbly or plug flow under the structural vibration but without the flow rate fluctuation is also studied. Here, the structural vibration done by using the pipe on the oscillation table. Moreover, the numerical code which can simulate the flows measured in the experiments is under development. In this paper, the result on the bubbly flow under the flow rate fluctuation is shown. The flow was bubbly flow and/or plug flow in a horizontal circular pipe. The working fluids were water and nitrogen gas. The water was driven by a pump and the flow rate fluctuation was given by a reciprocating piston attached to the main flow loop. In the study, the behavior of horizontal gas-liquid two-phase flow under the flow rate fluctuation is investigated with image processing and particle image velocimetry (PIV). As the result, the bubble’s deformation under the flow rate fluctuation was investigated by the image processing. The velocity profile around the bubble under flow rate fluctuation was measured with PIV. The velocity field around the deformed bubble showed the characteristic profile. Therefore, the velocity field changing with the flow rate fluctuation affected the bubble deformation.

scholarly journals Bubble behavior in horizontal two-phase flow under flow rate fluctuation

2014 ◽  
Vol 1 (4) ◽  
pp. TEP0019-TEP0019 ◽  
Author(s):  
Jun-ichi TAKANO ◽  
Hideaki MONJI ◽  
Akiko KANEKO ◽  
Yutaka ABE ◽  
Hiroyuki YOSHIDA ◽  
...  
Keyword(s):  
Flow Rate ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Bubble Behavior ◽  
Two Phase ◽  
Rate Fluctuation

Development of Prediction Technology of Two-Phase Flow Dynamics Under Earthquake Acceleration: (11) Bubble Motion Under the Flow Vibration

2014 ◽  
Author(s):  
Ryotaro Yokoyama ◽  
Jun-ichi Takano ◽  
Hideaki Monji ◽  
Akiko Kaneko ◽  
Yutaka Abe ◽  
...  
Keyword(s):  
Flow Rate ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubbly Flow ◽  
Plug Flow ◽  
Flow Simulation ◽  
Phase Flow ◽  
Bubble Behavior ◽  
Two Phase ◽  
Rate Fluctuation

Earthquake is one of the most serious phenomena for safety of a nuclear power plant. Therefore, nuclear reactors were contracted considering structural safety for a big earthquake. In a nuclear reactor, the gas-liquid two-phase flow is the one of primary factor of the property and bubbly or plug flow behavior is important issue to evaluate of safety. However, the influence of an earthquake vibration on the gas-liquid two-phase flow inside the nuclear power plant is not understood enough. For example, the bubbly flow behavior under the flow rate fluctuation caused by the earthquake acceleration is not clear. It is necessary to clear the two-phase flow behavior under the earthquake conditions. To develop the prediction technology of two-phase flow dynamics under the earthquake acceleration, the detailed two-phase flow simulation code with an advanced interface tracking method, TPFIT was expanded to the two-phase flow simulation under earthquake accelerating conditions. In the present study, the objective is to clarify the behavior of the gas-liquid two-phase flow under the earthquake conditions. Especially, the bubble behavior in the two-phase flow, a diameter, shape and velocity of bubbles which are expected to be influenced by the oscillation of the earthquake is investigated. In this experiment, the flow was bubbly flow and/or plug flow in a horizontal circular pipe. The working fluids were water and nitrogen gas. The nitrogen gas from gas cylinder was injected into the water through a nozzle and bubbly flow was generated at a mixer. The water was driven by a pump and the flow rate fluctuation was given by a reciprocating piston attached to the main flow loop. Main frequency of earthquakes is generally between 0.5Hz and 10Hz. Thus the frequency of the flow rate fluctuation in the experiment also was taken between 0.5Hz and 10Hz. The behavior of horizontal gas-liquid two-phase flow under the flow rate fluctuation was investigated by image processing using a high-speed video camera and PIV at test section. The pressure sensors were installed at the inlet of the mixer and the outlet of the test section. As the result, the bubble behavior mechanism under the flow rate fluctuation was obtained. In addition, the acceleration of a bubble and the pressure gradient in the pipe was synchronized under all frequency conditions. The prediction results by TPFIT were compared with the experimental results. They show good agreement on the flow field around a bubble and the bubble behavior.

Development of Prediction Technology of Two-Phase Flow Dynamics Under Earthquake Acceleration — (4) Measurement of Bubble Deformation Near Wall Under Flow Rate Fluctuation

2012 ◽  
Author(s):  
Satoshi Okachi ◽  
Masaki Seto ◽  
Hideaki Monji ◽  
Akiko Kaneko ◽  
Yutaka Abe ◽  
...  
Keyword(s):  
Flow Rate ◽  
Two Phase Flow ◽  
Pipe Wall ◽  
Flow Behavior ◽  
Plug Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Bubble Deformation ◽  
Rate Fluctuation

In order to clear the two-phase flow behavior under earthquake, a systematic study is done experimentally and numerically. The present study is one on the series of the study on two-phase flow under earthquake, and focuses on the flow rate fluctuation. The flow rate fluctuation was added to bubbly or plug flow in a horizontal pipe, and flow behavior was measured by PIV and image processing. The bubble deformation near the pipe wall was observed and the velocity field around the bubble was shown. The bubble coalescence was also observed under the flow rate fluctuation condition.

scholarly journals Experimental Study on Atomization Characteristics of Gas–Liquid Two-Phase Flow Nozzle and Its Dust Removal Effect

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 565
Author(s):  
Xueming Fang ◽  
Bingyou Jiang ◽  
Liang Yuan ◽  
Yuxiang Liang ◽  
Bo Ren ◽  
...  
Keyword(s):  
Experimental Study ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Respirable Dust ◽  
Phase Flow ◽  
Capture Effect ◽  
Two Phase ◽  
Ambient Humidity ◽  
Working Surface ◽  
Atomization Characteristics

An experimental study on the flow rate and atomization characteristics of a new gas–liquid two-phase flow nozzle was carried out to use high-concentration respirable dust in the workplace of high-efficiency sedimentation coal production based on the gas–liquid two-phase flow nozzle technology. The simulation roadway of dust fall in large coal mines was constructed, and the respirable rock dust produced by fully mechanized mining surfaces was chosen as the research object. The effects of humidity on the capture effect of respirable rock dust were analyzed in the experimental study. The results demonstrated that: (1) the distribution range of the particle size of fogdrops declines with the reduction in fogdrops D50, D[3,2] and D[4,3], which are produced by gas–liquid two-phase flow nozzles. (2) The initial ambient humidity in the simulated roadway was 64.8% RH. After the gas–liquid two-phase flow spray was started, the ambient humidity was elevated by 23.2 to 23.5% RH within 840s and tended to be stable and no longer grew after reaching 88.0–88.3% RH. The initial growth rate of the ambient humidity in the simulated roadway was high, and then was gradually slowed down. (3) Humidity is an important factor influencing the collection of respirable dust. The humidity at 10.0 m leeward of the dust-producing point was increased by 19.6% RH, and the sedimentation rate of respirable dust was increased by 6.73%; the two growth rates were 13.1% RH and 9.90% at 20.0 m; 16.4% RH and 15.42% at 30.0 m; 18.4% RH and 11.20% at 40.0 m. In practical applications of the gas–liquid two-phase flow nozzle in coal mining activities, attention shall be paid to not only the influences of its atomization characteristics on the capture effect of respirable dust but also the influences of the flow rate of the nozzle on the humidity of the working surface. Appropriate gas and water supply pressures shall be chosen according to the space and respirable dust concentration on the working surface to realize a better dust removal effect.

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