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.

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 Correction to Flow Rate Profile Interpretation for a Two-Phase Flow in Multistage Fractured Horizontal Wells by Inversion of DTS Data

ACS Omega ◽  
2020 ◽  
Vol 5 (41) ◽  
pp. 26955-26955
Author(s):  
Hongwen Luo ◽  
Beibei Jiang ◽  
Haitao Li ◽  
Ying Li ◽  
Zhangxin Chen
Keyword(s):  
Flow Rate ◽  
Two Phase Flow ◽  
Horizontal Wells ◽  
Phase Flow ◽  
Two Phase ◽  
Fractured Horizontal Wells ◽  
Rate Profile

Research on Two-Phase Flow Instability in Evaporator of Refrigeration System

2010 ◽  
Author(s):  
Nan Liang ◽  
Changqing Tian ◽  
Shuangquan Shao
Keyword(s):  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Density Wave ◽  
Phase Flow ◽  
Constant Mass ◽  
Refrigeration System ◽  
Two Phase

As one kind of fluid machinery related to the two-phase flow, the refrigeration system encounters more problems of instability. It is essential to ensure the stability of the refrigeration systems for the operation and efficiency. This paper presents the experimental investigation on the static and dynamic instability in an evaporator of refrigeration system. The static instability experiments showed that the oscillatory period and swing of the mixture-vapor transition point by observation with a camera through the transparent quartz glass tube at the outlet of the evaporator. The pressure drop versus mass flow rate curves of refrigerant two phase flow in the evaporator were obtained with a negative slope region in addition to two positive slope regions, thus making the flow rate a multi-valued function of the pressure drop. For dynamic instabilities in the evaporation process, three types of oscillations (density wave type, pressure drop type and thermal type) were observed at different mass flow rates and heat fluxes, which can be represented in the pressure drop versus mass flow rate curves. For the dynamic instabilities, density wave oscillations happen when the heat flux is high with the constant mass flow rate. Thermal oscillations happen when the heat flux is correspondingly low with constant mass flow rate. Though the refrigeration system do not have special tank, the accumulator and receiver provide enough compressible volume to induce the pressure drop oscillations. The representation and characteristic of each oscillation type were also analyzed in the paper.

Experimental, Numerical, and Statistical Investigation of Two Phase Flow in a Cylindrical Perforation Tunnel

2021 ◽  
Author(s):  
Ekhwaiter Abobaker ◽  
Abadelhalim Elsanoose ◽  
Mohammad Azizur Rahman ◽  
Faisal Khan ◽  
Amer Aborig ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Steady State ◽  
Statistical Analysis ◽  
Flow Rate ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Gas Flow Rate ◽  
Two Phase ◽  
Flow Through

Abstract Perforation is the final stage in well completion that helps to connect reservoir formations to wellbores during hydrocarbon production. The drilling perforation technique maximizes the reservoir productivity index by minimizing damage. This can be best accomplished by attaining a better understanding of fluid flows that occur in the near-wellbore region during oil and gas operations. The present work aims to enhance oil recovery by modelling a two-phase flow through the near-wellbore region, thereby expanding industry knowledge about well performance. An experimental procedure was conducted to investigate the behavior of two-phase flow through a cylindrical perforation tunnel. Statistical analysis was coupled with numerical simulation to expand the investigation of fluid flow in the near-wellbore region that cannot be obtained experimentally. The statistical analysis investigated the effect of several parameters, including the liquid and gas flow rate, liquid viscosity, permeability, and porosity, on the injection build-up pressure and the time needed to reach a steady-state flow condition. Design-Expert® Design of Experiments (DoE) software was used to determine the numerical simulation runs using the ANOVA analysis with a Box-Behnken Design (BBD) model and ANSYS-FLUENT was used to analyses the numerical simulation of the porous media tunnel by applying the volume of fluid method (VOF). The experimental data were validated to the numerical results, and the comparison of results was in good agreement. The numerical and statistical analysis demonstrated each investigated parameter’s effect. The permeability, flow rate, and viscosity of the liquid significantly affect the injection pressure build-up profile, and porosity and gas flow rate substantially affect the time required to attain steady-state conditions. In addition, two correlations obtained from the statistical analysis can be used to predict the injection build-up pressure and the required time to reach steady state for different scenarios. This work will contribute to the clarification and understanding of the behavior of multiphase flow in the near-wellbore region.

scholarly journals Numerical Study of Bubble Rising and Coalescence Characteristics under Flow Pulsation Based on Particle Method

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Ronghua Chen ◽  
Minghao Zhang ◽  
Kailun Guo ◽  
Dawei Zhao ◽  
Wenxi Tian ◽  
...  
Keyword(s):  
Flow Rate ◽  
Two Phase Flow ◽  
Flow Instability ◽  
Numerical Study ◽  
Phase Flow ◽  
Flow Pulsation ◽  
Two Phase ◽  
Inlet Flow ◽  
Inlet Flow Rate ◽  
Bubble Rising

Two-phase flow instability may occur in nuclear reactor systems, which is often accompanied by periodic fluctuation in fluid flow rate. In this study, bubble rising and coalescence characteristics under inlet flow pulsation condition are analyzed based on the MPS-MAFL method. To begin with, the single bubble rising behavior under flow pulsation condition was simulated. The simulation results show that the bubble shape and rising velocity fluctuate periodically as same as the inlet flow rate. Additionally, the bubble pairs’ coalescence behavior under flow pulsation condition was simulated and compared with static condition results. It is found that the coalescence time of bubble pairs slightly increased under the pulsation condition, and then the bubbles will continue to pulsate with almost the same period as the inlet flow rate after coalescence. In view of these facts, this study could offer theory support and method basis to a better understanding of the two-phase flow configuration under flow pulsation condition.

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