Influence of a Flow Obstacle on Boiling Two-Phase Flow

2011 ◽  
Author(s):  
Takeyuki Ami ◽  
Hisashi Umekawa ◽  
Mamoru Ozawa
Keyword(s):  
Liquid Film ◽  
Test Section ◽  
Fuel Cycle ◽  
Experimental Results ◽  
Axial Position ◽  
Two Phase ◽  
Convective Boiling ◽  
Water Reactor ◽  
Calculation Results ◽  
Liquid Film Flow

The spacer of Boiling Water Reactor (BWR) becomes the flow obstacle. Moreover the clearance between fuel rods of the innovative Water Reactor for Flexible fuel cycle (FLWR) becomes very narrow. Thus understanding of the thermal-fluid characteristics in the boiling channel equipped with the flow obstacle becomes more important. In this study, to clarify the flow obstacle effect, the experimental investigation was conducted with the forced convective boiling system. The test section was 8 mm in inner diameter, and the rod-type flow obstacle, which had 3.6 mm in diameter and 20 mm in length, was installed. The blockage ratio β = 20.3% which was the similar value of the present BWR reactor. The heating length LT was taken three different lengths, LT = 810, 840 and 900 mm. As the experimental results, the CHF was increased by the installing of the flow obstacle, and it was strongly influenced by the axial position of the flow obstacle. In the most of the case, the liquid film dryout was detected at the exit of the test section, while the CHF was observed at the upstream of the flow obstacle in the case of the LT = 810 mm. The calculation results of the liquid film flow model have shown a good agreement with these experimental results by using the presented influence length of the flow obstacle.

Development of Analytical Procedures of Two-Phase Flow in Tight-Lattice Fuel Bundles for Innovative Water Reactor for Flexible Fuel Cycle

2008 ◽  
Vol 164 (1) ◽  
pp. 45-54 ◽  
Author(s):  
Hiroyuki Yoshida ◽  
Akira Ohnuki ◽  
Takeharu Misawa ◽  
Kazuyuki Takase ◽  
Hajime Akimoto
Keyword(s):  
Two Phase Flow ◽  
Fuel Cycle ◽  
Phase Flow ◽  
Two Phase ◽  
Water Reactor ◽  
Analytical Procedures ◽  
Tight Lattice

Development of Prediction Technology of Two-Phase Flow Dynamics Under Earthquake Acceleration: (12) Bubble Motion Along the Flow in Structure Vibration

2014 ◽  
Author(s):  
Yuki Kato ◽  
Rie Arai ◽  
Akiko Kaneko ◽  
Hideaki Monji ◽  
Yutaka Abe ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Velocity Field ◽  
Test Section ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubbly Flow ◽  
Experimental Results ◽  
Phase Flow ◽  
Bubble Motion ◽  
Two Phase

In a nuclear power plant, one of the important issues is an evaluation of the safety of the reactor core and its pipes when an earthquake occurs. Many researchers have conducted studies on constructions of plants. Consequently, there is some knowledge about earthquake-resisting designs. However the influence of an earthquake vibration on thermal fluid inside a nuclear reactor plant is not fully understood. Especially, there is little knowledge how coolant in a core response when large earthquake acceleration is added. Some studies about the response of fluid to the vibration were carried out. And it is supposed that the void fraction and/or the power of core are fluctuated with the oscillation by the experiments and numerical analysis. However the detailed mechanism about a kinetic response of gas and liquid phases is not enough investigated, therefore the aim of this study is to clarify the influence of vibration of construction on bubbly flow behavior. In order to investigate the influence of vibration of construction on bubbly flow behavior, we visualized bubbly flow in pipeline on which sine wave was applied. In a test section, bubbly flow was produced by injecting gas into liquid flow through a horizontal circular pipe. In order to vibrate the test section, an oscillating table was used. The frequency and acceleration of vibration added from the oscillating table was from 1.0 Hz to 10 Hz and . 0.4 G (1 G=9.8 m/s2) at each frequency. The test section and a high speed video camera were fixed on the oscillating table. Thus the relative velocity between the camera and the test section was ignored. PIV measurement was also conducted to investigate interaction between bubble motion and surround in flow structure. Liquid pressure was also measured at upstream and downstream of the test section. The effects of oscillation on bubbly flow were quantitatively evaluated by these pressure measurements and the velocity field. In the results, it was observed that the difference of bubble motion by changing oscillation frequency. Moreover it was suggested that the bubble deformation is correlated with the fluctuation of liquid velocity field around the bubble and the pressure gradient in the flow area. In addition, these experimental results were compared with numerical simulation by a detailed two-phase flow simulation code with an advanced interface tracking method, TPFIT. Numerical simulation was qualitatively agreed with experimental results.

An Investigation of the Liquid Distribution in Annular-Mist Flow

1970 ◽  
Vol 92 (4) ◽  
pp. 651-658 ◽  
Author(s):  
J. T. Pogson ◽  
J. H. Roberts ◽  
P. J. Waibler
Keyword(s):  
Heat Transfer ◽  
Film Thickness ◽  
Liquid Film ◽  
Flow Rate ◽  
Droplet Size Distribution ◽  
Correlation Equation ◽  
Vapor Flow ◽  
Two Phase ◽  
Liquid Distribution ◽  
Liquid Film Flow

The results of an experimental investigation of the average liquid film thickness are presented for vertical upward annular-mist two-phase flow, with and without heat transfer. The effects on the film thickness for variations in vapor flow rate, liquid flow rate, vapor density, and heat transfer are described. A correlation equation is presented for the local time-averaged thickness and for the droplet size distribution. In addition, an equation is given for the liquid film flow rate as a function of the average film thickness.

Turbulence Structures in Horizontal Two-Phase Flows Under Counter-Current Conditions

2006 ◽  
Author(s):  
Thomas D. Sta¨bler ◽  
Leonhard Meyer ◽  
Thomas Schulenberg ◽  
Eckart Laurien
Keyword(s):  
Liquid Film ◽  
Test Section ◽  
Gas Flow ◽  
Second Phase ◽  
Two Phase Flows ◽  
Two Phase ◽  
Flow Rates ◽  
Local Measurements ◽  
Counter Current ◽  
Film Flows

In order to improve the multi-dimensional numerical simulation of horizontal two-phase flows, the knowledge of local turbulent quantities is of great importance. In horizontal stratified flows, the denser (first) phase flows as a film beneath the other (second) phase. Under counter-current conditions, the second phase flows into the opposite direction of the first phase. In the present investigations a liquid film flows counter-currently to a gas flow. According to the flow rates of both phases, different flow regimes set in. In supercritical flows (Fr>1), the height of the liquid film increases in flow direction, while it decreases in subcritical flows (Fr<1). For sufficiently high gas flow rates the upper part of the liquid film flows into direction of the gas flow, while the lower part still flows into its initial direction opposite to the gas flow. Only a reduced amount of water reaches the end of the test section. This flow regime is referred to as partially reversed flow. The presented local measurements provide not only the mean and rms-velocities of the liquid film, but also the corresponding Reynolds stresses. Local measurements are carried out at two different positions along the test section for various boundary conditions. Furthermore, the liquid injection height has been varied. The kinematic and turbulent structures of the different flow patterns are presented and compared.

Study on Characteristics of Liquid Film Flow and Mass Transfer in Annular Two-Phase Flow

2017 ◽  
Vol 2017.22 (0) ◽  
pp. F112
Author(s):  
Takayuki YAMAGATA ◽  
Minoru KOMATSU ◽  
Nobuyuki FUJISAWA ◽  
Fumio INADA
Keyword(s):  
Mass Transfer ◽  
Liquid Film ◽  
Film Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Liquid Film Flow

Analysis of Axial Meniscus Jump-Like Transition in Rectangular Microgrooves

2010 ◽  
Author(s):  
Chaohong Guo ◽  
Xuegong Hu ◽  
Tao Wang ◽  
Dawei Tang
Keyword(s):  
Liquid Film ◽  
Liquid Velocity ◽  
Dead Zone ◽  
Axial Flow ◽  
Step Change ◽  
Experimental Results ◽  
Cross Sectional ◽  
Corner Flow ◽  
Calculation Results ◽  
Flow Stage

The meniscus receding process was studied for the axial steady flow in open rectangular microgrooves based on experimental results. Experimental results show that the liquid film recedes remarkably as a cubic trendline from the accommodation stage to the bottom corner-flow stage, but the dead zone and the step change don’t exist. The receding process of the liquid film between the accommodation stage and the bottom corner-flow stage is named jump-like transition in the paper. Characteristics of the axial flow in rectangular microgrooves were theoretically analyzed considering the meniscus receding performance in the jump-like transition, calculation results show that radius of the meniscus curvature decreases along the groove axis, which provides drive for the axial flow; the liquid cross sectional area and the liquid height decrease evidently at the stage of the jump-like transition; the liquid velocity increases along the axis, and increases promptly at the transition stage and the corner flow stage.

Hydrodynamics and mass transfer in turbulent liquid film flow involving the inlet portion

1981 ◽  
Vol 46 (2) ◽  
pp. 467-477 ◽  
Author(s):  
L. P. Kholpanov ◽  
V. A. Malyusov ◽  
N. M. Zhavoronkov
Keyword(s):  
Mass Transfer ◽  
Liquid Film ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Film Flow ◽  
Experimental Results ◽  
Inlet Section ◽  
Liquid Film Flow

Relationship for mass transfer coefficient in turbulent liquid film flow involving the inlet section have been derived theoretically. It was found that previously published experimental results were well explained by this theory.

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