Random Forces Resulting From Internal Two-Phase Flow on Bends and Tees

2006 ◽  
Author(s):  
E. de Langre ◽  
J. L. Riverin ◽  
M. J. Pettigrew
Keyword(s):  
Two Phase Flow ◽  
Experimental Results ◽  
Time Dependent ◽  
Phase Flow ◽  
Water Mixture ◽  
Dimensionless Form ◽  
Two Phase ◽  
Practical Applications ◽  
Random Forces

The time dependent forces resulting from a two-phase air-water mixture flowing in an elbow and a tee are measured. Their magnitudes as well as their spectral contents are analyzed. Comparison is made with previous experimental results on similar systems. For practical applications a dimensionless form is proposed to relate the characteristics of these forces to the parameters defining the flow and the geometry of the piping.

New Correlation for Two-Phase Flow in 90 Degree Horizontal Elbows

2010 ◽  
Author(s):  
Florencio Sanchez-Silva ◽  
Ignacio Carvajal-Mariscal ◽  
Rene Tolentino-Eslava
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Experimental Results ◽  
Galvanized Steel ◽  
Average Error ◽  
Phase Flow ◽  
Volumetric Fraction ◽  
Dean Number ◽  
Two Phase ◽  
Flow Pressure

The comparison of experimental data and results obtained from four global models — homogeneous, Dukler, Martinelli and Chisholm, used to evaluate the two-phase flow pressure drop in circular 90° horizontal elbows — is presented in this paper. An experimental investigation was carried out using three galvanized steel 90° horizontal elbows (E1, E2, E3) with internal diameters of 26.5, 41.2 and 52.5 mm, and curvature radii of 194.0, 264.0 and 326.6 mm, respectively. According to the experimental results, the model proposed by Chisholm best fitted them, presenting for each elbow an average error of E1 = 18.27%, E2 = 28.40% and E3 = 42.10%. Based on experimental results two correlations were developed. The first one is the classical Chisholm model modified to obtain better results in a wider range of conditions; it was adjusted by a dimensionless relationship which is a function of the homogeneous volumetric fraction and the Dean number. As a result, the predictions using modified Chisholm model were improved presenting an average error of 8.66%. The second developed correlation is based on the entire two-phase mass flow taken as liquid and adjusted by the homogeneous volumetric fraction ratio. The results show that this last correlation is easier and accurate than the adjusted Chisholm model, presenting an average error of 7.75%. Therefore, this correlation is recommended for two-phase pressure drop evaluation in horizontal elbows.

Boiling and Two-Phase Flow in Channels With Extremely Small Dimensions: Review of Japanese Research

2004 ◽  
Author(s):  
Haruhiko Ohta
Keyword(s):  
High Performance ◽  
Two Phase Flow ◽  
Waste Heat ◽  
Narrow Channel ◽  
Phase Flow ◽  
Parallel Plates ◽  
Two Phase ◽  
Practical Applications ◽  
Ideal System ◽  
Mini Channels

Researches concerning micro actuators utilizing vapor-liquid interfacial phenomena are extensively investigated to develop thermal devices applied to micro machines. On the other hand, the application of two-phase flow is useful for the removal of waste heat from the semiconductor chips with highly increased heat generation density to be integrated in notebook PCs. In the present paper, the latest Japanese research on boiling and two-phase flow in mini channels is reviewed covering those for the fundamental phenomena and practical applications. Boiling in a narrow channel between parallel plates is an ideal system for the development of the high-performance heat exchangers with extremely small sizes. The promising approaches to increasing the critical heat flux are introduced those by the present author to compensate the disadvantage inherent in this system.

Two-phase flow modelling for oxygen renewal estimation in vertical flow filter: luxury or necessity?

2009 ◽  
Vol 59 (12) ◽  
pp. 2311-2319 ◽  
Author(s):  
N. Forquet ◽  
A. Wanko ◽  
P. Molle ◽  
R. Mosé ◽  
A.-G. Sadowski
Keyword(s):  
Two Phase Flow ◽  
Experimental Results ◽  
Phase Flow ◽  
Vertical Flow ◽  
Air Entrapment ◽  
Two Phase ◽  
Sand Filters ◽  
Water Flows ◽  
Flow Modelling ◽  
Hydraulic Load

Scientists and practitioners exhibit an increasing interest on effluent transfer and degradation modelling in Vertical Flow Sand Filters (VFSF) and Vertical Flow Constructed Wetland (VFCW). Modelling software used to this purpose is mainly monophasic: in the unsaturated zone, only water flow is taken into account and air phase influence is assumed to be negligible. In hydrology, many studies have point out the limitations of this assumption in order to quantify air phase movement but little has been done in the modelling of vertical flow filter. Despite its complexity, two-phase flow modelling allows to overcome these difficulties. In this work, we describe the complex air and water flows in the particular case of vertical flow filter fed intermittently using both numerical and experimental results. Complete different behaviour is observed depending on ponding occurs or not. If it does, flow is clearly influenced by air entrapment which is responsible of a reduction of the infiltration speed and of the drainage of a part of the water kept at the interface between the sand and the drainage layer. Finally, we study the dependency of oxygen income by convection on hydraulic load and compare numerical results with experimental results obtained on oxygen consumption.

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.

Two-Phase Flow Heat and Mass Transfer Model Construction and Experiment Study of the Fuel Evaporation Progress

2012 ◽  
Vol 614-615 ◽  
pp. 174-180
Author(s):  
Bo Yun Liu ◽  
Jin Yun Pu ◽  
Xiang Lie Yi
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Two Phase Flow ◽  
Time Dependent ◽  
Transfer Model ◽  
Phase Flow ◽  
Two Phase ◽  
Dependent Behavior ◽  
Mass Evaporation ◽  
Hot Surface

As for the time-dependent behavior of the fuel heat and mass evaporation transfer progress on hot surface,consider the convective mass transfer and heat transfer, the liquid-gas two-phase flow of continuous heat transfer model was studied. By the dimensionless transform, the time-dependent behavior of the concentration distribution and the temperature field was obtained. The result of n-Heptanes evaporation transfer progress on hot surface experiment is consistent with the academic model.

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