Two-Phase Flow-Induced Forces on Piping in Vertical Upward Flow: Excitation Mechanisms and Correlation Models

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
M. Giraudeau ◽  
N. W. Mureithi ◽  
M. J. Pettigrew
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Low Frequency ◽  
Flow Patterns ◽  
Large Momentum ◽  
Phase Flow ◽  
Upward Flow ◽  
Two Phase ◽  
Correlation Models ◽  
Wide Range

Momentum variation in two-phase flow generates significant low frequency forces, capable of producing unwanted and destructive vibrations in nuclear or petroleum industries. Two-phase flow-induced forces in piping were previously studied over a range of diameters from 6 mm to 70 mm in different piping element geometries, such as elbows, U-bends, and tees. Dimensionless models were then developed to estimate the rms forces and generate vibration excitation force spectra. It was found that slug flow generates the largest forces due to the large momentum variation between Taylor bubbles and slugs. The present study was conducted with a 52 mm diameter U-bend tube carrying a vertical upward flow. Two-phase flow-induced forces were measured. In addition, two-phase flow parameters, such as the local void fraction, bubble size and velocity, and slug frequency were studied to understand the relationship between the force spectra and the two-phase flow patterns. A new two-phase flow pattern map, based on existing transition models and validated using our own local void fraction measurements and force spectra, is proposed. This paper also presents a comparison of the present dimensionless forces with those of previous studies, thus covers a wide range of geometries and Weber numbers. Finally, a dimensionless spectrum is proposed to correlate forces with large momentum variations observed for certain flow patterns.

Flow Characteristics of Adiabatic Gas-Liquid Two-Phase Flow in a Horizontal Flat Rectangular Microchannel

2011 ◽  
Author(s):  
Hideo Ide ◽  
Kentaro Satonaka ◽  
Tohru Fukano
Keyword(s):  
Void Fraction ◽  
Slug Flow ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Phase Flow ◽  
Similar Data ◽  
Two Phase ◽  
The Mean

Experiments were performed to obtain, analyze and clarify the mean void fraction, the mean liquid holdup, and the liquid slug velocity and the air-water two-phase flow patterns in horizontal rectangular microchannels, with the dimensions equal to 1.0 mm width × 0.1 mm depth, and 1.0 mm width × 0.2 mm depth, respectively. The flow patterns such as bubble flow, slug flow and annular flow were observed. The microchannel data showed similar data patterns compared to those in minichannels with the width of 1∼10mm and the depth of 1mm which we had previously reported on. However, in a 1.0 × 0.1 mm microchannel, the mean holdup and the base film thickness in annular flow showed larger values because the effects of liquid viscosity and surface tension on the holdup and void fraction dominate. The remarkable flow characteristics of rivulet flow and the flow with a partial dry out of the channel inner wall were observed in slug flow and annular flow patterns in the microchannel of 0.1 mm depth.

Experiment of Adiabatic Two-Phase Flow in an Annulus Under Low-Frequency Vibration

2012 ◽  
Author(s):  
Shao-Wen Chen ◽  
Caleb S. Brooks ◽  
Chris Macke ◽  
Takashi Hibiki ◽  
Mamoru Ishii ◽  
...  
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Low Frequency ◽  
Flow Regimes ◽  
Operating Conditions ◽  
Phase Flow ◽  
Two Phase ◽  
Specific Flow ◽  
Low Frequency Vibration ◽  
Fft Analysis

In order to investigate the possible effect of seismic vibration on two-phase flow dynamics and thermal-hydraulics of a nuclear reactor, experimental tests of adiabatic air-water two-phase flow under low-frequency vibration were carried out in this study. An eccentric cam vibration module operated at low motor speed (up to 390rpm) was attached to an annulus test section which was scaled down from a prototypic BWR fuel assembly sub-channel. The inner and outer diameters of the annulus are 19.1mm and 38.1mm, respectively. The two-phase flow operating conditions cover the ranges of 0.03≤<jg> ≤1.46m/s and 0.25≤<jf>≤1.00m/s and the vibration displacement ranges from ±0.8mm to ±22.2mm. Steady-state area-averaged instantaneous and time-averaged void fraction was recorded and analyzed in stationary and vibration experiments. A neural network flow regime identification technique and fast Fourier transformation (FFT) analysis were introduced to analyze the flow regimes and void signals under stationary and vibration conditions. Experimental results reveal possible changes in flow regimes under specific flow and vibration conditions. In addition, the instantaneous void fraction signals were affected and shown by FFT analysis. Possible reasons for the changes include the applied high acceleration and/or induced resonance at certain ports under the specific flow and vibration conditions.

Evaluation of Void Fraction Correlations for the Statistical and Numerical Analysis of Two-Phase Flows Inside Producing Geothermal Wells

2008 ◽  
Author(s):  
A. A´lvarez del Castillo ◽  
E. Santoyo ◽  
O. Garci´a-Valladares ◽  
P. Sa´nchez-Upton
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Temperature Gradients ◽  
Production Performance ◽  
Phase Flow ◽  
Two Phase ◽  
Precise Knowledge ◽  
Geothermal Wells ◽  
Gas Void Fraction

The modeling of heat and fluid flow inside two-phase geothermal wells is a vital task required for the study of the production performance. Gas void fraction is one of the crucial parameters required for a better prediction of pressure and temperature gradients in two-phase geothermal wells. This parameter affects the correct matching between simulated and measured data. Modeling of two-phase flow inside wells is complex because two phases exist concurrently (exhibiting various flow patterns that depend on their relative concentrations, the pipe geometry, and the mass flowrate). A reliable modeling requires the precise knowledge of the two-phase flow patterns (including their transitions and some flow parameters). In this work, ten empirical correlations were used to estimate the gas void fraction in vertical-inclined pipes, and to evaluate their effect on the prediction of two-phase flow characteristics of some Mexican geothermal wells. High quality downhole pressure/ temperature logs collected from four producing geothermal wells were studied [Los Azufres, Mich. (Az-18); Los Humeros, Pue. (H-1), and Cerro Prieto, B.C. (M-90 and M-201)]. The pressure/ temperature gradients were simulated using an improved version of the wellbore simulator GEOPOZO, and the gas void fraction correlations. The simulated results were statistically compared with measured field data.

Development of a Capacitance Based Void Fraction Sensor for Two-Phase Flow Measurements

2013 ◽  
Author(s):  
Rodward L. Hewlin ◽  
John P. Kizito
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Full Range ◽  
Working Fluid ◽  
Phase Flow ◽  
Calibration Data ◽  
Two Phase ◽  
Flow Measurements ◽  
Static Calibration ◽  
Wide Range

The aim of this paper was to develop a capacitance based sensor capable of measuring void fraction in a continuous two-phase flow field. The design methodology and operation of the capacitance based void fraction sensor is discussed. Two designs of capacitance void fraction sensors were developed and tested. Some of the problems associated with the first were identified and a new sensor electrode configuration was developed which presented a more sensitive and repeatable response. Data was collected covering a wide range of void fraction measurements ranging from 0 to 1 for water as the working fluid. Calibration of the sensor required that the air gap or void capacitance (dry signal) be measured followed by an increase in liquid levels (wet signal) to obtain a range of void fraction measurements for static calibration. The static calibration data obtained was nonlinear for the full range of void fraction measurements for water. This paper covers the design requirements, calibration procedure and static calibration data obtained for the developed sensor, and dynamic void fraction data measurements. The sensor was tested in both a horizontal and vertical orientation and proved to be orientation insensitive. The experimental results are promising for water and verify successful operation for measuring void fraction in continuous two-phase flows.

scholarly journals Flow Patterns Transition Law of Oil-Water Two-Phase Flow under a Wide Range of Oil Phase Viscosity Condition

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Wei Wang ◽  
Wei Cheng ◽  
Kai Li ◽  
Chen Lou ◽  
Jing Gong
Keyword(s):  
Two Phase Flow ◽  
Stratified Flow ◽  
High Viscosity ◽  
Flow Patterns ◽  
Intermittent Flow ◽  
Neutral Stability ◽  
Phase Flow ◽  
Two Phase ◽  
Wide Range ◽  
Oil Water

A systematic work on the prediction of flow patterns transition of the oil-water two-phase flows is carried out under a wide range of oil phase viscosities, where four main flow regimes are considered including stratified, dispersed, core-annular, and intermittent flow. For oil with a relatively low viscosity, VKH criterion is considered for the stability of stratified flow, and critical drop size model is distinguished for the transition of o/w and w/o dispersed flow. For oil with a high viscousity, boundaries of core-annular flow are based on criteria proposed by Bannwart and Strazza et al. and neutral stability law ignoring that the velocity of the viscous phase is introduced for stratified flow. Comparisons between predictions and quantities of available data in both low and high viscosity oil-water flow from literatures show a good agreement. The framework provides extensive information about flow patterns transition of oil-water two-phase flow for industrial application.

Experimental Study of Adiabatic Two-Phase Flow in an Annular Channel Under Low-Frequency Vibration

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Shao-Wen Chen ◽  
Takashi Hibiki ◽  
Mamoru Ishii ◽  
Michitsugu Mori ◽  
Fumitoshi Watanabe
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Low Frequency ◽  
Flow Regimes ◽  
Operating Conditions ◽  
Phase Flow ◽  
Two Phase ◽  
Specific Flow ◽  
Low Frequency Vibration ◽  
Fft Analysis

In order to investigate the possible effect of seismic vibration on two-phase flow dynamics and thermal-hydraulics of a nuclear reactor, experimental tests of adiabatic air-water two-phase flow under low-frequency vibration were carried out in this study. An eccentric cam vibration module operated at low motor speed (up to 390 rpm) was attached to an annulus test section which was scaled down from a prototypic boiling water reactor (BWR) fuel assembly subchannel. The inner and outer diameters of the annulus are 19.1 mm and 38.1 mm, respectively. The two-phase flow operating conditions cover the ranges of 0.03 m/s ≤ 〈jg〉 ≤ 1.46 m/s and 0.25 m/s ≤ 〈jf〉 ≤ 1.00 m/s and the vibration displacement ranges from ±0.8 mm to ±22.2 mm. Steady-state area-averaged instantaneous and time-averaged void fraction were recorded and analyzed in stationary and vibration experiments. A neural network flow regime identification technique and fast Fourier transformation (FFT) analysis were introduced to analyze the flow regimes and void signals under stationary and vibration conditions. Experimental results reveal possible changes in flow regimes under specific flow and vibration conditions. In addition, the instantaneous void fraction signals were affected and shown by FFT analysis. Possible reasons for the changes include the applied high acceleration and induced void/flow structure changes at certain ports under the specific flow and vibration conditions.

Verification of Using a Single Void Fraction Sensor to Identify Two-Phase Flow Patterns

1991 ◽  
Vol 95 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Y. W. Wang ◽  
B. S. Pei ◽  
W. K. Lin
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase

An Advanced Ultrasonic Technique for Flow and Void Fraction Measurements of Two-Phase Flow

2004 ◽  
Author(s):  
J. L. H. Faccini ◽  
J. Su ◽  
G. D. Harvel ◽  
J. S. Chang
Keyword(s):  
Void Fraction ◽  
Test Section ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Ultrasonic Flowmeter ◽  
Time Averaging ◽  
Phase Flow ◽  
Ultrasonic Technique ◽  
Two Phase ◽  
Pulse Echo

In this paper, we present a hybrid type contrapropagating transmission ultrasonic technique (CPTU) for flow and time averaging ultrasonic transmission intensity void fraction measurements (TATIU) of air-water two-phase flow, which is tested in the new two-phase flow test section mounted recently onto an existing single phase flow rig at the Nuclear Engineering Institute (IEN)/CNEN, Brazil. The circular pipe test section is made of 51.2 mm stainless steel, followed by a transparent extruded acrylic pipe aimed at flow visualization. The two-phase flow rig operates in several flow regimes: bubbly, smooth stratified, wavy stratified and slug flow. The observed flow patterns are compared with the Mandhane et al.’s experimental and Lightstone et al.’s numerical flow regime map for horizontal two phase flows. These flow patterns will be identified by time averaging transmission intensity ultrasonic techniques which have been developed to meet this particular application. A contrapropagating transmission ultrasonic flowmeter is used to measure the flow rate of liquid phase. A pulse-echo TATIU ultrasonic technique used to measure the void fraction of the horizontal test section assembling at IEN is presented. Other flow parameters can be deduced by processing the signals obtained by the CPTU ultrasonic flowmeter and the pulse-echo generator-receiver (TATIU system).

Correlation between Void Fraction and Two-Phase Flow Pattern Air-Water with Low Viscosity in Mini Channel with Slope 30 Degrees

2020 ◽  
Vol 846 ◽  
pp. 289-295
Author(s):  
Sukamta ◽  
Sudarja
Keyword(s):  
Void Fraction ◽  
High Speed ◽  
Two Phase Flow ◽  
Fluid Velocity ◽  
Flow Patterns ◽  
Superficial Velocity ◽  
Working Fluid ◽  
Phase Flow ◽  
Two Phase ◽  
Void Fractions

Two-phase flow has been used in so many industrial processes, such as boilers, reactors, heat exchangers, geothermal and others. Some parameters which need to be studied include flow patterns, void fractions, and pressure changes. Research on void fractions aims to determine the composition of the gas and liquid phases that will affect the nature and value of the flow property. The purpose of this study is to find out the characteristics of the void fraction of various patterns that occurs and to determine the characteristics of the velocity, length, and frequency of bubbly and plug. Data acquisition was used to convert the data from analog to digital so that it can be recorded, stored, processed, and analyzed. High-speed camera Nikon type J4 was used to record the flow. The condition of the study was adiabatic with variation of superficial gas velocity (JG), superficial fluid velocity (JL), and also working fluid. To determine the void fraction by using the digital image processing method. The results of the study found that the flow patterns which occurred in this study were bubbly, plug, annular, slug-annular and churn flows. It also showed that the void fraction value is determined by the superficial velocity of the liquid and air. The higher the superficial velocity of the air, the lower the void fraction value.

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