Local Liquid Velocities in Horizontal, Annular Air/Water Flow

2003 ◽  
Author(s):  
Charles R. Kopplin
Keyword(s):  
Liquid Film ◽  
Water Flow ◽  
Measurement Method ◽  
Annular Flow ◽  
Current Data ◽  
Air Bubbles ◽  
Flow Modeling ◽  
Two Phase ◽  
Flow Rates ◽  
Film Distribution

A newly developed flow visualization method that utilizes a three color LED strobe has been used to study the axial and circumferential velocities of the liquid in horizontal, annular two-phase flow. This non-intrusive technique allows the tracking of naturally entertained air bubbles within the liquid film along the top, bottom, and sides of the tube. Sets of images have been obtained for multiple combinations of air and water flow rates ranging in quality from approximately 0.07 to 0.49. The bubble-tracking velocimetry measurement method is explained, and comparison of the current data with past results and their impact on annular flow modeling are discussed. The data do not support two of the four theories for liquid film distribution in annular, horizontal multiphase flow, while the two remaining theories cannot be directly examined using the three color LED strobe measurement technique.

Measurement of Liquid Film Thickness in Micro Tube Annular Flow

2010 ◽  
Author(s):  
Hiroshi Kanno ◽  
Youngbae Han ◽  
Yusuke Saito ◽  
Naoki Shikazono
Keyword(s):  
Heat Transfer ◽  
Film Thickness ◽  
Liquid Film ◽  
Annular Flow ◽  
Liquid Film Thickness ◽  
Phase Flow ◽  
Two Phase ◽  
Micro Scale ◽  
Film Model ◽  
Annular Film

Heat transfer in micro scale two-phase flow attracts large attention since it can achieve large heat transfer area per density. At high quality, annular flow becomes one of the major flow regimes in micro two-phase flow. Heat is transferred by evaporation or condensation of the liquid film, which are the dominant mechanisms of micro scale heat transfer. Therefore, liquid film thickness is one of the most important parameters in modeling the phenomena. In macro tubes, large numbers of researches have been conducted to investigate the liquid film thickness. However, in micro tubes, quantitative information for the annular liquid film thickness is still limited. In the present study, annular liquid film thickness is measured using a confocal method, which is used in the previous study [1, 2]. Glass tubes with inner diameters of 0.3, 0.5 and 1.0 mm are used. Degassed water and FC40 are used as working fluids, and the total mass flux is varied from G = 100 to 500 kg/m2s. Liquid film thickness is measured by laser confocal displacement meter (LCDM), and the liquid-gas interface profile is observed by a high-speed camera. Mean liquid film thickness is then plotted against quality for different flow rates and tube diameters. Mean thickness data is compared with the smooth annular film model of Revellin et al. [3]. Annular film model predictions overestimated the experimental values especially at low quality. It is considered that this overestimation is attributed to the disturbances caused by the interface ripples.

scholarly journals A Modern Approach to Analyzing the Flowing Pressures of a Two-Phase CBM and Water Column in Producing Wellbores

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Xinfu Liu ◽  
Chunhua Liu ◽  
Jianjun Wu
Keyword(s):  
Water Level ◽  
Water Column ◽  
Water Flow ◽  
Flow Rate ◽  
Two Phase ◽  
Modern Approach ◽  
Flow Rates ◽  
Bottom Hole ◽  
Column Pressure ◽  
Phase Column

A modern methodology is presented for the system analysis of flowing pressures in order to forecast the dynamic behavior and solve the forthcoming problems that emerge in two-phase coalbed methane (CBM) wellbores. The proposed methodology involves a numerical integration technique to calculate flowing pressures and pressure drops of CBM and water flow from the bottom hole to the well head. The methodology is validated against full-scale measured data in coalfields. The relationships developed match CBM reservoir behavior and wellbore conditions along the annulus with an overall accuracy of 1.13%. The computation of flowing pressures involves a liquid holdup and kinetic energy term with flow rate increments, a compressibility factor with depth increments, and a friction factor with Reynolds number. The flowing pressures of a two-phase column fully reflect the dynamic flowing performance due to the combined action of the water level, CBM, and water flow rates. The effect of CBM and water column pressures is more obvious than that of CBM column pressures. The pressure ratios of CBM and the water column to the bottom hole decline rapidly with the increase of the dynamic water level. CBM and water flow rates can be improved with increases in CBM and water column pressure for two-phase producing wellbores. The decrease of flowing pressures and increased increment of the pressure drop for the two-phase column are beneficial to CBM desorption and result in the increased CBM and water production. It will control the falling speed of the dynamic water level above CBM and the water column and enhance CBM reservoir productivity. The increases of CBM and water column pressure from 34.6 kPa to 922 kPa and the decreases of pressure in the bottom hole from 2.252 MPa to 1.328 MPa lead to the increases of the CBM flow rate from 3327 m3/d to 6721 m3/d.

Effect of spacer with mixing vane on liquid film for two-phase annular flow in a simulated BWR reactor fuel rod bundle channel

2019 ◽  
Vol 2019.72 (0) ◽  
pp. D32
Author(s):  
Kohshi MUTA ◽  
Hiroto TAZOE ◽  
Yudai HISATUGU ◽  
Yukihiro YONEMOTO ◽  
Akimaro Kawarhara
Keyword(s):  
Liquid Film ◽  
Annular Flow ◽  
Reactor Fuel ◽  
Two Phase ◽  
Fuel Rod ◽  
Rod Bundle

Liquid film properties in two-phase annular flow

1976 ◽  
Vol 31 (6) ◽  
pp. 481-486 ◽  
Author(s):  
G.R. Thwaites ◽  
N.N. Kulov ◽  
R.M. Nedderman
Keyword(s):  
Liquid Film ◽  
Annular Flow ◽  
Film Properties ◽  
Two Phase

The Effect of Surfactants on Vertical Air/Water Flow for Prevention of Liquid Loading

SPE Journal ◽  
2016 ◽  
Vol 21 (02) ◽  
pp. 488-500 ◽  
Author(s):  
A. T. van Nimwegen ◽  
L. M. Portela ◽  
R. A. Henkes
Keyword(s):  
Surface Tension ◽  
Pressure Gradient ◽  
Water Flow ◽  
Annular Flow ◽  
Surfactant Concentration ◽  
Gas Flow ◽  
Liquid Loading ◽  
Dynamic Surface ◽  
Flow Rates ◽  
Churn Flow

Summary From field experience in the gas industry, it is known that injecting surfactants at the bottom of a gas well can prevent liquid loading. To better understand how the selection of the surfactant influences the deliquification performance, laboratory experiments of air/water flow at atmospheric conditions were performed, in which two different surfactants (a pure surfactant, sodium dodecyl sulfate, and a commercial surfactant blend) were added to the water. In the experiments, a high-speed camera was used to visualize the flow, and pressure-gradient measurements were performed. Both surfactants increase the pressure gradient at high gas-flow rates and decrease the pressure gradient at low gas-flow rates. The minimum in the pressure gradient moves to lower gas-flow rates with increasing surfactant concentration. This is related to the transition between annular flow and churn flow, which is shifted to lower gas-flow rates because of the formation of an almost stagnant foam substrate at the wall of the pipe. At high surfactant concentration, it appears that the churn flow regime is no longer present at all and that there is a direct transition from annular flow to slug flow. The results also show that the critical micelle concentration, the equilibrium surface tension, the dynamic surface tension, and the surface elasticity are poor predictors of the effect of the surfactant on the flow.

Cross-Sectional Imaging of the Liquid Film in Horizontal Two-Phase Annular Flow

Volume 3 ◽  
2004 ◽  
Author(s):  
Daniel J. Rodri´guez ◽  
Timothy A. Shedd
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Liquid Flow ◽  
Annular Flow ◽  
Laser System ◽  
Excitation Wavelength ◽  
Two Phase ◽  
Cross Sectional ◽  
Annular Regime ◽  
The Waves

Planar laser induced fluorescence (PLIF) was applied to horizontal air/water two-phase annular flow in order to clearly image the liquid film and interfacial wave behavior at the top, side and bottom of the tube. The visualization section was fabricated from FEP, which has nearly the same refractive index as water at room temperature. This index-matched test section was used to allow imaging of the water to within approximately 10 microns of the 15.1 mm I.D. tube wall. A small amount of dye was added to the water with a peak excitation wavelength near that of a pulsed Nd:YAG laser (532 nm). The laser system generated an approximately 5 ns pulsed light sheet at 30 Hz. Images of the liquid film were captured using a digital video camera with a macro lens for a resolution of about 8.2 microns/pixel. Cross-sectional data at 68 annular flow conditions were obtained. The observations of the liquid film between waves indicated that the film thickness was relatively insensitive to both gas and liquid flow in the annular regime, confirming film thickness measurements reported elsewhere. In addition, the structure of waves changes significantly from wavy-annular, where peaked or cresting waves dominate, to fully annular, where the waves are much more turbulent and unstructured. The wave height decreases with increased gas flow and is relatively insensitive to increased liquid flow in the annular regime. The entrainment of gas in the liquid by the waves is very apparent from these images. Although the precise entrainment mechanisms are not entirely clear, a viable folding action mechanism is proposed. The visualization results will be discussed in relation to both conceptual and computational annular flow modeling.

scholarly journals Experimental and theoretical study of dryout in annular flow in small diameter channels

2011 ◽  
Vol 32 (1) ◽  
pp. 89-108 ◽  
Author(s):  
Dariusz Mikielewicz ◽  
Michał Gliński ◽  
Jan Wajs
Keyword(s):  
Experimental Data ◽  
Liquid Film ◽  
Annular Flow ◽  
Theoretical Study ◽  
Small Diameter ◽  
Infrared Camera ◽  
Equation Model ◽  
Internal Diameter ◽  
Two Phase ◽  
Liquid Film Dryout

Experimental and theoretical study of dryout in annular flow in small diameter channels In the paper the experimental analysis of dryout in small diameter channels is presented. The investigations were carried out in vertical pipes of internal diameter equal to 1.15 mm and 2.3 mm. Low-boiling point fluids such as SES36 and R123 were examined. The modern experimental techniques were applied to record liquid film dryout on the wall, among the others the infrared camera. On the basis of experimental data an empirical correlation for predictions of critical heat flux was proposed. It shows a good agreement with experimental data within the error band of 30%. Additionally, a unique approach to liquid film dryout modeling in annular flow was presented. It led to the development of the three-equation model based on consideration of liquid mass balance in the film, a two-phase mixture in the core and gas. The results of experimental validation of the model exhibit improvement in comparison to other models from literature.

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.

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