A Simplified Calibration of Liquid Hold-Up and Film Thickness in Annular Flow in Horizontal Pipe

AbstractAn X-ray microtomography (µCT) system was adapted so that 3D scans of fixed horizontal or vertical test sections can be performed. The mobile µCT system has been applied to measure the local, time-averaged volume fraction distribution of developing annular air-water flow in a horizontal pipe with µm spatial resolution. Based on the volume fraction data the liquid film thickness profile is computed and the accumulation, stripping and renewal of the annular liquid film at a circular orifice is studied. The development length of the annular flow downstream of the orifice is evaluated based on the integral volume fraction and the change of the film thickness profile along the pipe axis. Both parameters give a consistent result, indicating that liquid film renewal can be judged based on integral measurement techniques in this case. Further, the detailed 3D data enables the validation of computational fluid dynamics codes based on phase-averaged variables such as the Euler-Euler approach. Graphic abstract

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Experimental Investigation of Annular Flow Behaviour in Horizontal Pipe

International Journal of Integrated Engineering ◽

10.30880/ijie.2021.13.06.014 ◽

2021 ◽

Vol 13 (6) ◽

Author(s):

Osokogwu Osokogwu ◽

◽

Uche Uche ◽

Keyword(s):

Film Thickness ◽

Liquid Film ◽

Slug Flow ◽

High Speed ◽

Annular Flow ◽

Flow Behavior ◽

Liquid Film Thickness ◽

Experimental Investigations ◽

Internal Diameter ◽

Horizontal Pipe

The experimental investigations of annular flow were conducted in horizontal pipe using water/air in a 0.0504m internal diameter pipe loop with a total length of 28.68m. To understand annular flow behaviors, conductivity ring sensors, conductance probe sensors and Olympia high speed digital camera were used. In all the experiments, emphasis were on annular flow behavior, phase distribution and liquid film thickness. Liquid film thickness was observed to be thicker mostly when the superficial gas velocities were within 8.2699 m/s to 12.0675 m/s. Above the aforementioned superficial gas velocities, the flow became uniformly distributed on the walls of the internal pipe diameter hence reducing the thicker liquid film at the bottom with gas core at the center of the pipe. More so, annular-slug flow was discovered in the investigation. At superficial liquid velocity of 0.0505 m/s-0.1355 m/s on superficial gas velocities of 8.2699 m/s – 12.0675 m/s, annular-slug flow was prominent. Also discovered was at superficial liquid velocities of 0.0903 m/s - 0.1355 m/s with respect to superficial gas velocities of 13.1692 m/s – 23.4575 m/s, the pipe walls are fully covered with liquid film at very high speed at the entire walls (upper walls and bottom). Also discovered in this experiment is the wavy flow of the upper walls. The liquid film thickness that flows at the upper pipe walls, creeps in a wavy flow. Therefore, the entire flow behavior in an annular flow could be grouped into; wavy-flow at the upper walls, annular-slug flow and thicker liquid film at the bottom with gas core at the center.

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MODELLING AIR AND WATER TWO-PHASE ANNULAR FLOW IN A SMALL HORIZONTAL PIPE

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194516601587 ◽

2016 ◽

Vol 42 ◽

pp. 1660158 ◽

Cited By ~ 1

Author(s):

JUN YAO ◽

YUFENG YAO ◽

ANTONINO ARINI ◽

STUART MCIIWAIN ◽

TIMOTHY GORDON

Keyword(s):

Experimental Data ◽

Film Thickness ◽

Liquid Film ◽

Annular Flow ◽

Cfd Simulation ◽

Two Phase Flow ◽

Liquid Film Thickness ◽

Phase Flow ◽

Two Phase ◽

Horizontal Pipe

Numerical simulation using computational fluid dynamics (CFD) has been carried out to study air and water two-phase flow in a small horizontal pipe of an inner diameter of 8.8mm, in order to investigate unsteady flow pattern transition behaviours and underlying physical mechanisms. The surface liquid film thickness distributions, determined by either wavy or full annular flow regime, are shown in reasonable good agreement with available experimental data. It was demonstrated that CFD simulation was able to predict wavy flow structures accurately using two-phase flow sub-models embedded in ANSYS-Fluent solver of Eulerian–Eulerian framework, together with a user defined function subroutine ANWAVER-UDF. The flow transient behaviours from bubbly to annular flow patterns and the liquid film distributions revealed the presence of gas/liquid interferences between air and water film interface. An increase of upper wall liquid film thickness along the pipe was observed for both wavy annular and full annular scenarios. It was found that the liquid wavy front can be further broken down to form the water moisture with liquid droplets penetrating upwards. There are discrepancies between CFD predictions and experimental data on the liquid film thickness determined at the bottom and the upper wall surfaces, and the obtained modelling information can be used to assist further 3D user defined function subroutine development, especially when CFD simulation becomes much more expense to model full 3D two-phase flow transient performance from a wavy annular to a fully developed annular type.

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FILM THICKNESS IN ANNULAR FLOW

A-to-Z Guide to Thermodynamics Heat and Mass Transfer and Fluids Engineering ◽

10.1615/atoz.f.filthiinannflo ◽

2006 ◽

Vol f ◽

Keyword(s):

Film Thickness ◽

Annular Flow

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Simulation of the hydrodynamics in the onset of fouling for oil-water core-annular flow in a horizontal pipe

Journal of Petroleum Science and Engineering ◽

10.1016/j.petrol.2021.109084 ◽

2021 ◽

pp. 109084

Author(s):

Fan Jiang ◽

Haoyu Li ◽

Mathieu Pourquié ◽

Gijs Ooms ◽

Ruud Henkes

Keyword(s):

Annular Flow ◽

Horizontal Pipe ◽

Oil Water

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Measurement of Liquid Film Thickness in Micro Tube Annular Flow

2010 14th International Heat Transfer Conference, Volume 6 ◽

10.1115/ihtc14-23176 ◽

2010 ◽

Cited By ~ 1

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.

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