PRESSURE FLUCTUATIONS OF LIQUID-LIQUID SLUG FLOW IN CROSS-JUNCTION SQUARE MICROCHANNELS

In this paper the Navier-stokes equations for a single liquid slug have been solved in order to predict the circulation patterns within the slug. Surface tension effects on the air-water interface have been investigated by solving the Young–Laplace equation. The calculated interface shape has been utilized to define the liquid slug geometry at the front and tail interfaces of the slug. Then the effects of the surface tension on the hydrodynamics of the two-phase slug flow have been compared to those where no surface tension forces exist. The importance of the complex flow field features in the vicinity of the two interfaces has been investigated by defining a non-dimensional form of the wall shear stress. The latter quantity has been formulated based on non-dimensional parameters in order to define a general Moody friction factor for typical two-phase slug flows in microchannels. Moreover, the hydrodynamics of slug flow formation has been examined using computational fluid dynamics (CFD). The volume-of-fluid (VOF) method has been applied to monitor the growth of the instability at the air-water interface. The lengths of the slugs have been correlated to the pressure fluctuations in the mixing region of the air and water streams at an axisymmetric T-junction. The main frequencies of the pressure fluctuations have been investigated using the Fast Fourier Transform (FFT) method.

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Two-Phase Flow Induced Force Fluctuations on Pipe Bend

Volume 2B: Thermal Hydraulics ◽

10.1115/icone22-30573 ◽

2014 ◽

Cited By ~ 2

Author(s):

Shuichiro Miwa ◽

Yang Liu ◽

Takashi Hibiki ◽

Mamoru Ishii ◽

Yoshiyuki Kondo ◽

...

Keyword(s):

Flow Regime ◽

Slug Flow ◽

Two Phase Flow ◽

Pressure Fluctuations ◽

Flow Regimes ◽

Phase Flow ◽

Liquid Slug ◽

Two Phase ◽

Pipe Bend ◽

Force Fluctuation

In this study, fluctuating force induced by both upward and horizontal gas-liquid two-phase flow on 90 degree pipe bend at atmospheric condition was investigated. First, the database comprised of dynamic force signals and two-phase flow parameters such as volumetric fluxes, area averaged void fraction and pressure fluctuations covering entire two-phase flow regimes was developed for both flow orientations. Then, study was conducted to develop a model which is capable of predicting the force fluctuation frequency and magnitudes particularly for the slug flow regime. The model was fundamentally developed from the local instantaneous two-fluid model which was applied to the control volume around the elbow test section. Main contribution of the force fluctuation of two-phase flow is from the momentum and pressure fluctuations for most of the flow regimes. For slug flow regime, however, water-hammer like impact was produced by the collision of liquid slug against the structure surface. In order to consider that effect, the liquid slug impact force model was developed. The model utilizes two-group interfacial area concentration correlation to treat the flow regime transition without an abrupt discontinuity. It was found that the newly developed model is capable of predicting two-phase flow induced force fluctuation and dominant frequency range with satisfactory accuracy for flow regimes up to churn-turbulent.

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Simulation Study on the Development Process and Phase Interface Structure of Gas-Liquid Slug Flow in a Horizontal Pipe

Frontiers in Energy Research ◽

10.3389/fenrg.2021.762471 ◽

2021 ◽

Vol 9 ◽

Author(s):

Xiao Wu ◽

Zhaoting Wang ◽

Mei Dong ◽

Quan Ge ◽

Longfei Dong

Keyword(s):

Velocity Field ◽

Slug Flow ◽

Development Process ◽

Pressure Fluctuations ◽

Phase Interface ◽

Interface Structure ◽

Liquid Slug ◽

Two Phase ◽

Horizontal Pipe ◽

Open Source Software Package

Here, a unified 3D numerical model of gas-liquid two-phase flow in a horizontal pipe was established using the interface capture method based on the open source software package OpenFOAM. Through numerical simulation of the natural slugging and development process of slug flow under different working conditions, the motion, phase interface structure, pressure and velocity field distributions of the liquid slug were fully developed and analyzed. The simulation results are consistent with the experiment. The results showed that during the movement of the slug head, there is a throwing phenomenon and a wave-like motion of the liquid slug. In addition, the slug tail and body area have very similar velocity profiles, and the overall velocity field distribution becomes more uniform with the development of liquid slug. Moreover, there are sudden pressure fluctuations at the head and tail of the liquid slug.

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