Gas-liquid Two-phase Flow Research Articles

Enhancing Gas-Liquid Two-Phase Stratified Flow Imaging with EIGEN-NET: A Fusion of Deep Learning and Measurement Matrices

Abstract Gas-liquid two-phase stratified flow is a common occurrence in various industries, demanding real-time monitoring and precise measurement for safety and operational efficiency. Current methods primarily rely on sensors or limited imaging technologies, leaving room for improvement. In this paper, we introduce the EIGEN-Net framework, specifically designed for real-time monitoring of gas-liquid
stratified flow within pipelines, utilizing Electrical Impedance Tomography(EIT). EIT, a noninvasive imaging method, shows potential despite challenges from gas affecting voltage stability in image reconstruction. EIGEN-Net capitalizes on measurement matrices and deep learning to enhance measurement accuracy. It extracts crucial physical properties characterizing liquid fractions and employs acquired voltage data to pre-reconstruct a tensor. By fusing these tensors with prior information, it significantly improves imaging outcomes, effectively addressing data insufficiency issues. The incorporation of adaptive information into deep learning networks eliminates the necessity for data classification. Moreover, this approach accommodates scenarios of continuous flow variation, enhancing imaging resolution. EIGEN-Net’s versatility extends to other two-phase flow scenarios and sensor measurement matrices, holding promise for applications in various industrial inspection domains. 
EIGEN-Net: Deep Learning Fusion Network Guided by Leading Eigenvalues of Measurement Matrix

An Application of Upwind Difference Scheme with Preconditioned Numerical Fluxes to Gas-Liquid Two-Phase Flows

A time-consistent upwind difference scheme with a preconditioned numerical flux for unsteady gas-liquid multiphase flows is presented and applied to the analysis of cavitating flows. The fundamental equations were formulated in general curvilinear coordinates to apply to diverse flow fields. The preconditioning technique was applied specifically to the numerical dissipation terms in the upwinding process without changing the time derivative terms to maintain time consistency. This approach enhances numerical stability in unsteady multiphase flow computations, consistently delivering time-accurate solutions compared to conventional preconditioning methods. A homogeneous gas-liquid two-phase flow model, third-order Runge-Kutta method, and the flux difference splitting upwind scheme coupled with a third-order MUSCL TVD scheme were employed. Numerical tests of two-dimensional gas-liquid single- and two-phase flows over backward-facing step with different step height and flow conditions successfully demonstrated the capability of the present scheme. The calculations remained stable even for flows with a very low Mach number of 0.001, typically considered incompressible flows, and the results were in good agreement with the experimental data. In addition, we analyzed unsteady cavitating flows at high Reynolds numbers and confirmed the effectiveness and applicability of the present scheme for calculating unsteady gas-liquid two-phase flows.

Effect of the operation pressure on severe slugging in a gas-liquid two-phase flow in the pipeline-riser system

Effect of the operation pressure on severe slugging in a gas-liquid two-phase flow in the pipeline-riser system

Bubble-shape-based velocity measurement of horizontal gas–liquid two-phase flows using wire-mesh sensor

Bubble-shape-based velocity measurement of horizontal gas–liquid two-phase flows using wire-mesh sensor

Effect of solid particles on the hydrodynamics of vertical upward gas–liquid two-phase flow: Pressure drop analysis

Effect of solid particles on the hydrodynamics of vertical upward gas–liquid two-phase flow: Pressure drop analysis

Vertical two-phase flow regimes in an annulus image dataset - Texas A&M university.

The Vertical Two-Phase Flow Regimes in an annulus Image Dataset, generated at Texas A&M University, presents an extensive collection of high-resolution images capturing various gas-liquid two-phase flow dynamics within a vertical flow setup. This dataset results from meticulous experimental work in the 140 ft Tower Lab, utilizing a combination of water and air flows to simulate real-world conditions and employing high-quality video recordings to document flow regime transitions. Designed to support research in fluid dynamics, machine vision, and computational modeling, the dataset offers valuable resources for developing machine vision models for accurate regime detection and differentiation, enhancing the fidelity of computational fluid dynamics simulations, and facilitating the estimation of critical flow parameters. Despite its comprehensive nature, the dataset notes limitations such as the absence of annular flow regime images and its exclusive focus on vertical flow conditions.

Numerical Simulation on Hybrid Lifting Operation of Polymetallic Nodules and Rare-Earth Elements-Rich Mud by Air-Lift Pump in Deep Sea Around Minamitorishima Island

Polymetallic nodules and REE-rich mud under the seabed of 5500–5700 m water depth around Minamitorishima island are promising and attractive for exploration and development. Following our previous research, numerical analysis was used to investigate the unsteady flow characteristics and the lifting performance of a commercial production system using an air-lift pump for hybrid lifting, lifting both polymetallic nodules and REE-rich mud. Gas–liquid–solid three-phase flow and gas–liquid two-phase flow in the system were analyzed using the one-dimensional drift–flux model. First, the reliability of the schemes and program was verified by comparing the numerical results with the experimental ones. Next, numerical simulations were conducted, in which the model’s dimensions were related to a commercial production system operated in the deep sea around Minamitorishima island, and the conditions fit the expected production rate. The results revealed the unsteady flow characteristics under the operations, such as start-up, shut-down, feed of polymetallic nodules and REE-rich mud, and those associated with disturbances, such as feed rate fluctuations. We demonstrate that the program and the schemes can simulate the unsteady flow characteristics and the lifting performance of a commercial production system with an air-lift pump well, and they can derive useful information and know-how in advance for the safe and continuous operation of the system.

Study of Gas–Liquid Two-Phase Flow Characteristics at the Pore Scale Based on the VOF Model

To study the effects of liquid properties and interface parameters on gas–liquid two-phase flow in porous media. The volume flow model of gas–liquid two-phase flow in porous media was established, and the interface of the two-phase flow was reconstructed by tracing the phase fraction. The microscopic imbibition flow model was established, and the accuracy of the model was verified by comparing the simulation results with the classical capillary imbibition model. The flow characteristics in the fracturing process and backflow process were analyzed. The influence of flow parameters and interface parameters on gas flow was studied using the single-factor variable method. The results show that more than 90% of the flowing channels are invaded by fracturing fluid, and only about 50% of the fluid is displaced in the flowback process. Changes in flow velocity and wetting angle significantly affect Newtonian flow behavior, while variations in surface tension have a pronounced effect on non-Newtonian fluid flow. The relative position of gas breakthrough in porous media is an inherent property of porous media, which does not change with fluid properties and flow parameters.

A Neural Network approach to optimize flow rate for Micro-Bubble Drag Reduction

To reduce the resistance of ships, many scholars have focused on micro-bubble drag reduction (MBDR) technology. However, The implementation of MBDR on ships is challenging due to the numerous factors and complex coupling relationships involved in the gas–liquid two-phase flow at the ship’s bottom. This paper aims to apply neural network algorithm on MBDR technology to real ships to achieve energy savings and emission reductions. A test platform was constructed, and the Micro-Bubble Flow Rate of the test model at the lowest drag resistance was collected to form a sample database. Using the database as a sample, the mathematical model is trained by the neural network algorithm, and optimized by the genetic algorithm through a number of iterations, the Optimal Micro-Bubbles Flow Rate (OMFR) is predicted for each status. This paper is of great significance to the application of MBDR technology on real ships. Using neural network algorithm to form the mathematics model from the data samples of unconstrained self-propulsion tests. The OMFR obtained through the iterative process of the genetic algorithm, can reduce the ship resistance, thereby achieving energy savings and emission reductions.

Characterization of the horizontal gas–liquid two-phase flow patterns using acoustic measurement techniques

Characterization of the horizontal gas–liquid two-phase flow patterns using acoustic measurement techniques

Slug void fraction in vertical downward gas–liquid two-phase flow

Slug void fraction in vertical downward gas–liquid two-phase flow

Hidden Markov Model Combined With Gated Recurrent Unit for Global Status Monitoring of Gas–Liquid Two-Phase Flow

Hidden Markov Model Combined With Gated Recurrent Unit for Global Status Monitoring of Gas–Liquid Two-Phase Flow

An EMAT Guided Wave Tomography System for Gas-liquid Two-phase Flow Imaging

An EMAT Guided Wave Tomography System for Gas-liquid Two-phase Flow Imaging

Effects of water ingestion on the aerodynamic performance of an axial compressor

Liquid water in the atmosphere affects the safety and stability of aero-engines in their operation and threatens flight safety because when liquid water is ingested by compressors, it breaks into smaller droplets, which then bounce in, collide with, or splash onto the blades of compressors, increasing profile loss and aerodynamic drag. As a result, the performance of compressors would deteriorate after water ingestion. To investigate the mechanisms underlying such performance changes and flow differences within the passage due to water ingestion, we simulate the gas-liquid two-phase flow within National Aeronautics and Space Administration Rotor 67 by employing the Eulerian–Lagrangian approach. This paper investigates water–air ratios ranging from 3% to 9% of the total mass and droplet diameters between 500and 1500 μm. Numerical simulations are used to examine the flow and performance of the compressor under different inlet conditions. The results demonstrate that higher water ingestion rates and smaller droplet diameters decrease the compressor efficiency, due to increased entropy generation. They also reduce the mass flow rate, due to droplet accumulation blocking the passage. Specifically, water droplets reduce the axial velocity and significantly increase boundary layer separation losses on the blade suction surface. In addition, water ingestion partially mitigates tip clearance leakage flow losses, slightly weakens the shock intensity, and shifts the shock position forward, while delivering minimal impact on wake losses.

Experimental Investigation of Gas-Liquid Two-Phase Flow Separation Behaviors in a U-Type Separator

Experimental Investigation of Gas-Liquid Two-Phase Flow Separation Behaviors in a U-Type Separator

Adaptive mesh refinement for VOF modeling gas-liquid two-phase flow: A summary of some algorithms and applications

Adaptive mesh refinement for VOF modeling gas-liquid two-phase flow: A summary of some algorithms and applications

Void fraction measurement of gas-liquid two-phase flow based on a multi-frequency CCEIT system

Void fraction measurement of gas-liquid two-phase flow based on a multi-frequency CCEIT system

Flow pattern recognition for horizontal gas-liquid two-phase flow with a hybrid deep-learning model

Flow pattern recognition for horizontal gas-liquid two-phase flow with a hybrid deep-learning model

Characterization of Purged Gas-Liquid Two-Phase Flow in a Molten Salt Regulating Valve

Characterization of Purged Gas-Liquid Two-Phase Flow in a Molten Salt Regulating Valve

A numerical study of two identical CO2 bubbles rising side by side in water coupled with mass transfer

ABSTRACT In contrast to the relatively straightforward rising dynamics of single bubbles, the behavior of multiple bubbles involves a more intricate interplay of flow field dynamics, trajectory patterns, morphological changes, and mass transfer phenomena. To reveal the coalescence characteristics and mass transfer effects of CO2 bubbles during the rising process, this study developed a coupled mass transfer numerical model for bubbles. The Volume of Fluid (VOF) method was used in combination with a mass transfer code for solving the model. The effects of bubble pair initial spacing and liquid viscosity on the coalescence and mass transfer were discussed. The numerical simulation results show that as the initial distance between the two bubbles decreases, the interaction force between the bubbles increases, and the possibility of bubble coalescence increases, the coalescence behavior reduces the contact area and thus decreases the amount of CO2 dissolved about 24.07%. When the initial viscosity of the liquid phase is low, there is an oscillation in the bubble velocity, and the two bubbles tend to merge. As the initial viscosity of the liquid phase increases, resistance increases, causing a decrease in bubble velocity. Consequently, the path of bubble ascent shifts from “approach-repulsion-approach” to “continuous repulsion.” The viscous resistance reduces the gas–liquid contact area, resulting in a corresponding decrease in the mass transfer rate, the dissolution amount of carbon dioxide decreased by approximately 24.42% in this case. The exploration of coupled fluid dynamics and mass transfer phenomena at the multi-bubble scale holds paramount importance in guiding the design and exploration of gas–liquid two-phase flow systems.