Showing papers on "Slug flow published in 2022"
TL;DR: In this article, the effects of four 90-degree horizontal elbows with different curvature radii (17, 34, 51, and 68 cm) and an identical rectangular cross-section (20 * 34mm) on a gas-liquid slug flow pattern have been studied experimentally and numerically.
Abstract: In the present research, the effects of four 90-degree horizontal elbows with different curvature radii (17, 34, 51, and 68 cm) and an identical rectangular cross-section (20 * 34 mm) on a gas–liquid slug flow pattern have been studied experimentally and numerically. Gas and liquid superficial velocities in numerical and experimental parts were set in 2.5 m/s and 0.44 m/s, respectively. In the computational fluid dynamics section, the distribution of volume fraction, velocity, pressure, turbulence intensity, and swirling intensity parameters were investigated using the VoF model and the SST k-ω method. Experimental studies were conducted utilizing pressure data and signal processing tools to study the dominant frequency of slug flow alongside bandwidth distribution as well as the Shannon entropy. The results exhibited that although the dominant frequency of slug flow did not change after passing the 90-degree elbow, the frequency signal's bandwidth increased. In this regard, the application of Shannon entropy quantity revealed that the frequency distribution signal experienced a greater increase in bandwidth as the elbows’ curvature radius increases. The turbulent intensity of the elbows’ outlet reveals that by increasing the curvature radius, the flow field behaves smoother. Also, swirling intensity distribution shows that decreasing the elbow radius leads to increment in the swirling intensity.
32 citations
TL;DR: In this article , the slug-flow induced vibration (SIV) of a catenary flexible riser with an aspect ratio of 360 is experimentally investigated in a small-scale air-water test loop, and the temporal-spatial mode competition is discussed in terms of the response amplitudes, frequencies, modal weights, transferred energy between the riser and flow, pressure fluctuations and slug flow characteristics.
15 citations
TL;DR: Wang et al. as mentioned in this paper adopted a new flow pattern classification method based on convolutional neural network (CNN) algorithms to achieve an automatic and objective identification of two-phase flow patterns.
15 citations
TL;DR: In this article, an experimental investigation on liquid-carrying by a swirling flow in an undulating pipeline was carried out, and the effect of swirl on flow patterns in the U-shaped tube was observed using a high-speed camera and processed with image processing technology.
12 citations
TL;DR: In this article , an experimental investigation on liquid-carrying by a swirling flow in an undulating pipeline was carried out, where a U-shaped tube with a diameter of 0.025 m was used to simulate a low-lying part.
10 citations
TL;DR: In this paper , the authors investigated the effects of hydrophilic-to-superhydrophobic discontinuous wall contact angles on gas-liquid slug flow in a T-junction microchannel.
10 citations
TL;DR: In this paper, the effect of interface deformation on flow patterns, recirculation flow, vorticity magnitude, and liquid film thickness of liquid-liquid two-phase flow in a confined microchannel was investigated via a simulation method using the VOF-CSF model.
9 citations
TL;DR: In this paper , a high speed camera was used to investigate the distribution of liquid-liquid two-phase flow and droplet dynamics in asymmetric parallel microchannels, and the factors affecting the stability and uniformity of droplets were explored.
9 citations
TL;DR: In this article, the authors studied the flow patterns of six liquid-liquid systems in a numbered-up microfluidic set-up and determined flow non-uniformity based on both the volumetric flow rate and slug size/droplet size/interface position for each microchannel.
9 citations
TL;DR: In this paper , the authors studied the flow patterns of six liquid-liquid systems in a numbered-up microfluidic set-up and determined flow non-uniformity based on both the volumetric flow rate and slug size/droplet size/interface position for each microchannel.
8 citations
TL;DR: In this article , the authors investigated flow-induced vibrations for air-water two-phase passing through bends and found that the excitation forces of a twophase flow in a piping structure are highly dependent on the flow pattern and the two phase flow conditions upstream of the U-bend.
TL;DR: In this paper , the influence of gas-liquid phase velocity on the flow pattern was investigated, and numerical simulation has been carried out by using the Reynolds stress model and the level set model.
Abstract: The gas–liquid contact area can be increased by the gas–liquid swirl flow, and the heat and mass transfer efficiency between gas and liquid can be enhanced by the gas–liquid swirl flow. The gas hydrate formation can be promoted by the swirl flow. The swirl flow can ensure the safety of the natural gas hydrate slurry. The flow pattern and conversion law of gas–liquid swirl with a twist tape should be investigated, and numerical simulation has been carried out by using the Reynolds stress model and the level set model. As a result, four different flow patterns are obtained, namely, swirl-stratified flow, swirl bubble flow, swirl slug flow, and swirl annular flow. The influence of gas–liquid-phase velocity on the flow pattern is investigated. The drag force generated by the two-phase slip velocity can change the gas form. At the same time, the flow pattern at different positions of the pipe will also change because of the attenuation of the swirl flow. Finally, the flow pattern map of the gas–liquid swirl flow is accomplished, and it is compared with the Mandhane flow pattern map. The flow boundary of the swirl bubble flow and the swirl annular flow is predicted.
TL;DR: In this paper , a hybrid thermal multiphase model consisting of the pseudopotential multi-phase lattice Boltzmann model and the finite difference method is employed to investigate the flow boiling heat transfer in a serpentine microchannel.
TL;DR: In this paper , a mechanistic model of flow and heat transfer for upward two-phase slug flow in vertical pipes is developed based on the hypothesis of the slug unit cell and the overall heat transfer coefficient is integrated by using the local heat transfer coefficients of liquid slug and the Taylor bubble region.
Abstract: Two-phase slug flow exhibits intrinsically stochastic and statistically periodic flow behaviors. Understanding the mechanisms of flow and heat transfer of upward two-phase slug flow is important. This paper develops a mechanistic model of flow and heat transfer for upward two-phase slug flow in vertical pipes. First, a hydrodynamic model of two-phase slug flow in regular-sized channels is developed based on the hypothesis of the slug unit cell. Each slug unit cell is hypothesized to be composed of a liquid slug and a Taylor bubble region. Second, a mechanistic heat transfer model is derived based on the hydrodynamic model. The overall heat transfer coefficient is integrated by using the local heat transfer coefficients of liquid slug and the Taylor bubble region. Third, the proposed mechanistic model is validated by the experimental void fraction, pressure drop, and two-phase heat transfer coefficient from different sources. Finally, the effect of flow geometry and parameters—such as superficial gas and liquid velocities, void fraction, slug frequency, pressure drop, and the ratio of slug length to unit cell length—on heat transfer in two-phase slug flow is comprehensively investigated. The enhancement in heat transfer in two-phase slug flow compared with that of single-phase flow can be attributed to an increase in the turbulence of the liquid due to the injection of air and a reduction in the thermal boundary layer owing to the frequent alternation between liquid slug and the Taylor bubble.
TL;DR: In this paper , the authors investigated the effect of capillary wall wettability on the hydrodynamics of liquid-liquid two-phase flow in a capillary tube with an inner diameter of 2.4 mm and a length of 40 cm.
TL;DR: In this paper , the effect of interface deformation on flow patterns, recirculation flow, vorticity magnitude, and liquid film thickness of liquid-liquid two-phase flow in a confined microchannel was investigated via a simulation method using the VOF-CSF model.
TL;DR: In this article , an investigation of thermal performances of the flat plate pulsating heat pipe and liquid-vapor interfaces oscillation influence on the flow pattern inside FPPHP for microgravity conditions have been performed.
TL;DR: In this article, a test facility to investigate flow pattern transitions of vertical two-phase flow of CO2 has been built within the scope of the high-luminosity detector upgrades at the European Organization for Nuclear Research (CERN).
TL;DR: In this paper, the authors discuss the phenomenology of bubble breakup and coalescence in a vertical pipe mounted with an expansion followed by a contraction, and show that burst events are majorly ruled by the dynamic pressure forces of the turbulent motion.
TL;DR: In this paper , Zhang et al. demonstrated the artificial neural network (ANN) ability for predicting slug liquid holdup (HLS), using 2525 measured points from 20 experimental studies.
TL;DR: In this paper , a novel two-phase flow enhanced direct contact membrane distillation (TP-DCMD) system was developed and well validated using the mass and energy conservations.
TL;DR: In this paper , a test facility to investigate flow pattern transitions of vertical two-phase flow of CO 2 has been built within the scope of the high-luminosity detector upgrades at the European Organization for Nuclear Research (CERN).
TL;DR: In this paper, a new method is proposed by combining electrostatic sensing and digital imaging techniques to obtain moisture contents, drying models, moisture diffusivities, activation energies and mass transfer coefficients of biomass at different bubble locations.
TL;DR: In this article, an investigation of thermal performances of the flat plate pulsating heat pipe and liquid-vapor interfaces oscillation influence on the flow pattern inside FPPHP for microgravity conditions have been performed.
TL;DR: In this article, the authors developed an interfacial drag model for rectangle channel bubbly and slug flow to predict the phase distribution of air-water flow in rectangular channels, including void fraction, interfacial area concentration, and bubble chord length.
TL;DR: In this paper , high-speed video imaging techniques were used to capture two-phase flow behavior corresponding to different superficial gas and liquid velocities, and the results showed that the mixer configuration can affect the flow structure only in the slug flow regime.
DOI•
01 Mar 2022TL;DR: In this article, a review of the top-side measurements-based slug control techniques is presented, along with necessary recommendations for enhanced control performance provided to prevent slug flow in offshore oil production.
Abstract: Slugging flow is a condition caused by a liquid obstruction at the riser base. It exhibits cyclic behaviour. The cycle consists of a protracted time of no gas production at the riser's top, followed by the arrival of a liquid slug with a length greater than the riser height, and ultimately the breakthrough of a significant gas surge. The cycle time might range from a few minutes to a few hours, depending on the system size and flow conditions. In offshore oil production, feedback control is a practical and cost-effective way to prevent slug flow. To control the flow rate or the pressure in the pipeline, adjusting the choke valve opening on the topside facility is generally utilised as the control input. From a practical standpoint, designing a control system based on topside data rather than seabed measurements is preferable. Controlling the topside pressure alone is difficult and ineffective in reality, but combining it with the flow rate results in a more reliable control solution. Measuring the flow rate of a multiphase flow, on the other hand, is difficult and expensive. All the topside measurements-based slug control techniques was critically reviewed and necessary recommendations for enhanced control performance provided. In conclusion, this review acknowledged that slugging is a well-defined flow pattern, yet despite having been studied for several decades, current slug control methods still have robustness issues. Slug flow problems are expected to become even more intense in the future as a result of longer vertical risers driven by deep-water Exploration and Production (E&P).
TL;DR: In this article, a deep learning technique has been used to classify the flow patterns and extract their attributes in a particular capillary using multi-spectral segmentation, where the modified Weber, Froude, and Bond numbers are used by considering the absolute velocities, accelerations, and bubble lengths for classifying the flow regime.
TL;DR: In this paper , the authors developed an interfacial drag model for rectangle channel bubbly and slug flow to predict the phase distribution and interfacial area concentration in bubble, Taylor bubble, and liquid slug.
TL;DR: In this paper , the authors examined the influence of the discontinuous wettability of a microchannel's wall on bubble structure movement under microgravity conditions, and found that wall-adhesion equations can predict the form of the bubble/liquid interface at and near the wall.