Numerical Simulation of Bubble Formation in Co-Flowing Mercury

2008 ◽  
Author(s):  
Ashraf Ibrahim ◽  
Mark Wendel ◽  
David Felde ◽  
Bernard Riemer
Keyword(s):  
Acoustic Waves ◽  
Bubble Growth ◽  
Gas Flow ◽  
Bubble Formation ◽  
Science Center ◽  
Proton Radiography ◽  
Two Phase ◽  
Vof Model ◽  
Computational Fluid Dynamics Cfd ◽  
Bubble Sizes

In this work, we present computational fluid dynamics (CFD) simulations of helium bubble formation and detachment at a submerged needle in stagnant and co-flowing mercury. Since mercury is opaque, visualization of internal gas bubbles was done with proton radiography (pRad) at the Los Alamos Neutron Science Center (LANSCE2). The acoustic waves emitted at the time of detachment and during subsequent oscillations of the bubble were recorded with a microphone. The Volume of Fluid (VOF) model was used to simulate the unsteady two-phase flow of gas injection in mercury. The VOF model is validated by comparing detailed bubble sizes and shapes at various stages of the bubble growth and detachment, with the experimental measurements at 1.66 mg/min helium gas flow rate and different mercury velocities. The experimental and computational results show a two-stage bubble formation in stagnant mercury. The first stage involves growing bubble around the needle, and the second follows as the buoyancy overcomes wall adhesion. The comparison of predicted and measured bubble sizes and shapes at various stages of the bubble growth and detachment is in good agreement.

Gas Bubble Formation in Stagnant and Flowing Mercury

2007 ◽  
Author(s):  
Mark Wendel ◽  
Ashraf Ibrahim ◽  
David Felde ◽  
Bernard Riemer
Keyword(s):  
Acoustic Waves ◽  
Gas Flow ◽  
Power Level ◽  
High Surface ◽  
Beam Power ◽  
Outer Diameter ◽  
Science Center ◽  
Proton Radiography ◽  
Oak Ridge ◽  
Bubble Sizes

The Oak Ridge National Laboratory’s (ORNL) Spallation Neutron Source (SNS) facility uses a liquid mercury target that flows through a stainless steel containment vessel. As the SNS pulsed beam power level is increased, it is expected that the target vessel lifetime could become limited by cavitation damage erosion (CDE). Bubbles produced in mercury at an upwards-oriented vertical gas injector needle were observed with proton radiography (pRad) at the Los Alamos Neutron Science Center (LANSCE). The comparison of volume-of-fluid (VOF) simulation results to the radiographic images reveals some aspects of success and some deficiencies in predicting these high surface tension, highly buoyant, and non-wetting fluid behavior. Although several gas flows were measured with pRad, this paper focuses on the case with a low gas flow rate of 1.66 mg/min (10 sccm) through the 0.2-mm-outer-diameter injector needle. The acoustic waves emitted due to the detachment of the bubble and during subsequent bubble oscillations were also recorded with a microphone, providing a precise measurement of the bubble sizes. When the mercury is also motivated coaxially, the drag on the bubble forces earlier detachment leading to smaller bubble sizes.

Optimized Gun Barrel Based on Numerical Simulation to Produced Oil With Low BSW Content

2020 ◽  
Author(s):  
Silvia Araujo Daza ◽  
Urbano Montañez Villamizar
Keyword(s):  
Flow Rate ◽  
Operating Conditions ◽  
Water Mixture ◽  
Two Phase ◽  
Ansys Fluent ◽  
Inlet Flow ◽  
Gun Barrel ◽  
Vof Model ◽  
Inlet Flow Rate ◽  
Computational Fluid Dynamics Cfd

Abstract This work presents the methodology and results of the optimization of the internals (Inlet distributor, oil and water collectors) of a 20,000 BPD (0.037 m3/s) gun-barrel tank starting from an existing design. Computational fluid dynamics (CFD) was applied to simulate and evaluate the performance of various internal configurations. These simulations were performed to determine the best configuration to ensure efficient separation of the oil-water mixture and oil with a low BSW content < 2% at the outlet. The simulations were carried out using the commercial software ANSYS Fluent under the two-phase flow VOF model and k-ε realizable turbulence model. Further CFD simulations were performed to evaluate the behavior of the gun barrel tank under different operating conditions (Different inlet flow rate) and to determine the maximum operation flow which allows obtaining the crude-oil with a maximum BSW content of 0.5%. From the simulation results, an operating curve (operating flow vs retention time) was constructed. This information allows, in practice, to identify the inlet flow rate based on the desired content of BSW in the separated oil.

Direct Numerical Simulation of Bubble Formation Through a Submerged “Flute” with Experimental Validation

2021 ◽  
Author(s):  
Naveen Pillai ◽  
Nicholas Sponsel ◽  
Katharina Stapelmann ◽  
Igor A Bolotnov
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Single Phase ◽  
Bubble Formation ◽  
Computational Cost ◽  
Interface Tracking ◽  
Two Phase ◽  
Nozzle Hole ◽  
Computational Fluid Dynamics Cfd ◽  
Physical Phenomena

Abstract Direct Numerical Simulation (DNS) is often used to uncover and highlight physical phenomena that are not properly resolved using other Computational Fluid Dynamics (CFD) methods due to shortcuts taken in the latter to cheapen computational cost. In this work we use DNS along with interface tracking to take an in-depth look at bubble formation, departure, and ascent through water. To form the bubbles air is injected through a novel orifice geometry not unlike that of a flute submerged underwater, which introduces phenomena that are not typically brought to light in conventional orifice studies. For example, our single-phase simulations show a significant leaning effect wherein pressure accumulating at the trailing nozzle edges leads to asymmetric discharge through the nozzle hole, and an upward bias in the flow in the rest of the pipe. In our two-phase simulations, this effect is masked by the surface tension of the bubble sitting on the nozzle, but it can still be seen following departure events. After bubble departure, we observe the bubbles converge towards an ellipsoidal shape, which has been validated by experiments. As the bubbles rise, we note that local variations in the vertical velocity cause the bubble edges to flap slightly, oscillating between relatively low and high velocities at the edges. Thus, causing the bubble edges to periodically lag and lead the bulk bubble mass.

CFD STUDY OF CYCLONE PERFORMANCE: EFFECT OF INLET SECTION ANGLE AND PARTICLE SIZE DISTRIBUTION

2016 ◽  
Vol 78 (6-4) ◽  
Author(s):  
Ratchanon Piemjaiswang ◽  
Kongpob Ratanathammapan ◽  
Prapan Kunchonthara ◽  
Pornpote Piumsomboon ◽  
Benjapon Chalermsinsuwan
Keyword(s):  
Pressure Drop ◽  
Gas Flow ◽  
Collection Efficiency ◽  
Solid Particles ◽  
Inlet Section ◽  
Two Phase ◽  
Performance Effect ◽  
Computational Fluid Dynamics Cfd ◽  
Inlet Angle ◽  
Numerical Simulation Technique

A numerical simulation technique was employed to model the two phase flow in cyclones using computational fluid dynamics (CFD). Three different inlet angles of cyclone, including 45, 0 and -45 degrees were compared to describe the efficiency of the conventional cyclone with the modified inlet angle ones. The results showed that the interaction between solid particles in dilute system could be neglected. The pressure drop was decreased when the inlet angle of the cyclone increased. The cyclone with 45 degrees inlet angle tended to have the lowest pressure drop. The collection efficiency was improved with 45 degrees inlet angle due to high swirling motion of gas flow. 

Quantification of Mixing in RIM Using a Non-Diffusive Two-Phase Flow Numerical Model

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Cláudio P. Fonte ◽  
Ricardo J. Santos ◽  
Madalena M. Dias ◽  
José Carlos B. Lopes
Keyword(s):  
Fluid Dynamics ◽  
Reynolds Number ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Linear Scale ◽  
Cfd Simulations ◽  
Two Phase ◽  
Vof Model ◽  
Mixing Chamber ◽  
Computational Fluid Dynamics Cfd

Mixing in RIM is made mainly by advective mechanisms, rather than diffusion. In this paper, the advective mechanisms that enable reducing the mixing scales down to the values required for the complete chemical reaction of the two monomers inside the RIM mixing chamber are identified and studied. From Computational Fluid Dynamics (CFD) simulations of non-diffusive two-phase flow using the Volume-of-Fluid (VOF) model, a linear scale of segregation is determined as a measure of the degree of mixing and the effect of the Reynolds number is studied.

Influence of Jordanian zeolite on the performance of a solar still: experiments and CFD simulation studies

2016 ◽  
Vol 16 (6) ◽  
pp. 1700-1709 ◽  
Author(s):  
Yazan Taamneh
Keyword(s):  
Experimental Data ◽  
Phase Change ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Solar Still ◽  
Cfd Simulations ◽  
Two Phase ◽  
Vof Model ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

Computational fluid dynamics (CFD) simulations were performed for experiments carried out with two identical pyramid-shaped solar stills. One was filled with Jordanian zeolite-seawater and the second was filled with seawater only. This work is focused on CFD analysis validation with experimental data conducted using a model of phase change interaction (evaporation-condensation model) inside the solar still. A volume-of-fluid (VOF) model was used to simulate the inter phase change through evaporation-condensation between zeolite-water and water vapor inside the two solar stills. The effect of the volume fraction of the zeolite particles (0 ≤ ϕ ≤ 0.05) on the heat and distillate yield inside the solar still was investigated. Based on the CFD simulation results, the hourly quantity of freshwater showed a good agreement with the corresponding experimental data. The present study has established the utility of using the VOF two phase flow model to provide a reasonable solution to the complicated inter phase mass transfer in a solar still.

scholarly journals Conical Two-Phase Swirl Flow Atomizers—Numerical and Experimental Study

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1745
Author(s):  
Marek Ochowiak ◽  
Daniel Janecki ◽  
Andżelika Krupińska ◽  
Sylwia Włodarczak ◽  
Tomasz Wilk ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Gas Flow ◽  
Experimental Studies ◽  
Swirl Flow ◽  
Spray Angle ◽  
Operational Parameters ◽  
Two Phase ◽  
Additional Information ◽  
Swirl Chamber ◽  
Computational Fluid Dynamics Cfd

This paper presents the results of numerical simulations for the developed and discussed conical two-phase atomizers with swirl flow, differing in the ratio of the height of the swirl chamber to its diameter. Experiments were carried out for SAN-1 with HS/DS = 1 and SAN-2 with HS/DS = 4 atomizers. The study was conducted over a range of Reynolds number for liquid ReL = (1400; 5650) and for gas ReG = (2970; 9900). Numerical calculations were performed with the use of computational fluid dynamics (CFD), which were verified on the basis of experimental data. Based on the analysis of experimental studies and simulations results the influence of operational parameters and changes of the atomizer geometry on the generated spray was demonstrated. As the gas flow rate increased and the swirl chamber height decreased, the spray angle increased. Higher velocity values of the liquid and greater turbulence occur in the center of the spray. The flow inside the atomizer determines the nature of the spray obtained. The geometry of the swirl chamber influences the air core formed inside the atomizer, and this determines the atomization effect. The results of numerical simulations not only confirm the results of experimental studies, but also provide additional information on internal and external fluid flow.

Modeling and Experimental Investigation of Bubble Formation in Shear-Thinning Liquids

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Mohamad Taghi Esfidani ◽  
Mohammad Reza Oshaghi ◽  
Hossein Afshin ◽  
Bahar Firoozabadi
Keyword(s):  
Power Law ◽  
High Speed ◽  
Gas Flow ◽  
Bubble Formation ◽  
Experimental Studies ◽  
Methyl Cellulose ◽  
Operating Conditions ◽  
Wide Range ◽  
Bubble Sizes ◽  
Newtonian Liquids

This investigation presents both theoretical and experimental studies on the size of a growing bubble in power-law non-Newtonian liquids. At first, some previous works on the prediction of bubble size in Newtonian liquids have been extended by considering the balance of forces acting on the bubble at the moment of separation. Predicted bubble sizes were validated against the experimental results for a wide range of operating conditions, including different gas flow rates and needle diameters as well as a wide range of physical properties of the Newtonian liquids. Furthermore, in order to determine the size of the bubbles formed in power-law non-Newtonian liquids with a similar analysis, the effective shear rate of bubble growth was calculated in which the rheological properties of fluid were taken into account and subsequently the viscosity of the fluid was modified. Theoretically obtained bubble sizes for non-Newtonian liquids are in a good agreement with our experimental high-speed video observations of three carboxyl methyl cellulose (CMC) solutions.

scholarly journals Gas-liquid slug formation at a rectangular microchannel T-junction: A CFD benchmark case

2011 ◽  
Vol 1 (4) ◽  
Author(s):  
Rafael Santos ◽  
Masahiro Kawaji
Keyword(s):  
Experimental System ◽  
Velocity Slip ◽  
Liquid Slug ◽  
Two Phase ◽  
Experimental Conditions ◽  
Rectangular Microchannel ◽  
Flow Rates ◽  
Frictional Pressure Drop ◽  
Vof Model ◽  
Computational Fluid Dynamics Cfd

AbstractComputational fluid dynamics (CFD) is an important tool for development of microfluidic systems based on gasliquid two-phase flow. The formation of Taylor slugs at microchannel T-junctions has been studied both experimentally and numerically, however discrepancies still exist because of difficulties in correctly representing experimental conditions and uncertainties in the physics controlling slug flow, such as contact line and velocity slip. In this paper detailed methods and results are described for the study of Santos and Kawaji [1] on the comparison of experimental results and numerical modeling. The system studied consisted of a rectangular microchannel Tjunction nominally 100 μm in hydraulic diameter, used to generate Taylor slugs from air-water perpendicular flow. The effect of flow rates on parameters such as slug length, velocity slip, void fraction and two-phase frictional pressure drop were studied. Numerical simulation was performed using FLUENT volume-of-fluid (VOF) model. It is proposed in this paper that this microfluidic problem be taken up by researchers in the field as a benchmark case to test other numeric codes in comparison to FLUENT on the prediction of micro-scale multiphase flow, and also to model in more detail the experimental system described to obtain greater accuracy in prediction of microfluidic slug formation.

Discussions of Influence of some Factors on New Vehicle Absorption Cold Source

2014 ◽  
Vol 532 ◽  
pp. 479-482
Author(s):  
Hai Jun Qiao ◽  
Jia Nan Wu
Keyword(s):  
Lithium Bromide ◽  
Two Phase ◽  
Air Conditioners ◽  
Spray Process ◽  
Source Characteristics ◽  
Vof Model ◽  
Cold Source ◽  
Small Absorption ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

Small absorption cold source for car air conditioners differs from the compression cold source characteristics of the cold source, such as vehicle shaking can cause problems such as pollution of coolant water. Based on computational fluid dynamics (CFD) method, spray process in a new small cold source of lithium bromide absorption chiller was simulated by using the k-epsilon model and volume of fraction (VOF) model, which can capture the free surface of the two phase of liquid and gas, and the effects of nozzle profile and car bumping are analyzed, providing a theoretical basis for the application of a small absorption cold source for automotive.

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