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Saturday, November 14, 2020 | History

3 edition of Bubble generation in a continuous liquid flow under gravity conditions found in the catalog.

Bubble generation in a continuous liquid flow under gravity conditions

Bubble generation in a continuous liquid flow under gravity conditions

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  • 31 Currently reading

Published by National Aeronautics and Space Administration, Glenn Research Center, National Technical Information Service, distributor in [Cleveland, Ohio], Springfield, VA .
Written in English

  • Microgravity.,
  • Two phase flow.,
  • Bubbles.,
  • Flow geometry.,
  • Flow velocity.,
  • Force distribution.,
  • Interfacial tension.,
  • Continuum flow.

  • Edition Notes

    StatementSalvatore Cezar Pais.
    Series[NASA contractor report] -- NASA/CR-1999-209170., NASA contractor report -- NASA CR-209170.
    ContributionsNASA Glenn Research Center.
    The Physical Object
    Pagination1 v.
    ID Numbers
    Open LibraryOL15557026M

    Compressible air flow through a collapsing liquid cavity. International Journal for Numerical Methods in Fluids, Vol. 67, Issue. 11, p. A. The effect of surface conditions of a sphere on its water-entry cavity. J. Appl. Bubble generation in quiescent and co-flowing liquids. International Journal of Heat and Mass Transfer, Vol.   Hi, I am trying to model the 2-D flow dyanmics of bubble column (gas-liquid flow) using FLUENT, however, I do not get right profile result of the Gas Hold-Up (Gas Volume Fraction). I am trying to work on the Half Domain model because the bubble column . Subscribe to the FLOW-3D blog to learn about upcoming CFD software developments, novel applications and featured customer case studies.

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Bubble generation in a continuous liquid flow under gravity conditions Download PDF EPUB FB2

Bubble Generation in a Continuous Liquid Flow Under Reduced Gravity Conditions The present work reports a study of bubble generation under reduced gravity conditions for both co-flow and cross-flow configurations.

Experiments were performed aboard the DC-9 Reduced Gravity Aircraft at NASA Glenn Research Center, using an air-water system. Bubble Generation in a Continuous Liquid Flow Under. Bubble generation in a continuous liquid flow under gravity conditions. [Cleveland, Ohio]: Springfield, VA: National Aeronautics and Space Administration, Glenn Research Center ; National Technical Information Service, distributor.

MLA Citation. Pais, Salvatore Cezar. and NASA Glenn Research Center. dioxide driven bubble formation upon acidification of waters under some circumstances. Even if a source water is initially at equilibrium with the atmosphere and has no potential to form bubbles, the water can become supersaturated with carbon dioxide upon coagulant addition by conversion of bicarbonate to carbon dioxide: [HCO3-] + [H+] → [H File Size: KB.

the motion of bubbles and drops in reduced gravity Posted By Mary Higgins Clark Media Publishing TEXT ID cb5da Online PDF Ebook Epub Library arising from an imposed temperature gradient a water drop is always in the shape of a sphere although a falling drop may adopt various shapes because of various forces.

A few studies of bubble formation in reduced gravity conditions have been carried out in the past. Kim et al. () proposed that bubble detachment in the absence of buoyancy could only be achieved by the liquid flow drag, and hence a coflowing liquid was the primary controlling factor for bubble generation in microgravity.

In the present work, bubble generation and detachment via wall injection is experimentally studied in order to understand the underlying physical process that governs bubble detachment under low-gravity conditions and in the presence of liquid cross-flow.

The gas flow rates considered in this study fall in the quasi-static regime. Under shear flow conditions, the bubble growth is affected by an additional tangential force that originates from the drag force created by the liquid flow.

Since this drag force acts in the opposite direction to the tangential component of the buoyancy force, the bubble can move downstream or upstream Bubble generation in a continuous liquid flow under gravity conditions book the growth depending on the.

This book is intended as a combination of a reference book for those who work with cavitation or bubble dynamics and as a monograph for advanced students interested in some of the basic problems associated with this category of multi-phase flows.

A book like this has many roots. It. As flow is velocity multiplied by pipe area, changing the pipe cross sectional area (a Bubble generation in a continuous liquid flow under gravity conditions book or smaller pipe) will cause a change in velocity. This becomes useful when selecting a pipe size or in negative pressure conditions, page 5.

Water at Rest. When no water is flowing in a gravity. The formation of gas bubbles and their subsequent rise due to buoyancy are very important fundamental phenomena that contribute significantly to the hydrodynamics in gas−liquid reactors.

The rise of a bubble in dispersion can be associated with possible coalescence and dispersion followed by its disengagement from the system. The phenomenon of bubble formation decides the primitive bubble. • Bubbly flow: discrete gaseous bubbles in a continuous liquid. • Droplet flow: discrete fluid droplets in a continuous gas.

• Particle-laden flow: discrete solid particles in a continuous fluid. • Slug flow: large bubbles in a continuous liquid. • Annular flow: continuous liquid along walls, gas in core.

• Stratified and free. Single frames from the two video cameras were analyzed to determine the bubble size GAS-LIQUID FLOW AT MICROGRAVITY CONDITIONS--I 60 60 50 50 40 40 3o a0 "6 20 20 10 10 0 0 3 5 d(mm) outlet 3 5 7 9 d (mm) Figure 9. Bubble size distribution in 0g flow: ULS = m/s; U~s = m/s.

distribution. It is predicted by this model that bubble volume increases under constant flow conditions and a bubble does not detach from a nozzle when the gas flow rate is small in a quiescent liquid.

In Fig. 6, one can see the specific breakup rates calculated nearly under the same conditions as those, used for Fig. 5, but at much higher turbulence energy dissipation rate, ε = 40 W k g. In this case, the bubble size range, where the specific breakup rate of a rising bubble exceeds that of a bubble under microgravity conditions, does not exist.

Bubble formation in flowing liquids was investigated experimentally under reduced gravity conditions. The effects of gas flow rate, liquid flow velocity, and liquid flow direction on bubble formation were studied for a period of s under reduced gravity conditions produced in the 10 m drop tower at the Hokkaido National Industrial Research Institute at Sapporo in Hokkaido.

Dissertation: Bubble Generation in a Continuous Liquid Flow under Reduced Gravity Conditions. Advisor: Simon Ostrach. No students known. If you have additional information or corrections regarding this mathematician, please use the update form. Numerical Simulations of Gas-Liquid Flow Dynamics in Bubble Columns Abstract There is great potential for using computational fluid dynamics (CFD) as a tool in scale-up and design of bubble columns.

Full-scale experimentation in bubble columns is expensive and CFD is an alternative approach to study bubble column hydrodynamics.

An understanding of the behaviour of two phase fluids flow in zero gravity conditions is in the continuous phase fluid. of a single bubble in stagnant liquid under zero-gravity condition. the bubble size. Some representative images of bubble generation are shown in the below table along with flow conditions.

The N 2 gas flow rate is estimated to be less than 1 µL/min. The flow rate of water varies between to 5 µL/min. There are limits to the size of stable bubbles with a strong dependence on the channel depth. The formation of gas bubbles and their subsequent rise due to buoyancy are very important fundamental phenomena that contribute significantly to the hydrodynamics in gas-liquid reactors.

The rise of a bubble in dispersion can be associated with possible coalescence and dispersion followed by its disengagement from the system. The phenomenon of bubble formation decides the primitive bubble size. Experimental studies and numerical simulations of the single bubble growth and departure mechanisms under low gravity have been conducted.

An artificial cavity of 10 μm in diameter was made on the polished Silicon wafer. The back surface of the wafer was electrically heated in order to control the surface nucleation superheat.

The experiments were performed during the parabola flights of the. The model is validated with measurements on a benchmark experiment of liquid-metal argon flow in a laboratory-scale system.

() Drag coefficients of single bubbles under normal and micro gravity conditions. JSME Int J Ser B – Google Scholar. Yang H, Thomas BG () Multiphase flow and bubble size distribution in continuous. The bubble generation rate also the bubble at the orifice mouth becomes asymmetric due to the drag force created by the liquid flow.

Under non-wetting conditions, the bubble can slide over the. Vapor-Gas Bubble Evolution and Growth in Extremely Viscous Fluids Under Vacuum Formation of vapor and gas bubbles and voids is normal and expected in flow processes involving extremely viscous fluids in normal gravity.

Practical examples of extremely viscous fluids are epoxy-like filler materials before the epoxy fluids cure to their permanent form to create a mechanical bond between two. Salvatore Cezar Pais is an American aerospace engineer and inventor who works at the Naval Air Station Patuxent patent applications on behalf of his employers have attracted international attention for their potential military and energy-producing applications, but also doubt about their feasibility, and speculation that they may be misinformation intended to mislead the United.

interfacial forces in the laminar bubbly flow regime. They predicted a clear bubble plume and a time-dependent, multiple staggered vortex mode of circulation that characterizes the liquid bed of the bubble column. The computed flow structure qualitatively compared with the experimentally observed flow.

The objective of the present work is to experimentally investigate the effects of liquid cross-flow velocity, gas flow rate, and orifice diameter on bubble formation in a wall-bubble injection configuration.

Data were taken mainly under reduced gravity conditions but some data were taken in normal gravity. So the main point is to model the flow when gas (compressible and high velocity) and water mix in a T- junction.

From, my initial studies i have used VOF method of FLUENT, but not able to generate. However, bubbles are expected to present to a certain extent the effects of gas circulation under different conditions, as in diluted solutions (Astarita and Apuzzo, ).

This contribution focuses on the study of the dynamics of bubbles in liquid for systems in which bubbles. This contribution presents different approaches for the modeling of gas entrainment under water by a plunging jet. Since the generation of bubbles happens on a scale which is smaller than the bubbles, this process cannot be resolved in meso-scale simulations, which include the full length of the jet and its environment.

This is why the gas entrainment has to be modeled in meso-scale simulations. Dynamic Micro-bubble Generator for Water Processing and Cleaning Applications Abstract The micro-bubble technology in water is widely known and effectively used, but the fundamental mechanisms of the micro-bubble generation and characteristics are not clearly established.

Virtually all data to date regarding parametric effects of gravity on pool boiling have been inferred from experiments performed in low-g ⁠, 1 g ⁠, or g current work is based on observations of boiling heat transfer obtained over a continuous range of gravity levels (0 g – g) under subcooled liquid conditions (⁠ n-perfluorohexane, Δ T sub = 26 ° C ⁠, and 1.

We study the shape and motion of gas bubbles in a liquid flowing through a horizontal or slightly inclined thin annulus. Experimental data show that in the horizontal annulus, bubbles develop a unique ‘tadpole-like’ shape with a semi-circular cap and a highly stretched tail.

Keyword: Two-phase bubble flow, liquid phase velocity and large diameter horizontal pipe flow. INTRODUCTION Liquid velocity plays an important role in the physical modeling of both single and two-phase flow. If a liquid is the continuous phase of a flowing mixture, knowledge of its velocity.

There are three types of boundaries in the model domain. Channel/airway walls are modeled with no-slip conditions, a parabolic velocity profile with a mean velocity of U was specified at the inlet and outlet such that the inlet and outlet flow rate are equivalent and the air–liquid interface is modeled as a free surface boundary with a surface tension γ.

bubble column operates in the bubble flow regime (highly viscous liquid phase or non-Newtonian liquids are exceptional), • The height-to-diameter ratio is in the range of for the air. Flow Regimes Trickle bed reactors operate in a variety of flow regimes ranging from gas-continuous to liquid-continuous patterns.

They usually fall into two broad categories referred to as low interaction regime (trickle flow regime) and high interaction regime (pulse, spray, bubble and dispersed bubble flow regimes). Bubble flow is defined as a Two-Phase Flow where small bubbles are dispersed or suspended as discrete substances in a liquid continuum.

Typical features of this flow are moving and deformable interfaces of bubbles in time and space domains and complex interactions between the interfaces, and also between the bubbles and the liquid flow.

liquid(water) up-flow bubble column by CFD analysis. CFD simulation of bubble column reactor: Bubble columns are gas-liquid reactors where liquid forms. a continuous phase and gas flows in the form of dispersed bubbles, the bubbles are injected from the center of the inlet surface in the simulation domain.

The bubble trajectory is. behaviour of a continuous chain of bubbles under different operating conditions. For the first time computational intensive 3D volume-of-fluid simulations have been performed with comparatively larger laboratory scale bubble column (D = 20 cm, H = 1 m).

The VOF approach implemented in the commercial code for.A siphon (from Ancient Greek: σίφων, "pipe, tube", also spelled nonetymologically syphon) is any of a wide variety of devices that involve the flow of liquids through a narrower sense, the word refers particularly to a tube in an inverted "U" shape, which causes a liquid to flow upward, above the surface of a reservoir, with no pump, but powered by the fall of the liquid as it.

The evolution of thermal and concentration fields and fluid flows was studied applying the interferometric method. In contrast to a thermocapillary convection representing a stationary flow and stable temperature distribution, the periodic concentration disturbances around the bubble were observed in the solutocapillary case.