scholarly journals Comparison of Components and Parameters of Some Sulfide Minerals Surface Tension with Regards to Stability of Mineral-Air Bubble System

2020 ◽  
Author(s):  
Bronisław Jańczuk ◽  
Anna Zdziennicka
Keyword(s):  
Surface Tension ◽  
Sulfide Minerals ◽  
Air Bubble ◽  
Bubble System

The motion of large bubbles in horizontal channels

1970 ◽  
Vol 43 (2) ◽  
pp. 247-255 ◽  
Author(s):  
G. C. Gardner ◽  
I. G. Crow
Keyword(s):  
Surface Tension ◽  
Experimental Investigation ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Phase Interface ◽  
Bubble Velocity ◽  
Radius Of Curvature ◽  
Channel Depth ◽  
Two Phase ◽  
Air Bubble

An experimental investigation of a large long air bubble moving into stationary water in a horizontal channel of rectangular cross-section is presented and three well-defined flow régimes for the water discharged beneath the bubble are described. The influence of surface tension on the bubble velocity is explained using the hypothesis that the radius of curvature of the two-phase interface close to the upper wall does not vary greatly with channel depth and is close to the theoretical value for a channel of such depth that the bubble is just motionless.

Mili-Scale Visualization of Bubble Growth-Translation and Droplet Impact Dynamics

2006 ◽  
Vol 128 (8) ◽  
pp. 736-736 ◽  
Author(s):  
R. M. Manglik ◽  
M. A. Jog ◽  
A. Subramani ◽  
K. Gatne
Keyword(s):  
Surface Tension ◽  
Video Processing ◽  
High Speed ◽  
Digital Video ◽  
Capillary Tube ◽  
Droplet Impact ◽  
Stainless Steel Surface ◽  
Air Bubble ◽  
Processing Software ◽  
The Impact

The dynamic behavior of an air bubble, emanating from a 0.32 mm i.d., 0.64 mm o.d., vertical capillary-tube orifice with a bubble interval of 0.22–0.28 s at constant pressure and adiabatic (T=25°C) conditions, as well as droplet impact and spreading on a hydrophobic surface are characterized. Images of the mili-scale spatial-temporal evolution of bubbles (embryonic appearance at orifice tip → growth and detachment → translation) as well as droplets were acquired using a high-speed (5000 frames/s) digital video camera fitted with a 8× optical zoom lens. It was triggered through a computer interface to record continuous high-speed video from which any desired frame can be captured by digital-video-processing software; the equivalent departure diameter was estimated by area-averaging using image processing software. The impact, spreading, and recoil behaviors of ethanol and water droplets on a horizontal stainless steel surface are depicted in Fig. 1. For constant Weber number (We∼10), the spreading and recoil dynamics in the two cases are significantly different. Higher wettability of ethanol promotes greater spreading and dampens recoil in comparison with that seen in water. Figure 2 depicts the growth of an air bubble in pools of ethanol and water. While displaying similar ebullience, a bubble of smaller size and surface age is produced in low-surface-tension ethanol. Dynamic shape variations of the air bubble as it translates upwards in the pool are seen in Fig. 3. From a nearly spherical, tear-drop bubble, the shape changes to an oblate ellipsoid during translation, and surface tension effects are manifest only in the size of respective bubbles.

The Effect of Surface Tension on Bubble Generation in Gas-Sheared Liquid Films

2019 ◽  
Author(s):  
João Vasques ◽  
Abubakr Ibrahim ◽  
David Hann ◽  
Kathy Simmons ◽  
Michael Walsh
Keyword(s):  
Surface Tension ◽  
Liquid Phase ◽  
Lower Surface ◽  
Liquid Films ◽  
Engine Oil ◽  
Air Bubbles ◽  
Bubble Generation ◽  
Air Bubble ◽  
Oil Films ◽  
Effect Of Surface

Abstract In the bearings of an aero-engine, oil is supplied not only for lubrication, but mostly for cooling, where heat is removed from the hot walls of the chambers by the oil films that are formed there. Based on prior work, it is observed that air bubbles can become trapped within liquid films potentially affecting fluid behavior. This paper reports on experiments conducted in a horizontal rectangular duct, where the liquid phase was sheared by a strong gas stream. In this configuration, air bubbles are seen to be entrapped in a similar manner to what was observed within prior bearing chamber visualization research. Of particular interest in this paper, is the effect of surface tension on air bubble generation in the liquid phase and its consequences for appropriate oil selection criteria. The surface tension was controlled by testing solutions with reduced surface tension by up to 47% of that of water, while maintaining the density and viscosity parameters constant. The results were obtained using a Brightness-Based Laser-Induced Fluorescence technique. Results show that reducing surface tension leads to a higher number of bubbles being generated, thus increasing the level of aeration of the liquid phase. Additionally, the velocity of the bubbles was also measured and seen to be lower for the lower surface tension cases.

A study on air bubble wetting: Role of surface wettability, surface tension, and ionic surfactants

2017 ◽  
Vol 410 ◽  
pp. 117-125 ◽  
Author(s):  
Jijo Easo George ◽  
Santhosh Chidangil ◽  
Sajan D. George
Keyword(s):  
Surface Tension ◽  
Surface Wettability ◽  
Ionic Surfactants ◽  
Air Bubble

scholarly journals Sistem Monitoring Air Bubble System Pada Prototype Sephull Bubble Vessel

2019 ◽  
Vol 4 (2) ◽  
pp. 55
Author(s):  
Mochammad Nasir ◽  
Miftah ◽  
M. Ali Mudhoffar
Keyword(s):  
Pressure Sensor ◽  
Analog Input ◽  
Air Bubble ◽  
Bubble System ◽  
Analog Output

Sephull Bubble Vessel adalah kapal dengan pelumasan udara yaitu kapal dengan injeksi udara di bagian bawahnya, disain kapal ini untuk mendapatkan sebuah kapal dengan kemampuan berlayar dengan kecepatan tinggi dengan konsumsi bahan bakar yang minimal. Untuk mendapatkan performance yang optimal, maka tekanan pada air bubble system harus diatur pada tekanan optimal yang dapat menghasilkan sistem pelumasan udara yang menghasilkan kinerja optimal. Untuk mendapatkan tekanan optimal perlu dilakukan uji coba air bubble system pada beberapa variasi tekanan, kecepatan kapal dan posisi air bubble system. Dalam kesempatan ini akan dirancang Sistem MonitoringAir bubble system pada Prototype Sephull Bubble Vessel, dengan menggunakanPressure sensor Autonics PSA-1. pressure sensor ini mampu mengukur tekanan sampai 10 bar. Analog Output sensor akan dijadikan input pada Analog Input NI-USB 6216 yang akan merubah signal analog sensor menjadi sinyal digital sehingga data tersebut dapat disimpan dalam sebuah file dengan menggunakan program akuisisi data dengan program LabView.Keywords : Pressure Sensor; Air Bubble system; NI-USB 6216.

scholarly journals Gas–Liquid Mass Transfer around a Rising Bubble: Combined Effect of Rheology and Surfactant

Fluids ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 84
Author(s):  
Gaelle Lebrun ◽  
Feishi Xu ◽  
Claude Le Men ◽  
Gilles Hébrard ◽  
Nicolas Dietrich
Keyword(s):  
Mass Transfer ◽  
Surface Tension ◽  
Sharp Decrease ◽  
Air Bubble ◽  
Hydrodynamic Parameters ◽  
Rising Bubble ◽  
Planar Laser ◽  
Liquid Mass Transfer ◽  
Experimental Values ◽  
Triton X

The influence of viscosity and surface tension on oxygen transfer was investigated using planar laser-induced fluorescence with inhibition (PLIF-I). The surface tension and the viscosity were modified using Triton X-100 and polyacrylamide, respectively. Changes in the hydrodynamic parameters of millimetric bubbles were identified, and transfer parameters were calculated. The results revealed a decrease in the mass transferred in the presence of a contaminant. For modified viscosity, the decrease in mass transferred was allowed for by current correlations, but the presence of surfactant led to a sharp decrease in the liquid side mass transfer coefficient, which became even lower when polymer was added. An explanation for the gap between classical correlations and experimental values of kL is discussed, and a hypothesis of the existence of an accumulation of contaminant in the diffusion layer is proposed. This led to the possibility of a decrease in the diffusion coefficient and oxygen saturation concentration in the liquid film, explaining the discrepancy between models and experience. Adapted values of DO2 and [O2] * in this layer were estimated. This original study unravels the complexity of mass transfer from an air bubble in a complex medium.

scholarly journals Spreading or contraction of viscous drops between plates: single, multiple or annular drops

2021 ◽  
Vol 925 ◽  
Author(s):  
H.K. Moffatt ◽  
Howard Guest ◽  
Herbert E. Huppert
Keyword(s):  
Surface Tension ◽  
Outer Boundary ◽  
Complete Separation ◽  
Small Perturbations ◽  
Air Bubble ◽  
Trapped Air ◽  
Viscous Drops ◽  
Fingering Instability ◽  
Pressure Region ◽  
Viscous Drop

The behaviour of a viscous drop squeezed between two horizontal planes (a squeezed Hele-Shaw cell) is treated by both theory and experiment. When the squeezing force $F$ is constant and surface tension is neglected, the theory predicts ultimate growth of the radius $a\sim t^{1/8}$ with time $t$. This theory is first reviewed and found to be in excellent agreement with experiment. Surface tension at the drop boundary reduces the interior pressure, and this effect is included in the analysis, although it is negligibly small in the squeezing experiments. An initially elliptic drop tends to become circular as $t$ increases. More generally, the circular evolution is found to be stable under small perturbations. If, on the other hand, the force is reversed ($F<0$), so that the plates are drawn apart (the ‘contraction’, or ‘lifting plate’, problem), the boundary of the drop is subject to a fingering instability on a scale determined by surface tension. The effect of a trapped air bubble at the centre of the drop is then considered. The annular evolution of the drop under constant squeezing is still found to follow a ‘one-eighth’ power law, but this is unstable, the instability originating at the boundary of the air bubble, i.e. the inner boundary of the annulus. The air bubble is realised experimentally in two ways: first by simply starting with the drop in the form of an annulus, as nearly circular as possible; and second by forcing four initially separate drops to expand and merge, a process that involves the resolution of ‘contact singularities’ by surface tension. If the plates are drawn apart, the evolution is still subject to the fingering instability driven from the outer boundary of the annulus. This instability is realised experimentally by levering the plates apart at one corner: fingering develops at the outer boundary and spreads rapidly to the interior as the levering is slowly increased. At a later stage, before ultimate rupture of the film and complete separation of the plates, fingering spreads also from the boundary of any interior trapped air bubble, and small cavitation bubbles appear in the very low-pressure region, far from the point of leverage. This exotic behaviour is discussed in the light of the foregoing theoretical analysis.

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