Bubble Behavior in Molten Glass in a Temperature Gradient

1981 ◽  
Vol 9 ◽  
Author(s):  
M. Meyyappan ◽  
R. S. Subramanian ◽  
W. R. Wilcox ◽  
H. Smith
Keyword(s):  
Temperature Gradient ◽  
Molten Glass ◽  
Bubble Diameter ◽  
Sodium Borate ◽  
Gas Bubble ◽  
Bubble Motion ◽  
Reduced Gravity ◽  
Bubble Behavior ◽  
Rocket Experiment

ABSTRACTGas bubble motion in a temperature gradient was observed in a sodium borate melt in a reduced gravity rocket experiment under the NASA SPAR program. Large bubbles tended to move faster than smaller ones, as predicted by theory. When the bubbles contacted a heated platinum strip, motion virtually ceased because the melt only imperfectly wets platinum. In some cases bubble diameter increased noticeably with time.

Experimental Observation of the Thermocapillary Driven Motion of Bubbles in a Molten Glass Under Low Gravity Conditions

1981 ◽  
Vol 9 ◽  
Author(s):  
H. D. Smith ◽  
D. M. Mattox ◽  
W. R. Wilcox ◽  
R. S. Subramanian ◽  
M. Meyyappan
Keyword(s):  
Temperature Gradient ◽  
Molten Glass ◽  
Hot Spot ◽  
Fused Silica ◽  
Sodium Borate ◽  
Bubble Behavior ◽  
Low Gravity ◽  
Thermocapillary Force ◽  
Silica Cell ◽  
Theoretical Predictions

ABSTRACTTheory and ground based studies of bubble behavior in a fluid in the presence of a temperature gradient strongly indicate the action of a thermocapillary force which causes the bubbles to move. This'phenomenon been considered in the traditional treatments of glass fining. To demonstrate that the observed motion conformed to theoretical prediction it was necessary to perform the experiment under low gravity conditions. NASA's SPAR program provided an excellent opportunity to do this.A sodium borate melt containing a specific bubble array was subjected to a well defined temperature gradient for more than 4 minutes. The sample was contained in a platinum/ fused-silica cell which permitted photographic coverage of the experiment. Photographs were taken at one second intervals during the course of the experiment. They clearly show that the bubbles move toward the hot spot on the platinum heater strip. The observed motion is consistent with the theoretical predictions for the temperature gradients parallel and perpendicular to the heater strip.

scholarly journals Bubble Behavior on Horizontal and Vertical Carbon Anode Surfaces in Cryolite Melt Applying a See-Through Cell

2021 ◽  
Vol 3 (1) ◽  
pp. 8
Author(s):  
Nikolina Stanic ◽  
Espen Sandnes
Keyword(s):  
Current Density ◽  
Bubble Diameter ◽  
Vertical Surface ◽  
Visual Observation ◽  
Anode Surface ◽  
Large Bubble ◽  
Carbon Anode ◽  
Gas Bubble ◽  
Bubble Behavior

Gas bubble behavior on a carbon anode in a cryolite melt has been studied by visual observation using a see-through cell. The bubble phenomena studied have included growth, coalescence, and detachment during electrolysis. Two different anode designs were tested, an anode with a horizontal facing-downwards surface and an anode with a vertical surface. At the horizontal anode, it was found that one large bubble was formed by the growth and coalescence of smaller bubbles, and finally, the large bubble detached periodically. For the vertical anode surface, many smaller bubbles were formed and detached randomly. The bubble diameter was decreasing with increasing current density for both anodes.

Bubble Breakup Phenomena in a Venturi Tube

2007 ◽  
Author(s):  
A. Fujiwara ◽  
K. Okamoto ◽  
K. Hashiguchi ◽  
J. Peixinho ◽  
S. Takagi ◽  
...  
Keyword(s):  
High Speed ◽  
Bubbly Flow ◽  
Bubble Diameter ◽  
Pressure Change ◽  
Venturi Tube ◽  
Large Bubble ◽  
Breakup Process ◽  
Bubble Behavior ◽  
Bubble Breakup ◽  
Unstable Surface

Microbubble generation techniques have been proposed in former investigations. Here, we study an effective technique using air bubbly flow into a convergent-divergent nozzle (venturi tube). Pressure change in the diverging section induces bubble breakup. The purpose of this study is to clarify the effect of flow velocity at the throat with respect to the bubble breakup process and the bubble behavior in a venturi tube. Relations between generated bubble diameter and bubble breakup process are also described. Using high speed camera for detailed observation of bubble behavior, the following features were obtained. The velocity at the throat is expected to be of the order of the magnitude of the speed of sound of bubbly flow and a drastic bubble expansion and a shrink is induced. Besides, a liquid column appeared after the bubble flowing into the throat, and it grew up to stick to the bubble like in the form of a jet. This jet induced both unstable surface waves and the breakup of a single large bubble into several pieces.

Numerical Simulation and Experimental Validation of the Dynamics of a Single Bubble During Pool Boiling Under Constant and Time-Varying Reduced Gravity Conditions

2003 ◽  
Author(s):  
H. S. Abarajith ◽  
D. M. Qiu ◽  
V. K. Dhir
Keyword(s):  
Numerical Simulation ◽  
Heated Surface ◽  
Bubble Diameter ◽  
Pool Boiling ◽  
Growth Period ◽  
Single Bubble ◽  
Time Varying ◽  
Reduced Gravity ◽  
System Pressure ◽  
Vapor Liquid

The numerical simulation and experimental validations of the growth and departure of a single bubble on a horizontal heated surface during pool boiling under reduced gravity conditions have been performed here. A finite difference scheme is used to solve the equations governing mass, momentum and energy in the vapor liquid phases. The vapor-liquid interface is captured by level set method, which is modified to include the influence of phase change at the liquid-vapor interface. The effects of reduced gravity conditions, wall superheat and liquid subcooling and system pressure on the bubble diameter and growth period have been studied. The simulations are also carried out under both constant and time-varying gravity conditions to benchmark the solution with the actual experimental conditions that existed during the parabolic flights of KC-135 aircraft. In the experiments, a single vapor bubble was produced on an artificial cavity, 10 μm in diameter microfabricated on the polished silicon wafer, the wafer was heated electrically from the back with miniature strain gage type heating elements in order to control the nucleation superheat. The bubble growth period and the bubble diameter predicted from the numerical simulations have been found to compare well with the data from experiments.

Gas bubble growth and detachment under reduced gravity

1990 ◽  
Vol 58 (2) ◽  
pp. 137-142
Author(s):  
G. M. Gladchenko ◽  
Yu. A. Kirichenko ◽  
K. V. Rusanov
Keyword(s):  
Bubble Growth ◽  
Gas Bubble ◽  
Reduced Gravity

A Theoretical Study on Air Bubble Motion in a Centrifugal Pump Impeller

1980 ◽  
Vol 102 (4) ◽  
pp. 446-453 ◽  
Author(s):  
Kiyoshi Minemura ◽  
Mitsukiyo Murakami
Keyword(s):  
Centrifugal Pump ◽  
Equations Of Motion ◽  
Bubble Diameter ◽  
Inertia Force ◽  
Air Bubbles ◽  
Bubble Motion ◽  
Pump Impeller ◽  
Air Bubble ◽  
Surrounding Liquid ◽  
Centrifugal Pump Impeller

Equations of motion for air bubbles in a centrifugal pump impeller were obtained and solved numerically for a flow in a radial-flow-type impeller, and the results were compared with experiments. Governing factors for the bubble motion are the force due to the pressure gradient, the drag force due to the flow resistance of the surrounding liquid, and the inertia force due to virtual mass of the liquid. If the bubble diameter is reduced continuously, the effect of the inertia force is also reduced and trajectories of the air bubbles approach more and more to the path of the flowing water.

Self-Propelled Sliding Bubble Motion Induced by Surface Microstructure in Pool Boiling of a Dielectric Fluid Under Microgravity

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Naveenan Thiagarajan ◽  
Sushil H. Bhavnani ◽  
Vinod Narayanan
Keyword(s):  
Vapor Bubble ◽  
Bubble Dynamics ◽  
Heated Surface ◽  
Pool Boiling ◽  
Bubble Nucleation ◽  
Radius Of Curvature ◽  
Dielectric Fluid ◽  
Bubble Motion ◽  
Reduced Gravity ◽  
Modification Technique

This paper reports bubble dynamics observed during pool boiling over microstructures with an asymmetric saw-tooth cross section, under reduced gravity. The periodic saw-toothed ratchets etched on a silicon surface include fabricated vapor bubble nucleation sites only on the shallow slope. Reduced gravity pool boiling experiments were conducted aboard a Boeing 727 aircraft carrying out parabolic maneuvers. The fluid used was FC-72, a highly wetting dielectric fluid used as a coolant for electronics. Under microgravity, it was observed that the bubble diameters were six times larger than in terrestrial gravity. Also, self-propelled sliding bubble motion along the surface of the saw teeth was observed in reduced gravity. The velocity of the sliding bubbles across the saw teeth, following lateral departure from the cavities, was measured to be as high as 27.4 mm/s. A model for the sliding bubble motion is proposed by attributing it to the force due to pressure differences that arise in the liquid film between the vapor bubble and the saw-toothed heated surface. The pressure difference is due to difference in the radius of curvature of the interface between the crest and trough of the saw teeth. The surface modification technique, which resulted in the sliding bubble motion, has the potential to alleviate dry-out caused due to stagnant vapor bubbles over heat sources under microgravity when the buoyancy forces are negligible compared to the surface tension forces.

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