Theoretical Modeling and Experimental Measurements of Single Bubble Dynamics From a Submerged Orifice in a Liquid Pool

2007 ◽  
Author(s):  
S. K. Kasimsetty ◽  
A. Subramani ◽  
R. M. Manglik ◽  
M. A. Jog
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Bubble Dynamics ◽  
Bubble Diameter ◽  
Liquid Pool ◽  
Orifice Diameter ◽  
Equivalent Diameter ◽  
Bubble Behavior ◽  
Balance Of Forces ◽  
Submerged Orifice

The dynamics of a single gas bubble, emanating from a submerged orifice in stagnant water has been explored both theoretically and experimentally. The mathematical model represents a fundamental balance of forces due to buoyancy, viscosity, surface tension, liquid inertia, and gas momentum transport, and the consequent motion of the gas-liquid interface. Theoretical solutions describe the dynamic bubble behavior (incipience, growth and necking) as it grows from a tip of a sub-millimeter-scale capillary orifice in an isothermal pool of water. These results are also found to be in excellent agreement with a set of experimental data that are obtained from optical high-speed micro-scale flow visualization. Variations in bubble shape, equivalent diameter, and growth times with capillary orifice diameter and air flow rates are outlined. These parametric trends suggest a two-regime ebullient transport: (a) a constant volume regime where the bubble diameter is not affected by the flow rate, and (b) a growing bubble regime where bubble size increases with flow rate.

Correlations of Bubble Diameter and Frequency for Air–Water System Based on Orifice Diameter and Flow Rate

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Hasan B. Al Ba'ba'a ◽  
Tarek Elgammal ◽  
Ryoichi S. Amano
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Bubble Diameter ◽  
Water System ◽  
Correlation Factor ◽  
Orifice Diameter ◽  
Clean Water ◽  
Bubble Frequency ◽  
Air Bubble ◽  
The Mean

Prediction correlations of air bubble diameter and frequency in stagnant clean water were established. Eleven different orifice diameters were tested under flow rate of 0.05–0.15 SLPM. The resulted bubble size and frequency were traced using high-speed camera. It was found that the mean Sauter diameter and bubble frequency are in the range of 3.7–6.9 mm and 6.4–47.2 bubbles per second, respectively. Nonlinear regression was performed to design the new correlations of estimating diameter and frequency with a correlation factor of 0.93 and 0.94, respectively. Flow rate and orifice size had the highest impact on the studied parameters.

Experimental Study of Single-Bubble Dynamics in Isothermal Liquid Pools: Effects of Fluid Properties, Orifice Diameter and Flow Rate

2007 ◽  
Author(s):  
A. Subramani ◽  
M. A. Jog ◽  
R. M. Manglik
Keyword(s):  
Surface Tension ◽  
Flow Rate ◽  
High Speed ◽  
Bubble Dynamics ◽  
Processing System ◽  
Single Bubble ◽  
Orifice Diameter ◽  
Growth Time ◽  
Interfacial Behavior ◽  
Fluid Properties

The dynamics of a single bubble as it grows at and eventually detaches from the tip of submerged capillary orifices in isothermal pools of pure liquids of varying fluid properties is studied experimentally. The transient interfacial behavior around the evolving isolated bubble (from inception through growth, necking, and detachment) is mapped by means of optical micro-scale flow visualization that uses a high-speed high-resolution digital camera and image processing system. Parametric effects of capillary orifice diameter (do = 0.32, 1.0, and 1.76 mm), air flow rate (2 ≤ Q˙ ≤ 20 ml/min), and liquid properties (surface tension and viscosity), on the bubbling signature (growth time, departure diameter, and bubble interval) are explored and highlighted. It is found that bubble evolution, in a first order scaling, can be correlated by a balance of forces due to buoyancy, viscosity, surface tension, liquid inertia, and gas momentum transport at the transient gas-liquid interface.

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.

Bubble Dynamics From Artificial Nucleation Sites During Subcooled Pool Boiling

2009 ◽  
Author(s):  
Xipeng Lin ◽  
David M. Christopher ◽  
Yanshen Li ◽  
Hui Li
Keyword(s):  
High Speed ◽  
Bubble Dynamics ◽  
Stokes Equations ◽  
Liquid Pool ◽  
Numerical Results ◽  
Bottom Surface ◽  
Heating Rates ◽  
Bubble Generation ◽  
Vof Model ◽  
Nucleation Sites

The bubble dynamics of ethanol vapor bubbles growing, coalescing and condensing in a subcooled ethanol liquid pool were investigated experimentally and numerically for a range of subcoolings and heating rates. The bubbles were generated from an artificial pair of nucleation sites made of microscale tubes mounted flush with the bottom surface of the liquid pool with the vapor supplied by a vapor generator. Observations of the bubble generation with a high speed camera show the various coalescence modes with no coalescence at low heating rates and high subcoolings and horizontal and/or vertical coalescence depending on the heating rate and subcooling. At very low subcoolings, the bubbles grew quite large with various types of coalescence. The numerical results using solutions of the Navier-Stokes equations with the VOF model and using a simplified one dimensional model also describe the bubble dynamics and the conditions for coalescence. The numerical results suggest that the condensation rate at the interface is probably much higher than predicted by the model due to significant convection in the liquid pool or due to significant disturbance of the interface by the vapor jet entering the bubble.

Experimental Visualization of Two Phase Flow Inside an Electrical Submersible Pump Stage

2009 ◽  
Author(s):  
Lissett Barrios ◽  
Mauricio Gargaglione Prado
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubble Diameter ◽  
Phase Flow ◽  
Submersible Pump ◽  
Bubble Behavior ◽  
Two Phase ◽  
Operational Conditions ◽  
Electrical Submersible Pump

Dynamic multiphase flow behavior inside a mixed flow Electrical Submersible Pump (ESP) has been studied experimentally and theoretically for the first time. The overall objectives of this study are to determine the flow patterns and bubble behavior inside the ESP and to predict the operational conditions that cause surging. An experimental facility has been designed and constructed to enable flow pattern visualization inside the second stage of a real ESP. Special high speed instrumentation was selected to acquire visual flow dynamics and bubble size measurements inside the impeller channel. Experimental data was acquired utilizing two types of tests (surging test and bubble diameter measurement test) to completely evaluate the pump behavior at different operational conditions. A similarity analysis performed for single-phase flow inside the pump concluded that viscosity effects are negligible compared to the centrifugal field effects for rotational speeds higher than 600 rpm. Therefore, the two-phase flow tests were performed for rotational speeds of 600, 900, 1200, and 1500 rpm. Results showed formation of a large gas pocket at the pump intake during surging conditions.

Bubble Behavior and Mean Diameter in Subcooled Flow Boiling

1996 ◽  
Vol 118 (1) ◽  
pp. 110-116 ◽  
Author(s):  
O. Zeitoun ◽  
M. Shoukri
Keyword(s):  
Heat Flux ◽  
Mass Flux ◽  
High Speed ◽  
Flow Boiling ◽  
Bubble Diameter ◽  
Image Processing Technique ◽  
Bubble Behavior ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
The Mean

Bubble behavior and mean bubble diameter in subcooled upward flow boiling in a vertical annular channel were investigated under low pressure and mass flux conditions. A high-speed video system was used to visualize the subcooled flow boiling phenomenon. The high-speed photographic results indicated that, contrary to the common understanding, bubbles tend to detach from the heating surface upstream of the net vapor generation point. Digital image processing technique was used to measure the mean bubble diameter along the subcooled flow boiling region. Data on the axial area-averaged void fraction distributions were also obtained using a single-beam gamma densitometer. Effects of the liquid subcooling, applied heat flux, and mass flux on the mean bubble size were investigated. A correlation for the mean bubble diameter as a function of the local subcooling, heat flux, and mass flux was obtained.

Experimental Visualization of Two-Phase Flow Inside an Electrical Submersible Pump Stage

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Lissett Barrios ◽  
Mauricio Gargaglione Prado
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Bubble Diameter ◽  
Phase Flow ◽  
Submersible Pump ◽  
Bubble Behavior ◽  
Two Phase ◽  
Operational Conditions ◽  
Electrical Submersible Pump

Dynamic multiphase flow behavior inside a mixed flow electrical submersible pump (ESP) has been studied experimentally and theoretically for the first time. The overall objectives of this study are to determine the flow patterns and bubble behavior inside the ESP and to predict the operational conditions that cause surging. An experimental facility has been designed and constructed to enable flow pattern visualization inside the second stage of a real ESP. Special high-speed instrumentation was selected to acquire visual flow dynamics and bubble size measurements inside the impeller channel. Experimental data were acquired utilizing two types of tests (surging test and bubble diameter measurement test) to completely evaluate the pump behavior at different operational conditions. A similarity analysis performed for single-phase flow inside the pump concluded that viscosity effects are negligible compared to the centrifugal field effects for rotational speeds higher than 600 rpm. Therefore, the two-phase flow tests were performed for a rotational speeds of 600, 900, 1200, and 1500 rpm. Results showed formation of a large gas pocket at the pump intake during surging conditions.

Altering Bubble Dynamics via Vapor Extraction

2014 ◽  
Author(s):  
Randall G. Fox ◽  
Corey D. Juarez ◽  
Deborah V. Pence ◽  
James A. Liburdy
Keyword(s):  
High Speed ◽  
Bubble Dynamics ◽  
Heated Surface ◽  
Bubble Diameter ◽  
Nucleation Site ◽  
Vapor Extraction ◽  
High Speed Imaging ◽  
Conduction Model ◽  
Gap Height ◽  
Surface Bubble

Bubble dynamics in the presence of a porous confining surface through which vapor is extracted was experimentally investigated. Using a pulsed laser operating at 3500 pulses per second (pps), bubbles were generated at a single, 30 μm diameter nucleation site in a silicon disk. A time-averaged heat flux of 80 W/cm2 and a constant pressure differential of 35 kPa across a porous surface were maintained. The surface, a supported porous Teflon® membrane, has a nominal porosity of 55% and pore diameter of 0.45μm. Steady-state heating was achieved as determined from a one-dimensional conduction model yielding a dimensionless surface temperature fluctuations of less than 0.01%. Bubble diameter and frequency were determined using high-speed imaging for ten gap heights ranging between 0.52 mm and 3.99 mm, where the gap height is defined as the distance between the heated surface and the confining surface. Bubble dynamics of freely departing, coalescing, and rupturing bubbles are considered. Results are compared to diameters and frequencies achieved in unconfined (i.e. pool boiling) conditions. Isolated bubble dynamics depend on gap height and can be grouped into three ranges: greater than, equal to, and less than the bubble diameters for unconfined conditions, which for the present conditions is 1.53 mm. This paper is a work in progress.

Computational and Experimental Characterization of Single Bubble Dynamics in Isothermal Liquid Pools

2007 ◽  
Author(s):  
A. Subramani ◽  
S. K. Kasimsetty ◽  
R. M. Manglik ◽  
M. A. Jog
Keyword(s):  
Surface Tension ◽  
Bubble Growth ◽  
High Speed ◽  
Bubble Dynamics ◽  
Great Influence ◽  
Growth Dynamics ◽  
Equivalent Diameter ◽  
Parametric Effects ◽  
Liquid Pools ◽  
Visualization Techniques

The process of bubble growth is of great influence on the bubble volume and bubble rise velocity. The overall behavior of bubbles at fluid interfaces depends strongly on bubble growth and the closely linked process of bubble detachment. In the present study, the dynamics of a single gas bubble emanating from an orifice submerged in isothermal liquid pools is investigated computationally and experimentally. The parametric effects of liquid properties, capillary diameters and air flow rates on the bubble shape, equivalent diameter, and growth times on the dynamic behavior (incipience, growth and necking) of air bubbles, in fluids of varying surface tension and viscosity, as it grows from a tip of a sub-millimeter-scale capillary orifice have been studied. Computational solutions have been obtained by solving the complete set of governing equations using Volume of Fluid (VOF) interface tracking method. The CFD model has been verified experimentally using optical high speed micro-scale flow visualization techniques. The results were analyzed in a theoretical stand point considering the various forces acting on the bubble such as forces due to buoyancy, viscosity, surface tension, liquid inertia, and gas momentum transport, and the consequent motion of the gas-liquid interface. The results obtained ascertain the role of liquid-gas interfacial forces as well as the fluid properties on the bubble growth dynamics.

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