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.

Visual Observations of Chamber Volume Effect on Ebullience From Submerged Orifice Plates

2016 ◽  
Author(s):  
Sanjivan Manoharan ◽  
Milind A. Jog ◽  
Raj M. Manglik
Keyword(s):  
Surface Tension ◽  
Bubble Growth ◽  
High Speed ◽  
Capillary Tube ◽  
Volume Effect ◽  
Orifice Plate ◽  
Orifice Diameter ◽  
Chamber Volume ◽  
Acrylic Glass ◽  
Liquid Pools

Effect of chamber volume upstream of the orifice on ebullience from orifice plates is studied experimentally in this paper. Bubble growth from orifice plates submerged in liquid pools is captured using high speed videography. The orifice plate substrate is acrylic glass and 11 different orifice diameters (diameter range: 0.610< D0< 2.261mm) are utilized. In addition to water, ethanol-water binary mixture with surface tension of 54 mN/m is used to examine the interplay between surface tension and chamber volume effects on bubble characteristics. For an acrylic glass orifice plate with a fixed chamber volume, above a certain transition orifice diameter, the bubbles from the orifice plate are of the same size and shape as those from a capillary tube orifice. However, below this diameter, the bubbles from the orifice plate show significantly different characteristics due to the chamber volume effect. The bubbles are more spherical in shape with the apex being sharper and more pointed. The bubbles also tend to sit closer to the plate due to their abnormally large size while the growth times are much shorter. These differences are highlighted by comparing photographs of bubble growth with and without the chamber volume effect. Additionally, for the medium chamber region, an empirical correlation was proposed to predict bubble departure diameters to within ±15 %. For a fixed chamber volume, variation in surface tension showed no change in the transition orifice diameter.

Characteristics of Nucleation and Bubble Growth During Microscale Boiling

2005 ◽  
Author(s):  
Yong Tian ◽  
Jiang-Tao Liu ◽  
Xiao-Feng Peng
Keyword(s):  
Bubble Growth ◽  
High Speed ◽  
Bubble Dynamics ◽  
Ccd Camera ◽  
Initial Position ◽  
Length Scale ◽  
Formation Theory ◽  
Nucleus Formation ◽  
Microlayer Evaporation ◽  
Parallel Microchannels

In this paper, both nucleus formation and bubble growth during boiling in microchannels were investigated. A series of visualized experiments were conducted to observe the boiling nucleation and bubble dynamics restricted within parallel microchannels on a silicon wafer. The channels were rectangular and had selected length scale ranging from 50 to 100 microns. A high-speed CCD camera was employed together with a microscope to dynamically record the boiling images. The rates of bubble growth were measured in the channels. The phase change nucleus formation theory was used to determine the initial position of the bubble. The bubble growth rate was described by two ordinary differential equations deduced from the microlayer evaporation theory. The calculation and experimental results were reasonably coincided.

Force Analysis of Bubble Dynamics in Flow Boiling Silicon Nanowire Microchannels

2016 ◽  
Author(s):  
Tamanna Alam ◽  
Wenming Li ◽  
Fanghao Yang ◽  
Ahmed Shehab Khan ◽  
Yan Tong ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Bubble Growth ◽  
Bubble Dynamics ◽  
Flow Boiling ◽  
Silicon Nanowire ◽  
Bubble Nucleation ◽  
Force Analysis ◽  
Vapor Interface ◽  
Liquid Vapor

In microchannel flow boiling, bubble nucleation, growth and flow regime development are highly influenced by channel cross-section and physical phenomena underlying this mechanism are far from being well-established. Relative effects of different forces acting on wall-liquid and liquid-vapor interface of a confined bubble play an important role in heat transfer performances. Therefore, fundamental investigations are necessary to develop enhanced microchannel heat transfer surfaces. Force analysis of vapor bubble dynamics in flow boiling Silicon Nanowire (SiNW) microchannels has been performed based on theoretical, experimental and visualization studies. The relative effects of different forces on flow regime, instability and heat transfer performances of flow boiling in Silicon Nanowire microchannels have been identified. Inertia, surface tension, shear, buoyancy, and evaporation momentum forces have significant importance at liquid-vapor interface as discussed earlier by several authors. However, no comparative study has been done for different surface properties till date. Detailed analyses of these forces including contact angle and bubble flow boiling characteristics have been conducted in this study. A comparative study between Silicon Nanowire and Plainwall microchannels has been performed based on force analysis in the flow boiling microchannels. In addition, force analysis during instantaneous bubble growth stage has been performed. Compared to Plainwall microchannels, enhanced surface rewetting and critical heat flux (CHF) are owing to higher surface tension force at liquid-vapor interface and Capillary dominance resulting from Silicon Nanowires. Whereas, low Weber number in Silicon Nanowire helps maintaining uniform and stable thin film and improves heat transfer performances. Moreover, force analysis during instantaneous bubble growth shows the dominance of surface tension at bubble nucleation and slug/transitional flow which resulted higher heat transfer contact area, lower thermal resistance and higher thin film evaporation. Whereas, inertia force is dominant at annular flow and it helps in bubble removal process and rewetting.

Computational Modeling of Dynamics of Single Bubbles Emanating From Capillary-Tube Orifice in an Isothermal Liquid Pool

2008 ◽  
Author(s):  
S. K. Kasimsetty ◽  
R. M. Manglik ◽  
M. A. Jog
Keyword(s):  
Stokes Equations ◽  
Capillary Tube ◽  
Growth Dynamics ◽  
Liquid Pool ◽  
Navier Stokes ◽  
Equivalent Diameter ◽  
Navier Stokes Equations ◽  
Parametric Effects ◽  
Complete Set ◽  
Modeling Of Dynamics

The growth dynamics (inception → departure) of isolated gas bubbles, emanating from a capillary-tube orifice submerged in isothermal pools of different liquids is computationally investigated. The complete set of continuity and transient Navier-Stokes equations are solved, and the gas-liquid interface during the bubble growth process is tracked using a volume of fluid (VOF) method. Computational solutions that describe the dynamic behavior — incipience, growth, and pre-departure necking — of a single bubble growing from tips of sub-millimeter-to-millimeter-scale capillary orifices in stagnant pools are presented. The parametric effects of liquid properties (surface tension and viscosity, in particular), capillary diameters, and air flow rates on the bubble shape, its equivalent diameter, and growth times are described. Furthermore, these results are shown to be in excellent agreement with the available experimental data, and they fundamentally highlight the ebullience structure and the role of liquid-gas interfacial tension on the bubble evolution.

scholarly journals Dynamics of bubble growth during boiling at microgravity

2021 ◽  
Vol 2119 (1) ◽  
pp. 012170
Author(s):  
F Ronshin ◽  
A Sielaff ◽  
L Tadrist ◽  
P Stephan ◽  
O Kabov
Keyword(s):  
Heat Transfer ◽  
Bubble Growth ◽  
Boiling Heat Transfer ◽  
Bubble Dynamics ◽  
Heated Surface ◽  
Space Station ◽  
Growth Dynamics ◽  
Special Focus ◽  
Transfer Processes ◽  
Microgravity Conditions

Abstract The purpose of this investigation is to study the mechanisms of boiling heat transfer in microgravity conditions. The RUBI (Reference mUltiscale Boiling Investigation) is an experiment where the basic phenomena of boiling heat transfer processes on a heated surface are investigated on the ISS (International Space Station). The special focus is paid to the coupling of macroscopic bubble dynamics from nucleation, growth and detachment combined with the microscopic phenomena in the thin films and micro layers on the heater, underneath the boiling bubbles. The image treatment program has been developed in order to extract the bubble volume as well as the contact angle from the experimental images. The first data of the bubble growth dynamics have been obtained and analysed.

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.

Effects of Liquid Viscosity on Bubble Growth From Submerged Orifice Plates

2017 ◽  
Author(s):  
Sanjivan Manoharan ◽  
Milind A. Jog ◽  
Raj M. Manglik
Keyword(s):  
Bubble Growth ◽  
High Speed ◽  
Bubble Dynamics ◽  
Pure Water ◽  
Air Flow ◽  
Low Flow ◽  
Glycerol Solution ◽  
Stainless Steel Capillary ◽  
Flow Rates ◽  
Water Glycerol

Experimental investigation of bubble growth from orifice plates submerged in pools of viscous liquids has been carried out using high speed videography. Conflicting effects of viscosity on ebullience have been reported in the literature. These are addressed in the present study and their range of applicability has been identified. Furthermore, the effects of chamber volume on bubble dynamics in viscous media are examined. Orifice plates made of Acrylic glass (a hydrophilic surface) with varying orifice diameters from 0.813 mm to 1.500 mm, have been utilized. Additionally, bubble dynamics from a stainless steel capillary nozzle was captured and compared with that from orifice plates. The six different liquid pools were used, viz., pure distilled water, ethylene glycol, propylene glycol, and three different aqueous glycerol solutions. The aqueous glycerol solutions varied in viscosity from 48 cP to 128 cP. The flow rate was regulated such that the isolated bubble regime was encountered. For the smaller orifices, viscosity effects were present at all flow rates and the bubbles in water-glycerol solutions were much larger than those in pure water. However, for the larger orifice sizes, water-glycerol solutions produced bubbles that were larger than those in water only at high air flow rates. For larger orifice sizes, at low flow rates, there was no increase in bubble size in highly viscous water-glycerol solutions compared to pure water. In fact, with 1.5 mm diameter plate orifice, the bubbles for 128 cP water-glycerol solution were smaller than those in pure water at low air flow rates. When chamber effects were present, the bubbles in the more viscous medium differed in shape and size from those in pure water.

scholarly journals Dynamics of bubble growth under a heated substrate

2021 ◽  
Vol 2119 (1) ◽  
pp. 012134
Author(s):  
D Y Kochkin ◽  
A S Mungalov ◽  
I A Derevyannikov
Keyword(s):  
Bubble Growth ◽  
Buoyancy Force ◽  
Bubble Dynamics ◽  
Bubble Diameter ◽  
Growth Dynamics ◽  
Heating Power ◽  
Gas Bubble ◽  
Shadow Method ◽  
Heated Substrate ◽  
Heating Plate

Abstract This paper investigates the growth dynamics of a vapor-gas bubble pressed against a heating plate by the buoyancy force. The shadow method was used to capture images, which were then automatically processed to calculate the size of the bubble. As expected, the bubble dynamics significantly depends on the heating power. It was found that the ratio of bubble diameter to bubble height increases as it grows.

The Effects of Bubble Interface Contamination on Bubble Motion, Bubble-Induced Surrounding Liquid Motion and Mass Transfer

2015 ◽  
Author(s):  
Yuki Iburi ◽  
Jie Huang ◽  
Takayuki Saito
Keyword(s):  
Mass Transfer ◽  
Surface Tension ◽  
High Speed ◽  
Bubble Surface ◽  
Dissolution Process ◽  
Contaminated Water ◽  
Equivalent Diameter ◽  
Liquid Motion ◽  
High Speed Video ◽  
Surrounding Liquid

Mass transfer from a bubble to the surrounding liquid plays an important role in chemical engineering processes. To improve the efficiency and safety of the processes, a deep understanding of the mass transfer mechanism from bubbles to the surrounding liquid is essential. In the present study, we examined a CO2 single bubble of 2∼3 mm in equivalent diameter that ascended zigzag in purified water and contaminated water (500ppm 1-pentanol solution). We used a high speed video camera systems with high spatial and temporal resolution, for visualization of the bubble wake and bubble-induced surrounding liquid motion. The dissolution process of CO2 from the bubble to the surrounding liquid was visualized via LIF/HPTS (Laser Induced Fluorescence) method. HPTS, which is a fluorescent substance, was excited by Ar ion laser with a wavelength of 458 nm, then emitted with a wavelength of 513 nm. A pH level of CO2 solution decreased with increase in CO2 concentration; hence the emission intensity of HPTS was reduced. As a result, dark regions observed below the bubble rear accorded with the bubble wakes; from visualization of this bubble wakes through the high speed video cameras, dynamic CO2 dissolution process was obtained. In the purified water, the bubble shape was oblate ellipsoid, and horse-shoe-like vortices were formed in the rear of the bubble. On the other hand, in the contaminated water, the bubble was nearly spherical. Furthermore, behavior of the vortices changed. These different results in two conditions were caused by the decrease in the surface tension owing to the bubble surface contamination. While the bubble was rising, the non-uniform distribution of the surfactant on the bubble surface occurred. Hence, a gradient of the surface tension was formed on the bubble surface, furthermore, it caused the Marangoni convection. Meanwhile, in order to consider the relationship between dissolution process and the surrounding liquid motion, we measured the liquid phase velocities via PIV.

Bubble Characteristics During Boiling in Microchannels

2005 ◽  
Author(s):  
Jiang-Tao Liu ◽  
Yong Tian ◽  
Xiao-Feng Peng
Keyword(s):  
Bubble Growth ◽  
High Speed ◽  
Bubble Dynamics ◽  
Solid Wall ◽  
Ccd Camera ◽  
Vapor Bubbles ◽  
Experimental Conditions ◽  
Boiling Process ◽  
Parallel Microchannels ◽  
Bubble Characteristics

A series of visualized experiments were conducted to investigate the boiling nucleation and bubble dynamics restricted within parallel microchannels on a silicon chip. The cross-section of each channel was 100 μm (W) × 100 μm (H). A high-speed CCD camera (up to 8,000 fps) was employed together with a microscope to record the boiling process. Under the present experimental conditions, the incipience of boiling was captured. The rates of bubble growth were measured at various flow and heating conditions. The interaction between vapor bubbles, vapor-liquid interface, and solid wall, was analyzed.

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