Experimental Study of Bubble Dynamics and Concentration Variation in the Presence of Boron in the Liquid

2002 ◽  
Author(s):  
W. Jia ◽  
V. K. Dhir
Keyword(s):  
Bubble Dynamics ◽  
Concentration Field ◽  
Nucleation Site ◽  
Single Bubble ◽  
Boron Compounds ◽  
Measured Concentration ◽  
Neutron Absorber ◽  
Concentration Variation ◽  
Water Reactors ◽  
Miniature Sensor

Accumulation of neutron absorber (boron or boron compounds) within the porous crud layer on the fuel rods in the cores of pressured water reactors (PWR) results in the so-called axial offset anomaly (AOA). There is practically little information on the gradients of neutron absorber concentration near a nucleation site on the cladding surface during the growth of a bubble. The objective of the present work is to study bubble dynamics and associated concentration field of aqueous boron. As a first step in solving the complete problem, dynamics of single bubble was studied under pool boiling conditions. Distilled water and an aqueous solution containing 3,000ppm by weight of boric acid were used as test liquids. Single bubble was generated at a micro-fabricated cavity on a polished silicon wafer. It was found that the growth and departure processes of single bubbles are similar for both the test liquids. A miniature sensor for measurement of concentration was developed and calibrated. Concentration variation near the liquid-vapor interface was detected successfully. The measured concentration variations at different radial locations from the center of cavity have the same trend as given by the numerical simulations but the magnitude is much smaller.

Numerical Investigation of Single Bubble Dynamics Passing a Mesh-Based Structure

2020 ◽  
Author(s):  
Fadi Alnaimat ◽  
Bobby Mathew ◽  
Omar Alhammadi
Keyword(s):  
Bubble Dynamics ◽  
Cfd Simulation ◽  
Single Bubble ◽  
Separation Mechanism ◽  
Mesh Structure ◽  
Flow Restriction ◽  
Complex Interactions ◽  
Vof Model ◽  
Single Bubble Dynamics ◽  
Physical Features

Abstract In this article, investigations of the dynamic behaviors of a single bubble flowing across a mesh-based structure domain was conducted using the volume of fluid (VOF) model. The study was investigated in various mesh structure sizes, including hole size and gap distance. The fundamental behavior of bubble deformation and the effects of gap sizes were analyzed. Subsequently, the predicted dynamics of the deforming bubble area and the effect of the surface tension were examined inside the mesh holes. The discharging bubbles from the mesh structure resulted in a slight difference in the physical features from the original bubble dynamics before entering the mesh (flow restriction). This drafted the bubbles in different trajectories and led to behave differently based on the mesh characteristics. The complex interactions and the subsequent deformations were observed between different mesh sizes. For the validation of the bubble dynamics, the results of computational fluid dynamics (CFD) simulation were tested under different mesh sizes detailing the velocity field, exiting trajectory, bubbles deformation, and residence time, which helps to reveal the affected parameters on the separation mechanism of the original bubble.

Review on Bubble Dynamics in Microchannel Heat Sink

2019 ◽  
Author(s):  
Sambhaji T. Kadam ◽  
Ibrahim Hassan ◽  
Ritunesh Kumar ◽  
Aziz Rahman
Keyword(s):  
Bubble Growth ◽  
Bubble Dynamics ◽  
Growth Models ◽  
Flow Boiling ◽  
Nucleation Site ◽  
Bubble Nucleation ◽  
Operating Conditions ◽  
Geometrical Parameters ◽  
Detailed Knowledge ◽  
Diffusion Controlled

Abstract Inception of the boiling, in pool or flow boiling, is the formation of the vapour bubble at active nucleation site. The bubble dynamics plays an important role in the boiling process. It is critical as it unfolds many facets especially when channel size is reduced to submicron. The detailed knowledge of the bubble dynamics is helpful in establishing the thermal and hydraulic flow behaviour in microchannel. In this paper, the bubble dynamics which include bubble nucleation at nucleation site, its growth, departure and motion along the flow in a microchannel are discussed in details. Different models are developed for the critical cavity radius are compiled and observed that they show large variation when compare. The bubble growth models are compiled and concluded that a development of more generalized bubble growth model is necessary to account for the inertia controlled and thermal diffusion controlled regions. The bubble at the nucleation site in a microchannel grows under the influence of various forces such as surface tension, inertia, shear, gravitational and evaporation momentum. Parametric variations of these forces are critically studied and reckoned that the slope of these forces seems to be reduced beyond 500 μm. Eventually, possible impact of the various factors such as operating conditions, geometrical parameters, and thermophysical properties of fluid on bubble dynamics in microchannel has been reported.

Nonlinear Phenomena in Rayleigh-Plesset Equations for Single Bubble Dynamics

2011 ◽  
Author(s):  
Shohei Shikada ◽  
Hiroaki Yoshimura ◽  
Jiachun Li ◽  
Song Fu
Keyword(s):  
Bubble Dynamics ◽  
Single Bubble ◽  
Nonlinear Phenomena ◽  
Single Bubble Dynamics
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