Vapor bubble growth with a high value of overheating

2007 ◽  
Vol 5 ◽  
pp. 85-90
Author(s):  
S.P. Aktershev ◽  
V.V. Ovchinnikov
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Satisfactory Agreement ◽  
Vapor Bubble ◽  
Bubble Growth ◽  
Bubble Dynamics ◽  
Bubble Radius ◽  
Temperature Inhomogeneity ◽  
Evaporation Front ◽  
Initial Stage

The numerical simulation of the growth of a vapor bubble in inhomogeneously heated liquid is performed; the influence of the temperature inhomogeneity on the bubble dynamics is investigated. The calculations are compared with experimental data for a vapor bubble growing on a cylindrical heater. At high overheating, the results of the calculations are in satisfactory agreement with experimental data for the initial stage of growth of the vapor bubble. In the presence of evaporation fronts, the measured bubble radius values exceed the calculated values. This excess can be explained by the inflow of vapor to the bubble from the evaporation front.

scholarly journals Growth and Collapse Dynamics of a Vapor Bubble near or at a Wall

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 12
Author(s):  
Huigang Wang ◽  
Chengyu Zhang ◽  
Hongbing Xiong
Keyword(s):  
Vapor Bubble ◽  
Bubble Growth ◽  
Solid Wall ◽  
Bubble Radius ◽  
Entropy Change ◽  
Growth Stages ◽  
Change Rate ◽  
Bubble Density ◽  
Particle Hydrodynamics ◽  
Vapor Mass

This study investigated the dynamics of vapor bubble growth and collapse for a laser-induced bubble. The smoothed particle hydrodynamics (SPH) method was utilized, considering the liquid and vapor phases as the van der Waals (VDW) fluid and the solid wall as a boundary. We compared our numerical results with analytical solutions of bubble density distribution and radius curve slope near a wall and the experimental bubble shape at a wall, which all obtained a fairly good agreement. After validation, nine cases with varying heating distances (L2 to L4) or liquid heights (h2 to h10) were simulated to reproduce bubbles near or at a wall. Average bubble radius, density, vapor mass, velocity, pressure, and temperature during growth and collapse were tracked. A new recognition method based on bubble density was recommended to distinguish the three substages of bubble growth: (a) inertia-controlled, (b) transition, and (c) thermally controlled. A new precollapse substage (Stage (d)) was revealed between the three growth stages and collapse stage (Stage (e)). These five stages were explained from the out-sync between the bubble radius change rate and vapor mass change rate. Further discussions focused on the occurrence of secondary bubbles, shockwave impact on the wall, system entropy change, and energy conversion. The main differences between bubbles near and at the wall were finally concluded.

Approximate Solution for the Heat Transfer Controlled Growth of a Steadily Translating Vapor Bubble

2008 ◽  
Author(s):  
Michael Shusser
Keyword(s):  
Heat Transfer ◽  
Approximate Solution ◽  
Vapor Bubble ◽  
Bubble Growth ◽  
Constant Velocity ◽  
Thermal Boundary Layer ◽  
Bubble Radius ◽  
Controlled Growth ◽  
Flow Models ◽  
Rate Comparison

Existing analytical solution for the problem of the heat transfer controlled growth of a spherical vapor bubble moving with a constant velocity under the assumptions of a thin thermal boundary layer and potential flow results in a complicated integral equation for the bubble radius and is too unwieldy to be used in multiphase flow models. The goal of this work is to suggest an approximate solution for this problem that gives correct asymptotic behavior and yields a simpler expression for the bubble growth rate. Comparison with the exact solution showed that this way a good approximation can be obtained.

Prediction Model for Bubble Contact Circle Diameter on Heating Wall

2010 ◽  
Author(s):  
De-qi Chen ◽  
Liang-ming Pan
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Bubble Growth ◽  
Bubble Radius ◽  
Growth Time ◽  
Heating Wall ◽  
Contact Circle ◽  
Proper Values ◽  
Circle Diameter ◽  
Contact Diameter

Phenomenal and theoretical analysis about the evolution of bubble contact circle diameter during bubble growing is presented in current paper; and it is found that bubble contact diameter is dependent on bubble growth rate and bubble radius strongly. By analyzing experimental data from open literature, the relation between dimensionless bubble contact diameter, kw, and dimensionless bubble growth time, t+, is obtained; based on this, a model relative to dimensionless bubble growth rate, dR+/dt+, and dimensionless bubble radius, R+, is proposed for prediction of bubble contact diameter. With proper values for coefficients, aw and nw, this model can well predict experimental data of bubble circle contact diameter in published literatures, with an error within ±20%.

Numerical Simulation of Bubble Dynamics in the Presence of Boron in the Liquid

2001 ◽  
Author(s):  
Qiang Bai ◽  
V. K. Dhir
Keyword(s):  
Numerical Simulation ◽  
Bubble Growth ◽  
Bubble Dynamics ◽  
Thin Liquid Film ◽  
Dynamic Change ◽  
Nucleate Boiling ◽  
Reactor Power ◽  
Vapor Interface ◽  
Fuel Rod ◽  
Liquid Vapor

Abstract Deposition of boron on the fuel rod cladding during boiling of water containing boron can depress the neutron flux and lead to a decrease in nuclear reactor power output. There is practically little precise information on the temperature field, the gradients of chemical concentration and deposition of boron on the cladding surface. The objective of the present work is to simulate the nucleate boiling process along with velocity, temperature and concentration fields of aqueous boron in the vicinity of the cladding of a fuel rod. As a first step in solving the complete problem, two-dimensional numerical simulation of a bubble growth on a horizontal surface is considered. A finite difference scheme is used to solve the equations governing conservation of mass, momentum, energy and species concentration. The calculation domain is divided into macro and micro regions. In macro-region, the governing equations are used to calculate the distributions of velocity, temperature, and concentration. The Level Set method is used to capture the evolving liquid-vapor interface. For micro-region, lubrication theory is used, which includes the disjoining pressure in the thin liquid film. The solutions for micro-region and macro-region are matched at the outer edge of the micro-layer. A dilute aqueous Boron solution is considered in the simulation. From numerical simulations, the dynamic change in concentration distribution of boron during the bubble growth shows that the precipitation of boron can occur near the advancing and receding liquid-vapor interface when the ambient boron concentration level is 0.003.

scholarly journals Modeling of vapor bubble growth at subatmospheric pressures

2021 ◽  
Vol 2039 (1) ◽  
pp. 012035
Author(s):  
I V Vladyko ◽  
I P Malakhov ◽  
A S Surtaev ◽  
A A Pil’nik ◽  
A A Chernov
Keyword(s):  
Experimental Data ◽  
Analytical Solution ◽  
Growth Model ◽  
Vapor Bubble ◽  
Bubble Growth ◽  
Numerical Calculations ◽  
Superheated Water ◽  
Thermal Growth ◽  
Simulation Results ◽  
Good Agreement

Abstract In this paper, the results of numerical calculations of a vapor bubble growth in superheated water at different pressures are presented. Modeling is based on a previously developed by the authors semi-analytical solution. The results are verified by experimental data obtained at atmospheric and subatmospheric pressures. The presented simulation results and experimental data are in good agreement. The advantage of the solution over the earlier ones (based on the thermal growth model) is shown.

A Simplified Model for Predicting Vapor Bubble Growth Rates in Heterogeneous Boiling

1995 ◽  
Vol 117 (4) ◽  
pp. 976-980 ◽  
Author(s):  
W. C. Chen ◽  
J. F. Klausner ◽  
R. Mei
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Vapor Bubble ◽  
Bubble Growth ◽  
Heating Surface ◽  
Simplified Model ◽  
Order Ordinary Differential Equation ◽  
Empirical Parameter ◽  
Wetting Fluids ◽  
Microlayer Evaporation

A simplified model, based on heat transfer through a wedge-shaped liquid microlayer and a lumped thermal analysis for a solid heater, is developed for predicting the vapor bubble growth rate in heterogeneous pool boiling. A first-order ordinary differential equation is obtained for the bubble growth rate. An empirical parameter, C2, which characterizes the region of the heating surface influenced by microlayer evaporation, is determined by matching the existing experimental data with the predicted growth rate. The present bubble growth model compares well with the available experimental data for intermediate and moderately wetting fluids in which Jacob number ranges from 0.52 to 1974.

scholarly journals Fibre-induced drag reduction

2008 ◽  
Vol 602 ◽  
pp. 209-218 ◽  
Author(s):  
J. J. J. GILLISSEN ◽  
B. J. BOERSMA ◽  
P. H. MORTENSEN ◽  
H. I. ANDERSSON
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Drag Reduction ◽  
Elastic Layer ◽  
Turbulent Drag Reduction ◽  
Rigid Polymer ◽  
Fibre Concentration ◽  
Induced Drag ◽  
Turbulent Drag

We use direct numerical simulation to study turbulent drag reduction by rigid polymer additives, referred to as fibres. The simulations agree with experimental data from the literature in terms of friction factor dependence on Reynolds number and fibre concentration. An expression for drag reduction is derived by adopting the concept of the elastic layer.

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