Modeling bubble evolution in air-oil mixture with a simplified method

2016 ◽  
Vol 230 (16) ◽  
pp. 2865-2871 ◽  
Author(s):  
Junjie Zhou ◽  
Jibin Hu ◽  
Shihua Yuan
Keyword(s):  
Mass Transfer ◽  
Bubble Dynamics ◽  
Bubble Radius ◽  
Pressure Change ◽  
Isothermal Transformation ◽  
Adiabatic Process ◽  
Interphase Mass Transfer ◽  
Simplified Method ◽  
Bubble Evolution ◽  
Model C

This work addresses the problem of bubble evolution arising from gas cavitation in hydraulic oils. Two significant aspects, including the interphase mass transfer represented by air release and absorption phenomena and different thermodynamic considerations, are currently taken into account using a simplified method. In particular, three new models in progressive relationship are proposed on the basis of Rayleigh–Plesset equation which describes bubble dynamics. They are Model A in which air content is assumed to be constant, Model B in which the interphase mass transfer is introduced with the air undergoing an isothermal transformation, and Model C assuming an adiabatic process for the bubble evolution. With the goal of investigating the effects of these aspects, comparisons of the three models for two typical cases are presented with regard to the practical circumstances in which the oil pressure is set to increase linearly or oscillate sinusoidally. Results show a consistent trend for both cases concerning Model B and Model C compared to Model A. Although its speed relates to many factors, air release and absorption has a relevant impact on gas bubble radius. By the reason of adiabatic assumption, Model C provides a slower response regarding the oil pressure change. However, Model B and Model C may be both inaccurate if considering the actual interfacial heat transfer. In this viewpoint, the oil temperature in fluid power system could be affected.

Numerical Study on Mass Transfer Effects on Spherical Cavitation Bubble Collapse in an Acoustic Field

2010 ◽  
Author(s):  
Ehsan Samiei ◽  
Mehrzad Shams ◽  
Reza Ebrahimi
Keyword(s):  
Mass Transfer ◽  
Cavitation Bubble ◽  
Bubble Dynamics ◽  
Numerical Study ◽  
Bubble Radius ◽  
Numerical Code ◽  
Bubble Collapse ◽  
Growth Time ◽  
Transfer Effects ◽  
Low Amplitude

A numerical code to simulate mass transfer effects on spherical cavitation bubble collapse in an acoustic pressure domain in quiescent water has been developed. Gilmore equation is used to simulate bubble dynamics, with considering mass diffusion and heat transfer. Bubbles with different initial radii were considered in quiescent infinite water in interaction with sinusoidal shock waves with different magnitudes of amplitude and frequency. Simulations were done in two cases; with and without considering mass transfer. Good agreement with reference data was achieved. For bubbles with small radii in high frequency pressure field with low amplitude, mass transfer causes larger maximum radii and growth time, and more violent resultant collapse. Decreasing pressure frequency or increasing its amplitude causes larger maximum radii, longer collapse time, and more violent collapse. But, in cases with mass transfer because at the last moments of collapse stage a large amount of water vapor is trapped inside the bubble, the collapse will become less violent. For larger bubbles collapse becomes more violent for the cases without mass transfer in all pressure amplitudes and higher frequencies. But decreasing pressure frequency makes the collapse of the bubbles with mass transfer more violent. However, mass transfer effects decreases with increasing initial bubble radius.

scholarly journals Investigation of Cavitation Bubble Dynamics Considering Pressure Fluctuation Induced by Slap Forces

Mathematics ◽  
2021 ◽  
Vol 9 (17) ◽  
pp. 2064
Author(s):  
Xiaoyu Wang ◽  
Shenghao Zhou ◽  
Zumeng Shan ◽  
Mingang Yin
Keyword(s):  
Pressure Fluctuation ◽  
Negative Pressure ◽  
Bubble Dynamics ◽  
Bubble Radius ◽  
Shock Pressure ◽  
Standoff Distance ◽  
Vibration Velocity ◽  
Solid Boundary ◽  
Initial Radius ◽  
Bubble Evolution

Cavitation erosion is induced by the penetrating pressure from implosion of cavitation bubbles nearby solid boundary. The bubble evolution and the subsequent collapse pressure are especially important to evaluate the erosion degradation of solid boundary materials. The bubble dynamics equation taking into account the influence of distance between bubble and solid boundary is formulated to investigate the effect of boundary wall on bubble evolution process. The pressure fluctuation induced by slapping forces is adopted to evaluate the bubble dynamic characteristics. Negative pressure period which reflects the effect of vibration velocity and gap clearance also has large influence on bubble dynamics. The effects of standoff distance, initial radius and negative pressure period on bubble evolution and collapsing shock pressure are discussed. Maximum bubble radius increases with standoff distance and initial radius, while shock pressure increases with distance and decreases with bubble initial radius, and both of them increase with negative pressure period.

scholarly journals Bubble Dynamics in a Two-Phase Bubbly Mixture

2010 ◽  
Author(s):  
Arvind Jayaprakash ◽  
Sowmitra Singh ◽  
Georges Chahine
Keyword(s):  
Void Fraction ◽  
High Speed ◽  
Bubble Dynamics ◽  
Bubble Radius ◽  
Discharge Voltage ◽  
Large Bubble ◽  
Water Mixture ◽  
Two Phase ◽  
Mixture Density ◽  
Bubbly Medium

The dynamics of a primary relatively large bubble in a water mixture including very fine bubbles is investigated experimentally and the results are provided to several parallel on-going analytical and numerical approaches. The main/primary bubble is produced by an underwater spark discharge from two concentric electrodes placed in the bubbly medium, which is generated using electrolysis. A grid of thin perpendicular wires is used to generate bubble distributions of varying intensities. The size of the main bubble is controlled by the discharge voltage, the capacitors size, and the pressure imposed in the container. The size and concentration of the fine bubbles can be controlled by the electrolysis voltage, the length, diameter, and type of the wires, and also by the pressure imposed in the container. This enables parametric study of the factors controlling the dynamics of the primary bubble and development of relationships between the bubble characteristic quantities such as maximum bubble radius and bubble period and the characteristics of the surrounding two-phase medium: micro bubble sizes and void fraction. The dynamics of the main bubble and the mixture is observed using high speed video photography. The void fraction/density of the bubbly mixture in the fluid domain is measured as a function of time and space using image analysis of the high speed movies. The interaction between the primary bubble and the bubbly medium is analyzed using both field pressure measurements and high-speed videography. Parameters such as the primary bubble energy and the bubble mixture density (void fraction) are varied, and their effects studied. The experimental data is then compared to simple compressible equations employed for spherical bubbles including a modified Gilmore Equation. Suggestions for improvement of the modeling are then presented.

Correction to ‘Unsteady convective diffusion with interphase mass transfer’

1974 ◽  
Vol 341 (1626) ◽  
pp. 407-408 ◽  
Keyword(s):  
Mass Transfer ◽  
Convective Diffusion ◽  
Interphase Mass Transfer

In the above-specified paper (Sankarasubramanian & Gill 1973), equations (48 a ) and (75) should read I ( j, l ) = I ( l, j )= ∫ 1 0 y 3 J 0 ( μ j y ) J 0 ( μ l y d y = 2(2 β 2 + μ 2 j + μ 2 l / ( μ 2 j – μ 2 l ) 2 J 0 ( μ j ) J 0 ( μ l ) ( j ≠ l ), K 2 ≈ 1/( Pe ) 2 + 64(1+6/ β ) λ 2 1 Ʃ ∞ l =1 λ 2 l +1 / ( λ 2 l +1 – λ 2 1 ) 5∙

Sign in / Sign up

Export Citation Format

Share Document