Modelling of material pitting from cavitation bubble collapse

2014 ◽  
Vol 755 ◽  
pp. 142-175 ◽  
Author(s):  
Chao-Tsung Hsiao ◽  
A. Jayaprakash ◽  
A. Kapahi ◽  
J.-K. Choi ◽  
Georges L. Chahine
Keyword(s):  
Cavitation Bubble ◽  
Bubble Dynamics ◽  
Numerical Approach ◽  
Bubble Collapse ◽  
Material Surface ◽  
Collapse Pressure ◽  
Flow Solver ◽  
Incompressible Boundary ◽  
The Impact ◽  
Impulsive Pressure

AbstractMaterial pitting from cavitation bubble collapse is investigated numerically including two-way fluid–structure interaction (FSI). A hybrid numerical approach which links an incompressible boundary element method (BEM) solver and a compressible finite difference flow solver is applied to capture non-spherical bubble dynamics efficiently and accurately. The flow codes solve the fluid dynamics while intimately coupling the solution with a finite element structure code to enable simulation of the full FSI. During bubble collapse high impulsive pressures result from the impact of the bubble re-entrant jet on the material surface and from the collapse of the remaining bubble ring. A pit forms on the material surface when the impulsive pressure is large enough to result in high equivalent stresses exceeding the material yield stress. The results depend on bubble dynamics parameters such as the size of the bubble at its maximum volume, the bubble standoff distance from the material wall, and the pressure driving the bubble collapse. The effects of these parameters on the re-entrant jet, the following bubble ring collapse pressure, and the generated material pit characteristics are investigated.

Numerical Prediction of Impact Force in Cavitating Flows

2010 ◽  
Vol 132 (10) ◽  
Author(s):  
Hong Wang ◽  
Baoshan Zhu
Keyword(s):  
Numerical Method ◽  
Cavitation Bubble ◽  
Bubble Dynamics ◽  
Impact Force ◽  
Quantitative Agreement ◽  
Bubble Collapse ◽  
Cavitating Flows ◽  
Cavitation Model ◽  
Model Based ◽  
The Impact

A numerical method including a macroscopic cavitation model based on the homogeneous flow theory and a microscopic cavitation model based on the bubble dynamics is proposed for the prediction of the impact force caused by cavitation bubble collapse in cavitating flows. A large eddy simulation solver, which is incorporated with a macroscopic cavitation model, is applied to simulate the unsteady cavitating flows. Based on the simulated flow field, the evolution of the cavitation bubbles is determined by a microscopic cavitation model from the resolution of a Rayleigh–Plesset equation including the effects of the surface tension, the viscosity and compressibility of fluid, the thermal conduction and radiation, the phase transition of water vapor at the interface, and the chemical reactions. The cavitation flow around a hydrofoil is simulated to validate the macroscopic cavitation model. A good quantitative agreement is obtained between the prediction and the experiment. The proposed numerical method is applied to predict the impact force at cavitation bubble collapse on a KT section in cavitating flows. It is found that the shock pressure caused by cavitation bubble collapse is very high. The impact force is predicted qualitatively compared with the experimental data.

The Collapse of a Gas Bubble near a Solid Wall by a Shock Wave and the Induced Impulsive Pressure

1984 ◽  
Vol 198 (2) ◽  
pp. 81-86 ◽  
Author(s):  
A Shima ◽  
Y. Tomita ◽  
K Takahashi
Keyword(s):  
Shock Wave ◽  
Experimental Study ◽  
Cavitation Bubble ◽  
Solid Wall ◽  
Impact Pressure ◽  
Bubble Collapse ◽  
Gas Bubble ◽  
Bubble Interaction ◽  
The Impact ◽  
Impulsive Pressure

An experimental study concerning the shock wave—bubble interaction was conducted in order to obtain a unified consideration of the mechanism of the impulsive pressure generation induced by the cavitation bubble collapse. It was found that the relation between the maximum impulsive pressure, pG, max, and the relative distance, lc/Re, is closely similar to the known result obtained from a single spark-generated bubble, and that a gas bubble within the region of lc/Re ≤ 7 behaves as a source capable of generating more intensive impulsive pressure than the impact pressure induced by a shock wave impinging directly on a solid wall without the presence of a gas bubble.

Investigation on cavitation bubble dynamics induced by clinically available Ho:YAG lasers

2016 ◽  
Vol 5 (2) ◽  
Author(s):  
Karl Stock ◽  
Daniel Steigenhöfer ◽  
Thomas Pongratz ◽  
Rainer Graser ◽  
Ronald Sroka
Keyword(s):  
Cavitation Bubble ◽  
Bubble Dynamics ◽  
Laser Energy ◽  
Bubble Collapse ◽  
High Contrast ◽  
Core Diameter ◽  
Ho:Yag Laser ◽  
Fiber Core ◽  
Set Up ◽  
Short Time

AbstractEndoscopic laser lithotripsy is the preferred technique for minimally invasive destruction of ureteral and kidney stones, and is mostly performed by pulsed holmium:yttrium-aluminum-garnet (Ho:YAG) laser irradiation. The absorbed laser energy heats the water creating a vapor bubble which collapses after the laser pulse, thus producing a shock wave. Part of the laser energy strikes the stone through the vapor bubble and induces thermomechanical material removal. Aim of the present study was to visualize the behavior and the dynamics of the cavitation bubble using a specially developed ultra-short-time illumination system and then to determine important characteristics related to clinically used laser and application parameters for a more detailed investigation in the future.In accordance with Toepler’s Schlieren technique, in the ultra-short-time-illumination set-up the cavitation bubble which had been induced by Ho:YAG laser irradiation at the fiber end, was illuminated by two Q-switched lasers and the process was imaged in high contrast on a video camera. Cavitation bubbles were induced using different pulse energies (500 mJ/pulse and 2000 mJ/pulse) and fiber core diameters (230 μm and 600 μm) and the bubble dynamics were recorded at different times relative to the Ho:YAG laser pulse. The time-dependent development of the bubble formation was determined from the recordings by measuring the bubble diameter in horizontal and vertical directions, together with the volume and localization of the center of the bubble collapse.The results show that the bubble dynamics can be visualized and studied with both high contrast and high temporal resolution. The bubble volume increases with pulse energy and with fiber diameter. The bubble shape is almost round when a larger fiber core diameter is used, and elliptical when using a fiber of smaller core diameter. Moreover, the center of the resulting bubble is slightly further away from the fiber end and the center of the bubble collapse for a smaller fiber core diameter.The experimental set-up developed gives a better understanding of the bubble dynamics. The experiments indicate that the distance between fiber tip and target surface, as well as the laser parameters used have considerable impact on the cavitation bubble dynamics. Both the bubble dynamics and their influence on the stone fragmentation process require further investigation.

scholarly journals Cavitation and bubble dynamics: the Kelvin impulse and its applications

2015 ◽  
Vol 5 (5) ◽  
pp. 20150017 ◽  
Author(s):  
John R. Blake ◽  
David M. Leppinen ◽  
Qianxi Wang
Keyword(s):  
Cavitation Bubble ◽  
High Speed ◽  
Bubble Dynamics ◽  
Clinical Medicine ◽  
Bubble Collapse ◽  
Rigid Boundary ◽  
Design Problems ◽  
Practical Applications ◽  
Wide Range ◽  
Naval Engineering

Cavitation and bubble dynamics have a wide range of practical applications in a range of disciplines, including hydraulic, mechanical and naval engineering, oil exploration, clinical medicine and sonochemistry. However, this paper focuses on how a fundamental concept, the Kelvin impulse, can provide practical insights into engineering and industrial design problems. The pathway is provided through physical insight, idealized experiments and enhancing the accuracy and interpretation of the computation. In 1966, Benjamin and Ellis made a number of important statements relating to the use of the Kelvin impulse in cavitation and bubble dynamics, one of these being ‘One should always reason in terms of the Kelvin impulse, not in terms of the fluid momentum…’. We revisit part of this paper, developing the Kelvin impulse from first principles, using it, not only as a check on advanced computations (for which it was first used!), but also to provide greater physical insights into cavitation bubble dynamics near boundaries (rigid, potential free surface, two-fluid interface, flexible surface and axisymmetric stagnation point flow) and to provide predictions on different types of bubble collapse behaviour, later compared against experiments. The paper concludes with two recent studies involving (i) the direction of the jet formation in a cavitation bubble close to a rigid boundary in the presence of high-intensity ultrasound propagated parallel to the surface and (ii) the study of a ‘paradigm bubble model’ for the collapse of a translating spherical bubble, sometimes leading to a constant velocity high-speed jet, known as the Longuet-Higgins jet.

scholarly journals Experimental Study on the Impact Characteristics of Cavitation Bubble Collapse on a Wall

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1262 ◽  
Author(s):  
Jing Luo ◽  
Weilin Xu ◽  
Jun Deng ◽  
Yanwei Zhai ◽  
Qi Zhang
Keyword(s):  
Impact Strength ◽  
Cavitation Bubble ◽  
Measuring System ◽  
Critical Conditions ◽  
Bubble Collapse ◽  
Main Concern ◽  
Wall Surface ◽  
Cavitation Bubbles ◽  
Impact Area ◽  
The Impact

As a hydrodynamic phenomenon, cavitation is a main concern in many industries such as water conservancy, the chemical industry and medical care. There are many studies on the generation, development and collapse of cavitation bubbles, but there are few studies on the variation of the cyclic impact strength on walls from the collapse of cavitation bubbles. In this paper, a high-speed dynamic acquisition and analysis system and a pressure measuring system are combined to study the impact of a cavitation bubble generated near a wall for various distances between the cavitation bubble and the wall. The results show that (1) with the discriminating criteria of the impact pressure borne by the wall, the critical conditions for the generation of a micro-jet in the collapse process of the cavitation bubbles are obtained, and therefore collapses of cavitation bubbles near the wall are mainly divided into primary impact area collapses, secondary impact area collapses and slow release area collapses; (2) it can be seen from the impact strength of the cavitation bubble collapse on the wall surface that the impact of cavitation bubbles on the wall surface during the first collapse decreases as γ (the dimensionless distance between the cavitation bubble and the wall) increases, but the impact of the second collapse on the wall surface increases first and then decreases sharply. When γ is less than 1.33, the impact on the wall surface is mainly from the first collapse. When γ is between 1.33 and 2.37, the impact on the wall surface is mainly from the second collapse. These conclusions have potential theoretical value for the utilization or prevention and control technologies for cavitation erosion.

Development of a PVDF sensor array for measurement of the impulsive pressure generated by cavitation bubble collapse

2006 ◽  
Vol 41 (3) ◽  
pp. 365-373 ◽  
Author(s):  
Yi-Chun Wang ◽  
Ching-Hung Huang ◽  
Yung-Chun Lee ◽  
Ho-Hsun Tsai
Keyword(s):  
Cavitation Bubble ◽  
Sensor Array ◽  
Bubble Collapse ◽  
Impulsive Pressure

Numerical simulation of traveling bubble cavitation

2006 ◽  
Vol 16 (4) ◽  
pp. 393-416 ◽  
Author(s):  
Sunil Mathew ◽  
Theo G. Keith Theo G. Keith ◽  
Efstratios Nikolaidis
Keyword(s):  
Cavitation Bubble ◽  
Bubble Radius ◽  
Random Variable ◽  
Bubble Collapse ◽  
Maximum Pressure ◽  
Local Pressure ◽  
New Approach ◽  
Content Type ◽  
Collapse Pressure ◽  
Bubble Cavitation

PurposeThe purpose is to present a new approach for studying the phenomenon of traveling bubble cavitation.Design/methodology/approachA flow around a rigid, 2D hydrofoil (NACA‐0012) with a smooth surface is analyzed computationally. The Rayleigh‐Plesset equation is numerically integrated to simulate the growth and collapse of a cavitation bubble moving in a varying pressure field. The analysis is performed for both incompressible and compressible fluid cases. Considering the initial bubble radius as a uniformly distributed random variable, the probability density function of the maximum collapse pressure is determined.FindingsThe significance of the liquid compressibility during bubble collapse is illustrated. Furthermore, it is shown that the initial size of the bubble has a significant effect on the maximum pressure generated during the bubble collapse. The maximum local pressure developed during cavitation bubble collapse is of the order of 104 atm.Research limitations/implicationsA single bubble model that does not account for the effect of neighboring bubbles is used in this analysis. A spherical bubble is assumed.Originality/valueA new approach has been developed to simulate traveling bubble cavitation by interfacing a CFD solver for simulating a flow with a program simulating the growth and collapse of the bubble. Probabilistic analysis of the local pressure due to bubble collapse has been performed.

Numerical Investigation of Liquid Parameters Effect on the Oscillation of Cavitation Bubble

2014 ◽  
Vol 568-570 ◽  
pp. 1794-1800
Author(s):  
Xiu Mei Liu ◽  
Bei Bei Li ◽  
Wen Hua Li ◽  
Jie He ◽  
Jian Lu ◽  
...  
Keyword(s):  
Surface Tension ◽  
Cavitation Bubble ◽  
Bubble Dynamics ◽  
Dynamic Performance ◽  
Bubble Radius ◽  
Gas Content ◽  
Viscous Force ◽  
Bubble Collapse ◽  
Hydraulic Systems ◽  
Increasing Temperature

Cavitation is a common harmful phenomenon in hydraulic transmission systems. It not only damages flow continuity and reduces medium physical performance, but also induces vibration and noise. At the same time, the efficiency of a system is reduced due to cavitation, especially dynamic performance are deteriorated. Applying commercial CFD software FLUENT, the cavitation issuing from the orifice was numerically investigated, reducing the harm. The effect of liquid parameters (such as surface tension, gas content, and the temperature) on the oscillation of bubble is studied numerically. The modified Rayleigh-Plesset equations are presented to describe the oscillation of bubble in different liquids. Employing the finite difference calculus, the behavior of a cavitation bubble in liquids with different physics parameters are obtained. Meanwhile, the numerical results are compared with experiment results. It is observed that the viscous force decreases the growth and collapse of a bubble, making it expand or collapse less violently. And the surface-tension forces stave bubble growth progress and speed up bubble collapse process. On the other hand, both the maximum bubble radius and bubble lifetime increase with increasing temperature. These results can provide theory basis for understanding cavitation bubble dynamics in the hydraulic systems.

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