scholarly journals Role of Bubble Collapse Pressure in Cavitation Erosion.

1998 ◽  
Vol 41 (1) ◽  
pp. 96-102 ◽  
Author(s):  
Hiroyuki MORI ◽  
Shuji HATTORI ◽  
Tsunenori OKADA
Keyword(s):  
Cavitation Erosion ◽  
Bubble Collapse ◽  
Collapse Pressure

Influence of Cathodic and Anodic Currents on Cavitation Erosion

CORROSION ◽  
1993 ◽  
Vol 49 (11) ◽  
pp. 910-920 ◽  
Author(s):  
J. G. Auret ◽  
O. F. R. A. Damm ◽  
G. J. Wright ◽  
F. P. A. Robinson
Keyword(s):  
Corrosion Rate ◽  
Cavitation Erosion ◽  
Loss Rate ◽  
Mechanical Damage ◽  
Bubble Collapse ◽  
Volume Loss ◽  
Test Rig ◽  
Anodic Current ◽  
Cathodic Current ◽  
Geometrical Effects

Abstract A vibratory-type cavitation test rig was constructed to study the effect of polarizing currents applied to a cavitating body. The generation of gas by electrolysis reduced mechanical damage suffered by a cavitating body because of bubble collapse cushioning. However, the net effect on overall damage depended on several factors, including the intensity of mechanical attack, corrosion rate, and surface geometrical effects. A cathodic current was shown to always decrease of the total volume loss rate, but the volume loss rate sometimes was increased and sometimes was reduced in the anodic current range.

Cavitation erosion behavior of hydraulic concrete under high-speed flow

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xin Wang ◽  
Ting-Qiang Xie
Keyword(s):  
Cavitation Bubble ◽  
High Speed ◽  
Cavitation Erosion ◽  
Concrete Strength ◽  
Bubble Collapse ◽  
High Speed Flow ◽  
Content Type ◽  
Erosion Behavior ◽  
Hydraulic Concrete ◽  
Speed Flow

Purpose Cavitation erosion has always been a common technical problem in a hydraulic discharging structure. This paper aims to investigate the cavitation erosion behavior of hydraulic concrete under high-speed flow. Design/methodology/approach A high-speed and high-pressure venturi cavitation erosion generator was used to simulate the strong cavitation. The characteristics of hydrodynamic loads of cavitation bubble collapse zone, the failure characteristics and the erosion development process of concrete were investigated. The main influencing factors of cavitation erosion were discussed. Findings The collapse of the cavitation bubble group produced a high frequency, continuous and unsteady pulse load on the wall of concrete, which was more likely to cause fatigue failure of concrete materials. The cavitation action position and the main frequency of impact load were greatly affected by the downstream pressure. A power exponential relationship between cavitation load, cavitation erosion and flow speed was observed. With the increase of concrete strength, the degree of damage of cavitation erosion was approximately linearly reduced. Originality/value After cavitation erosion, a skeleton structure was formed by the accumulation of granular particles, and the relatively independent bulk structure of the surface differed from the flake structure formed after abrasion.

scholarly journals Comparison of multiphase models for computing shock-induced bubble collapse

2019 ◽  
Vol 30 (8) ◽  
pp. 3845-3877 ◽  
Author(s):  
Eric Goncalves Da Silva ◽  
Philippe Parnaudeau
Keyword(s):  
Blast Wave ◽  
Cavitation Erosion ◽  
Volume Fraction ◽  
Free Field ◽  
Three Dimensional ◽  
Strong Shock ◽  
Bubble Collapse ◽  
Multiphase Model ◽  
Content Type ◽  
Multiphase Models

Purpose The purpose of this paper is to quantify the relative importance of the multiphase model for the simulation of a gas bubble impacted by a normal shock wave in water. Both the free-field case and the collapse near a wall are investigated. Simulations are performed on both two- and three-dimensional configurations. The main phenomena involved in the bubble collapse are illustrated. A focus on the maximum pressure reached during the collapse is proposed. Design/methodology/approach Simulations are performed using an inviscid compressible homogeneous solver based on different systems of equations. It consists in solving different mixture or phasic conservation laws and a transport-equation for the gas volume fraction. Three-dimensional configurations are considered for which an efficient massively parallel strategy was developed. The code is based on a finite volume discretization for which numerical fluxes are computed with a Harten, Lax, Van Leer, Contact (HLLC) scheme. Findings The comparison of three multiphase models is proposed. It is shown that a simple four-equation model is well-suited to simulate such strong shock-bubble interaction. The three-dimensional collapse near a wall is investigated. It is shown that the intensity of pressure peaks on the wall is drastically increased (more than 200 per cent) in comparison with the cylindrical case. Research limitations/implications The study of bubble collapse is a key point to understand the physical mechanism involved in cavitation erosion. The bubble collapse close to the wall has been addressed as the fundamental mechanism producing damage. Its general behavior is characterized by the formation of a water jet that penetrates through the bubble and the generation of a blast wave during the induced collapse. Both the jet and the blast wave are possible damaging mechanisms. However, the high-speed dynamics, the small spatio-temporal scales and the complicated physics involved in these processes make any theoretical and experimental approach a challenge. Practical implications Cavitation erosion is a major problem for hydraulic and marine applications. It is a limiting point for the conception and design of such components. Originality/value Such a comparison of multiphase models in the case of a strong shock-induced bubble collapse is clearly original. Usually models are tested separately leading to a large dispersion of results. Moreover, simulations of a three-dimensional bubble collapse are scarce in the literature using such fine grids.

Study of Quantitative Numerical Prediction of Cavitation Erosion in Cavitating Flow

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Naoya Ochiai ◽  
Yuka Iga ◽  
Motohiko Nohmi ◽  
Toshiaki Ikohagi
Keyword(s):  
Erosion Rate ◽  
Cavitation Erosion ◽  
Prediction Method ◽  
Cavitating Flow ◽  
Quantitative Prediction ◽  
Bubble Collapse ◽  
Coupled Analysis ◽  
Material Surface ◽  
Two Phase ◽  
Navier Stokes Equation

Cavitation erosion is a material damage phenomenon caused by the repeated application of impulsive pressure on a material surface induced by bubble collapse, and the establishment of a method by which to numerically predict cavitation erosion is desired. In the present study, a numerical quantitative prediction method of cavitation erosion in a cavitating flow is proposed. In the present method, a one-way coupled analysis of a cavitating flow field based on a gas-liquid two-phase Navier–Stokes equation (Eulerian) and bubbles in the cavitating flow by bubble dynamics (Lagrangian) is used to treat temporally and spatially different scale phenomena, such as the macroscopic phenomenon of a cavitating flow and the microscopic phenomenon of bubble collapse. Impulsive pressures acting on a material surface are evaluated based on the bubble collapse position, time, and intensity, and the erosion rate is quantitatively predicted using an existing material-dependent relationship between the impulsive energy (square of the impulsive force) and the maximum erosion rate. The erosion rate on a NACA0015 hydrofoil surface in an unsteady transient cavitating flow is predicted by the proposed method. The distribution of the predicted erosion rate corresponds qualitatively to the distribution of an experimental surface roughness increment of the same hydrofoil. Furthermore, the predicted erosion rate considering the bubble nuclei distribution is found to be of the same order of magnitude as the actual erosion rate, which indicates that considering bubble nuclei distribution is important for the prediction of cavitation erosion and that the present prediction method is valid to some degree.

scholarly journals The transition from sheet to cloud cavitation

2017 ◽  
Vol 817 ◽  
pp. 439-454 ◽  
Author(s):  
P. F. Pelz ◽  
T. Keil ◽  
T. F. Groß
Keyword(s):  
Reynolds Number ◽  
Cavitation Number ◽  
Wall Friction ◽  
Bubble Collapse ◽  
Penetration Length ◽  
Cloud Cavitation ◽  
Viscous Film ◽  
History Of ◽  
Good Agreement

Recent studies indicate that the transition from sheet to cloud cavitation depends on both cavitation number and Reynolds number. In the present paper this transition is investigated analytically and a physical model is introduced. In order to include the entire process, the model consists of two parts, a model for the growth of the sheet cavity and a viscous film flow model for the so-called re-entrant jet. The models allow the calculation of the length of the sheet cavity for given nucleation rates and initial nuclei radii and the spreading history of the viscous film. By definition, the transition occurs when the re-entrant jet reaches the point of origin of the sheet cavity, implying that the cavity length and the penetration length of the re-entrant jet are equal. Following this criterion, a stability map is derived showing that the transition depends on a critical Reynolds number which is a function of cavitation number and relative surface roughness. A good agreement was found between the model-based calculations and the experimental measurements. In conclusion, the presented research shows the evidence of nucleation and bubble collapse for the growth of the sheet cavity and underlines the role of wall friction for the evolution of the re-entrant jet.

Propagation of Bubble Collapse Pressure Generating at Cavitation Break-down

2004 ◽  
Vol 2004.2 (0) ◽  
pp. 449-450
Author(s):  
Hirotaka DAN ◽  
Ryousuke ADACHI ◽  
Kazuhiko KATO ◽  
Yasuaki MATUDAIRA
Keyword(s):  
Bubble Collapse ◽  
Collapse Pressure

Stability and Collapsing Mechanism of Cavitation-Induced Nanobubbles in Simulated Extra-Cellular Matrix (ECM) Near Neuron

2016 ◽  
Author(s):  
Y.-T. Wu ◽  
A. Adnan
Keyword(s):  
Extra Cellular Matrix ◽  
Bubble Collapse ◽  
Experimental Investigations ◽  
Perineuronal Nets ◽  
Neuron Damage ◽  
The Stability ◽  
The Relationship ◽  
Fluid Interaction ◽  
Cellular Matrix

In blast-induced traumatic brain injury, shock waves (SW) play an important role along with cavitation phenomena. Due to the lack of reliable and reproducible experimental investigations, we have a limited understanding of the role of cavitation in brain damage. The present study aims to develop an atomistic simulation model to determine the role of shock-induced impulse and different constituents of the brain’s extra-cellular matrix (ECM) on the formation mechanism, stability and collapsing mechanism of nanobubbles in the ECM. The ECM in the brain can be divided into three major types depending on their location behind the blood-brain barrier, namely (a) the basement membrane (basal lamina), (b) the perineuronal nets and (3) the neural interstitial matrix. In this paper, we have studied the interaction of nanobubbles with bio-molecules of the perineuronal nets. We have chosen this zone of the ECM because we are interested to obtain the role of cavitation bubble collapse in neuron damage. Most biomolecules of perineuronal nets are slender in shape and flexible which is believed to induce special solid-fluid interaction between the fluid domain and the solid domain within the ECM. In addition, perineuronal nets contain a significant number of sodium ions. The relationship between sodium ion and solid-like constituents of perineuronal nets on the stability and the collapsing mechanism of nanobubbles will be discussed.

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.

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