Cavitation erosion of aluminum considering bubble collapse, pulse height spectra and cavitation erosion efficiency

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.

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Cavitation erosion behavior of hydraulic concrete under high-speed flow

Anti-Corrosion Methods and Materials ◽

10.1108/acmm-03-2021-2459 ◽

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.

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Comparison of multiphase models for computing shock-induced bubble collapse

International Journal of Numerical Methods for Heat &amp Fluid Flow ◽

10.1108/hff-05-2019-0399 ◽

2019 ◽

Vol 30 (8) ◽

pp. 3845-3877 ◽

Cited By ~ 1

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.

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Study of Quantitative Numerical Prediction of Cavitation Erosion in Cavitating Flow

Journal of Fluids Engineering ◽

10.1115/1.4023072 ◽

2012 ◽

Vol 135 (1) ◽

Cited By ~ 12

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.

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Role of Bubble Collapse Pressure in Cavitation Erosion.

JSME International Journal Series A ◽

10.1299/jsmea.41.96 ◽

1998 ◽

Vol 41 (1) ◽

pp. 96-102 ◽

Cited By ~ 3

Author(s):

Hiroyuki MORI ◽

Shuji HATTORI ◽

Tsunenori OKADA

Keyword(s):

Cavitation Erosion ◽

Bubble Collapse ◽

Collapse Pressure

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Quantitative Evaluation of Cavitation Erosion

Journal of Fluids Engineering ◽

10.1115/1.2819644 ◽

1998 ◽

Vol 120 (1) ◽

pp. 179-185 ◽

Cited By ~ 39

Author(s):

Shuji Hattori ◽

Hiroyuki Mori ◽

Tsunenori Okada

Keyword(s):

Impact Energy ◽

Cavitation Erosion ◽

Erosion Resistance ◽

Impact Load ◽

Bubble Collapse ◽

Impact Loads ◽

Volume Loss ◽

Developed Pressure ◽

Cavitation Erosion Resistance ◽

The Impact

In order to evaluate the quantitative cavitation-erosion resistance of materials, a pressure-detector-installed specimen was developed, which can measure both the impact load produced by cavitation bubble collapse and the volume loss simultaneously. Test specimens (pressure-detection rod) used were nine kinds of metals and were exposed to vibratory cavitation. A linear relation was obtained for all materials between the accumulated impact energy ∑Fi2 calculated from the distribution of impact loads and the volume loss, independent of test conditions. Impact energy accumulated during the incubation period and the energy for a unit material removal in steady-state period were obtained from the relation. These values are very Important concerning quantitative erosion resistance evaluation. That is, when the distribution of impact loads is acquired for different cavitation conditions, the volume loss can be estimated. This idea was applied to the venturi cavitation erosion. The experimental results for venturi test corresponds well with the prediction using these impact energy values. It was concluded that the quantitative impact energy values of materials can be determined independent of the apparatus and the test condition by using the newly developed pressure-detector-installed specimen.

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