PIV Measurements of Cavitation Bubble Collapse Flow Induced by Pressure Wave

2010 ◽  
Author(s):  
Sheng-Hsueh Yang ◽  
Shenq-Yuh Jaw ◽  
Keh-Chia Yeh
Keyword(s):  
Cavitation Bubble ◽  
High Speed ◽  
Bubble Radius ◽  
Ccd Camera ◽  
Bubble Surface ◽  
Bubble Collapse ◽  
Solid Boundary ◽  
Liquid Jet ◽  
Pressure Waves ◽  
Critical Position

In this study, a single cavitation bubble is generated by rotating a U-tube filled with water. A series of bubble collapse flows induced by pressure waves of different strengths are investigated by positioning the cavitation bubble at different stand-off distances to a solid boundary. Particle images of bubble collapse flow recorded by high speed CCD camera are analyzed by multi-grid, iterative particle image distortion method. Detail velocity variations of the transient bubble collapse flow are obtained. It is found that a Kelvin–Helmholtz vortex is formed when a liquid jet penetrates the bubble surface. If the bubble center to the solid boundary is within one to three times of the bubble radius, the liquid jet is able to impinge the solid boundary to form a stagnation ring. The fluid inside the stagnation ring will be squeezed toward the center of the ring to form a counter jet. At certain critical position, the bubble collapse flow will produce a Kelvin–Helmholtz vortex, the Richtmyer-Meshkov instability, or the generation of a counter jet flow, depending on the strengths of the pressure waves. If the bubble surface is in contact with the solid boundary, the liquid jet can only splash inside-out without producing the stagnation ring and the counter jet. The complex phenomenon of cavitation bubble collapse flows is clearly manifested in this study.

Cinematographic Analysis of Counter Jet Formation in a Single Cavitation Bubble Collapse Flow

2011 ◽  
Vol 27 (2) ◽  
pp. 253-266 ◽  
Author(s):  
S.-H. Yang ◽  
S.-Y. Jaw ◽  
K.-C. Yeh
Keyword(s):  
Flow Field ◽  
Cavitation Bubble ◽  
Pressure Wave ◽  
Bubble Surface ◽  
Bubble Collapse ◽  
Solid Boundary ◽  
Liquid Jet ◽  
Pressure Waves ◽  
Field Variation ◽  
Critical Position

ABSTRACTThis study utilized a U-shape platform device to generate a single cavitation bubble for the detail analysis of the flow field characteristics and the cause of the counter jet during the process of bubble collapse induced by pressure wave. A series of bubble collapse flows induced by pressure waves of different strengths are investigated by positioning the cavitation bubble at different stand-off distances to the solid boundary. It is found that the Kelvin-Helmholtz vortices are formed when the liquid jet induced by the pressure wave penetrates the bubble surface. If the bubble center to the solid boundary is within one to three times the bubble's radius, a stagnation ring will form on the boundary when impacted by the penetrated jet. The liquid inside the stagnation ring is squeezed toward the center of the ring to form a counter jet after the bubble collapses. At the critical position, where the bubble center from the solid boundary is about three times the bubble's radius, the bubble collapse flows will vary. Depending on the strengths of the pressure waves applied, either just the Kelvin-Helmholtz vortices form around the penetrated jet or the penetrated jet impacts the boundary directly to generate the stagnation ring and the counter jet flow. This phenomenon used the particle image velocimetry method can be clearly revealed the flow field variation of the counter jet. If the bubble surface is in contact with the solid boundary, the liquid jet can only splash radially without producing the stagnation ring and the counter jet. The complex phenomenon of cavitation bubble collapse flows are clearly manifested in this study.

Experimental Study on Bubble Collapse Near a Solid Boundary

2016 ◽  
Author(s):  
Shuai Zhang ◽  
Shiping Wang ◽  
Yunlong Liu
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Bubble Radius ◽  
Water Layer ◽  
Lower Surface ◽  
Bubble Collapse ◽  
Solid Boundary ◽  
Liquid Jet ◽  
High Speed Photography ◽  
Generating Method

In this paper, we present a high-voltage electric-spark bubble-generating method which can generate a bubble with its maximum radius reaching up to ∼35 mm at a room pressure. Vertical migration and clear liquid jet inside the bubble are captured by a high speed photography. With this method, a series of experiments on bubbles collapse above a solid boundary are carried out under different non-dimensional standoff distances γ (= s/Rm, where s is the vertical distance from the bubble center to the solid boundary and Rm denotes the maximum bubble radius). It is found when bubble is extremely close to the solid boundary (γ < 0.6), the lower surface of the bubble will cling to the solid boundary, which causes the cone-shaped liquid jet to impact on solid boundary directly without buffering of the water layer. With the increase of γ, the bottom of the bubble is gradually away from the solid boundary with an increasing curvature, but the jet inside the bubble remains conical all along. The speed of the jet tip and the migration of the bubble top are also discussed subsequently, aiming to provide a reference for the numerical study. Finally, the critical value of γ is investigated, at which the effect of the buoyancy will compensate the attraction of the solid boundary when the buoyancy parameter of bubble is bout 0.06.

scholarly journals A Photographic Study of Spark-Induced Cavitation Bubble Collapse

1972 ◽  
Vol 94 (4) ◽  
pp. 825-832 ◽  
Author(s):  
C. L. Kling ◽  
F. G. Hammitt
Keyword(s):  
Cavitation Bubble ◽  
High Speed ◽  
Bubble Collapse ◽  
Solid Boundary ◽  
High Speed Photography ◽  
Minimum Volume ◽  
Cavitation Bubbles ◽  
Flowing System

The collapse of spark-induced cavitation bubbles in a flowing system was studied by means of high speed photography. The migration of cavitation bubbles toward a nearby solid boundary during collapse and rebound was observed. Near its minimum volume the bubble typically formed a high speed microjet, which struck the nearby surface causing individual damage craters on soft aluminum.

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 Bubble dynamics in a compressible liquid in contact with a rigid boundary

2015 ◽  
Vol 5 (5) ◽  
pp. 20150048 ◽  
Author(s):  
Qianxi Wang ◽  
Wenke Liu ◽  
A. M. Zhang ◽  
Yi Sui
Keyword(s):  
Shock Waves ◽  
Thin Layer ◽  
High Speed ◽  
Bubble Radius ◽  
Time History ◽  
Bubble Surface ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Imaging Method ◽  
Rigid Boundary

A bubble initiated near a rigid boundary may be almost in contact with the boundary because of its expansion and migration to the boundary, where a thin layer of water forms between the bubble and the boundary thereafter. This phenomenon is modelled using the weakly compressible theory coupled with the boundary integral method. The wall effects are modelled using the imaging method. The numerical instabilities caused by the near contact of the bubble surface with the boundary are handled by removing a thin layer of water between them and joining the bubble surface with its image to the boundary. Our computations correlate well with experiments for both the first and second cycles of oscillation. The time history of the energy of a bubble system follows a step function, reducing rapidly and significantly because of emission of shock waves at inception of a bubble and at the end of collapse but remaining approximately constant for the rest of the time. The bubble starts being in near contact with the boundary during the first cycle of oscillation when the dimensionless stand-off distance γ = s / R m < 1, where s is the distance of the initial bubble centre from the boundary and R m is the maximum bubble radius. This leads to (i) the direct impact of a high-speed liquid jet on the boundary once it penetrates through the bubble, (ii) the direct contact of the bubble at high temperature and high pressure with the boundary, and (iii) the direct impingement of shock waves on the boundary once emitted. These phenomena have clear potential to damage the boundary, which are believed to be part of the mechanisms of cavitation damage.

On the boundary integral method for the rebounding bubble

2007 ◽  
Vol 570 ◽  
pp. 407-429 ◽  
Author(s):  
M. LEE ◽  
E. KLASEBOER ◽  
B. C. KHOO
Keyword(s):  
Energy Loss ◽  
Integral Method ◽  
Bubble Radius ◽  
Experimental Studies ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Bubble Collapse ◽  
Solid Boundary ◽  
Bubble System ◽  
Toroidal Bubble

The formation of a toroidal bubble towards the end of the bubble collapse stage in the neighbourhood of a solid boundary has been successfully studied using the boundary integral method. The further evolution (rebound) of the toroidal bubble is considered with the loss of system energy taken into account. The energy loss is incorporated into a mathematical model by a discontinuous jump in the potential energy at the minimum volume during the short collapse–rebound period accompanying wave emission. This implementation is first tested with the spherically oscillating bubble system using the theoretical Rayleigh–Plesset equation. Excellent agreement with experimental data for the bubble radius evolution up to three oscillation periods is obtained. Secondly, the incorporation of energy loss is tested with the motion of an oscillating bubble system in the neighbourhood of a rigid boundary, in an axisymmetric geometry, using a boundary integral method. Example calculations are presented to demonstrate the possibility of capturing the peculiar entity of a counterjet, which has been reported only in recent experimental studies.

Dynamics of laser-induced cavitation bubbles near two perpendicular rigid walls

2018 ◽  
Vol 841 ◽  
pp. 28-49 ◽  
Author(s):  
Emil-Alexandru Brujan ◽  
Tatsuya Noda ◽  
Atsushi Ishigami ◽  
Toshiyuki Ogasawara ◽  
Hiroyuki Takahira
Keyword(s):  
High Speed ◽  
Vertical Wall ◽  
Bubble Surface ◽  
Bubble Collapse ◽  
High Speed Photography ◽  
Maximum Expansion ◽  
Toroidal Bubble ◽  
Horizontal Wall ◽  
The Moment ◽  
Rigid Walls

The behaviour of a laser-induced cavitation bubble near two perpendicular rigid walls and its dependence on the distance between bubble and walls is investigated experimentally. It was shown by means of high-speed photography with $100\,000~\text{frames}~\text{s}^{-1}$ that an inclined jet is formed during bubble collapse and the bubble migrates in the direction of the jet. At a given position of the bubble with respect to the horizontal wall, the inclination of the jet increases with decreasing distance between the bubble and the second, vertical wall. A bubble generated at equal distances from the walls develops a jet that is directed in their bisection. The penetration of the jet into the opposite bubble surface leads to the formation of an asymmetric toroidal bubble that is perpendicular to the jet direction. At a large distance from the rigid walls, the toroidal bubble collapses in the radial direction, eventually disintegrating into tiny microbubbles. When the bubble is in contact with the horizontal wall at its maximum expansion, the toroidal ring collapses in both radial and toroidal directions, starting from the bubble part opposite to the vertical wall, and the bubble achieves a crescent shape at the moment of second collapse. The bubble oscillation is accompanied by a strong migration along the horizontal wall.

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.

Cavitation Bubble Collapse Near a Heated Wall and Its Effect on the Heat Transfer

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Bin Liu ◽  
Jun Cai ◽  
Xiulan Huai ◽  
Fengchao Li
Keyword(s):  
Heat Transfer ◽  
Cavitation Bubble ◽  
Stokes Equations ◽  
Saturated Vapor ◽  
Bubble Diameter ◽  
Bubble Radius ◽  
Heated Wall ◽  
Bubble Collapse ◽  
Flow State ◽  
Vof Model

In the present work, a numerical investigation on the mechanism of heat transfer enhancement by a cavitation bubble collapsing near a heated wall has been presented. The Navier–Stokes equations and volume of fluid (VOF) model are employed to predict the flow state and capture the liquid-gas interface. The model was validated by comparing with the experimental data. The results show that the microjet violently impinges on the heated wall after the bubble collapses completely. In the meantime, the thickness of the thermal boundary layer and the wall temperature decrease significantly within the active scope of the microjet. The fresh low-temperature liquid and the impingement brought by the microjet should be responsible for the heat transfer reinforcement between the heated wall and the liquid. In addition, it is found that the impingement width of the microjet on the heated wall always keeps 20% of the bubble diameter. And, the enhancement degree of heat transfer significantly depends on such factors as stand-off distance, saturated vapor pressure, and initial bubble radius.

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