A Photographic Study of the Effect of an Air Bubble on the Growth and Collapse of a Vapor Bubble Near a Surface

1972 ◽  
Vol 94 (4) ◽  
pp. 933-940 ◽  
Author(s):  
R. H. Smith ◽  
R. B. Mesler
Keyword(s):  
Vapor Bubble ◽  
High Speed ◽  
Room Temperature ◽  
Solid Boundary ◽  
High Speed Photography ◽  
Air Bubbles ◽  
Gas Bubble ◽  
Air Bubble ◽  
Spark Gap ◽  
Damage Prevention

Interaction of an individual vapor bubble formed by a spark gap in water at room temperature with a neighboring air bubble, such as could have significance in cavitation, was investigated using high speed photography. Air bubbles were located both on and far from boundaries. An air bubble located on the solid boundary was able to protect the surface from damage. Two effects of the interaction which appeared to be important in the damage prevention were energy transfer from the vapor bubble to the gas bubble and repulsion of the vapor bubble by the gas bubble. Gas bubbles far from boundaries absorbed less energy and had less repulsive effect than those on solid boundaries.

Thermal Wake of a Single Rising Air Bubble in a Large Body of Stagnant Liquid

2007 ◽  
Author(s):  
Majid Molki ◽  
Bahman Abbasi
Keyword(s):  
High Speed ◽  
Thermal Field ◽  
Large Body ◽  
Heat Transfer Process ◽  
Computational Effort ◽  
Temperature Fields ◽  
High Speed Photography ◽  
Three Dimensional Model ◽  
Surrounding Water ◽  
Air Bubble

A computational effort was undertaken to study the thermal field behind a slowly rising solitary air bubble. Starting from rest, the bubble moves upward in water due to buoyancy force in the gravitational field and induces both internal and external motion. The bubble, being colder than the surrounding water, is heated by water. The upward motion deforms the shape of the bubble and generates a convective heat transfer process. Variation of temperature at the gas-liquid interface causes a local variation of surface tension. Although the problems of this type have been generally treated by the axisymmetric assumption, the present work employs a three-dimensional model that captures the azimuthal variation of flow parameters. High-speed photography was employed to visualize the bubble evolution from the onset until the bubble reached a certain velocity. The computations were performed using the finite-volume and Volume of Fluid (VOF) techniques. The shape and evolution of the bubble as predicted by the computations are compared with those captured on the high-speed photographs. The computations revealed details of the pressure and temperature fields inside and outside the bubble. They also indicated the thermal field in the wake region behind the bubble.

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.

Fluid Drag Force Production and Motion Control of an Aquarobot Manipulator by Ejecting Air Bubbles

1990 ◽  
Vol 2 (5) ◽  
pp. 351-357
Author(s):  
Masakazu Ogasawara ◽  
◽  
Fumio Hara ◽  
Keyword(s):  
Drag Force ◽  
High Speed ◽  
Robot Manipulator ◽  
Force Production ◽  
Air Bubbles ◽  
Air Bubble ◽  
Fluid Forces ◽  
Fluid Drag ◽  
Force Reduction ◽  
Controlled Flow

The motion of a robot manipulator submerged in water is strongly affected by fluid forces, and it is an important technique to avoid their influence on the motion of an aquarobot manipulator to achieve high-speed, precise motion. This paper deals with extension of the technique of air bubble ejection from the manipulator surface, i.e., the mechanisms of reduction of drag force by air bubble ejection and its effects on the control of the aquarobot manipulator. Using a two-degree-of-freedom and two-joint manipulator, experiments were performed and the following major results were obtained: (1) There exists a particular pattern of air bubble ejection for reduction fluid drag force acting on the manipulator and it resulted in reduction of drag force by 25% compared to that for no air bubble ejection. (2) There exists a particular pattern of air bubble ejection that brought a 40% reduction of the control torque required for compensating the fluid drag force. (3) The major mechanisms for drag force reduction were found to be the controlled flow pattern around the manipulator formed by ejecting air bubbles. However, it is noted that these effects of air bubble ejection were dependent on the mode of manipulator motion.

INVESTIGATION OF THE CAVITATION AND PRESSURE CHANGE OF BRAIN TISSUE BASED ON A TRANSPARENT HEAD MODEL IN ITS DECELERATING IMPACT

2010 ◽  
Vol 10 (02) ◽  
pp. 361-372 ◽  
Author(s):  
SHENGXIONG LIU ◽  
ZHIYONG YIN ◽  
HUI ZHAO ◽  
GUANGYU YANG
Keyword(s):  
Brain Tissue ◽  
Normal Level ◽  
High Speed ◽  
Pressure Change ◽  
Positive Pressure ◽  
Head Model ◽  
Air Bubbles ◽  
Half Cycle ◽  
Air Bubble ◽  
The Brain

In this paper, a transparent physical head model with air bubbles to simulate the brain cavitation phenomena in head decelerating impact is presented. The transparent skull model was generated based on a real human skull through the turnover formwork technique, and a transparent gel was used to substitute the brain tissue. Air bubbles were created in the gel at the representative sites such as coup site and contrecoup site. After this, the head model was made to free fall from a position and impact on a fixed platform. The decelerating impacting process was recorded by a high-speed video camera and an accelerometer system. Through analyzing the video, the volume change of the air bubbles, namely, the mean pressure change of the air bubbles were calculated and compared. This new method has an advantage in investigating the brain cavitation phenomena using a direct and visual technique. The results showed explicitly and effectively that during the decelerating impact the contrecoup site air bubble was exposed mainly to a negative pressure which value became smaller and smaller in the first half of the impacting cycle and then came near to the normal level in the second half of the cycle; contrarily, the coup site air bubble was exposed mainly to a positive pressure which value became greater and greater in the first half of the impacting cycle and then came near to the normal level in the second half cycle. The probable biomechanics of the cavitation phenomenon is also given in this paper.

An Experimental Study of Accelerated Cavitation Induced by Ultrasonics

1965 ◽  
Vol 87 (4) ◽  
pp. 967-976 ◽  
Author(s):  
F. Numachi
Keyword(s):  
Experimental Study ◽  
Frequency Spectrum ◽  
High Speed ◽  
Present Report ◽  
Ultrasonic Waves ◽  
High Speed Photography ◽  
Air Bubbles ◽  
The Waves

With a view to clarifying cavitation phenomena induced by ultrasonic waves, utilized recently in erosion tests, the frequency spectrum of the waves caused by cavitation was obtained, and the pattern of air bubbles produced were observed by high-speed photography. Some considerations also are given in the present report on the amount and form of erosion caused by cavitation.

MULTIPLE SPARK-GENERATED BUBBLE INTERACTIONS

2009 ◽  
Vol 23 (03) ◽  
pp. 229-232 ◽  
Author(s):  
BOO CHEONG KHOO ◽  
DEEPAK ADIKHARI ◽  
SIEW WAN FONG ◽  
EVERT KLASEBOER
Keyword(s):  
High Speed ◽  
Bubble Surface ◽  
Solid Boundary ◽  
High Speed Photography ◽  
Bubble Interactions ◽  
Complex Interactions ◽  
Bubble Splitting ◽  
Shape Changes ◽  
Insight Into ◽  
Phase Differences

The complex interactions of two and three spark-generated bubbles are studied using high speed photography. The corresponding simulations are performed using a 3D Boundary Element Method (BEM) code. The bubbles generated are between 3 to 5 mm in radius, and they are either in-phase or out-of-phase with one another. The possible interaction phenomena between two identically sized bubbles are summarized. Depending on their relative distances and phase differences, they can coalesce, jet towards or away from one another, split into smaller bubbles, or 'catapult' away from one another. The 'catapult' effect can be utilized to generated high speed jet in the absence of a solid boundary or shockwave. Also three bubble interactions are highlighted. Complicated phenomena such as bubble forming an elliptical shape and bubble splitting are observed. The BEM simulations provide insight into the physics of the phenomena by providing details such as detailed bubble shape changes (experimental observations are limited by the temporal and spatial resolution), and jet velocity. It is noted that the well-tested BEM code [1,2] utilized here is computationally very efficient as compared to other full-domain methods since only the bubble surface is meshed.

Numerical and Experimental Studies of Collapsing Cavitation Bubbles for Ballast Water Treatment

2018 ◽  
Author(s):  
Chang-Wei Kang ◽  
Tandiono Tandiono ◽  
Xin Lu ◽  
Cary K. Turangan ◽  
Hafiiz Osman ◽  
...  
Keyword(s):  
High Speed ◽  
Experimental Studies ◽  
Hydrodynamic Cavitation ◽  
High Speed Photography ◽  
Gas Bubble ◽  
Liquid Pressure ◽  
Cfd Simulations ◽  
Bubble Cloud ◽  
Computational Fluid Dynamics Cfd ◽  
Sudden Jump

In this paper, we report both experimental and computational studies of hydrodynamic cavitation generated by accelerating liquid through a series of constrictions. The detailed process of cavitation generation is visualized using a high-speed photography. The cavitation is initiated when a gas bubble moves towards the constrictions. The gas bubble initially accelerates, expands and then splits into smaller bubbles when it moves along the constriction. As these bubbles migrate into a large liquid compartment, they collapse violently to form a bubble cloud, owing to a sudden jump in liquid pressure in the compartment. The experimental observation is further confirmed using computational fluid dynamics (CFD) simulations. We also present experimental evidence showing a significant reduction in gram-negative Escherichia coli concentration after it passes through the constrictions.

Observations of radiations forces effects on individual air bubbles with high speed photography

2004 ◽  
Author(s):  
P. Palanchon ◽  
P. Tortoli ◽  
M. Corsi ◽  
A. Bouakaz ◽  
M. Versluis ◽  
...  
Keyword(s):  
High Speed ◽  
High Speed Photography ◽  
Air Bubbles

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.

Design of High-Speed Photography Optical System for Air Bubbles in Water

2012 ◽  
Vol 32 (4) ◽  
pp. 0422002
Author(s):  
谢正茂 Xie Zhengmao ◽  
高立民 Gao Limin ◽  
何俊华 He Junhua
Keyword(s):  
Optical System ◽  
High Speed ◽  
High Speed Photography ◽  
Air Bubbles
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