A study of the collapse of arrays of cavities

1988 ◽  
Vol 190 ◽  
pp. 409-425 ◽  
Author(s):  
J. P. Dear ◽  
J. E. Field
Keyword(s):  
Shock Wave ◽  
High Speed ◽  
High Speed Photography ◽  
Cavitation Damage ◽  
Major Mechanism ◽  
Collapse Mechanisms ◽  
Multiple Jets ◽  
Circular Holes ◽  
Schlieren Photography ◽  
Thick Glass

This paper describes a method for examining the collapse of arrays of cavities using high-speed photography and the results show a variety of different collapse mechanisms. A two-dimensional impact geometry is used to enable processes occurring inside the cavities such as jet motion, as well as the movement of the liquid around the cavities, to be observed. The cavity arrangements are produced by first casting water/gelatine sheets and then forming circular holes, or other desired shapes, in the gelatine layer. The gelatine layer is placed between two thick glass blocks and the array of cavities is then collapsed by a shock wave, visualized using schlieren photography and produced from an impacting projectile. A major advantage of the technique is that cavity size, shape, spacing and number can be accurately controlled. Furthermore, the shape of the shock wave and also its orientation relative to the cavities can be varied. The results are compared with proposed interaction mechanisms for the collapse of pairs of cavities, rows of cavities and clusters of cavities. Shocks of kbar (0.1 GPa) strength produced jets of c. 400 m s−1 velocity in millimetre-sized cavities. In closely-spaced cavities multiple jets were observed. With cavity clusters, the collapse proceeded step by step with pressure waves from one collapsed row then collapsing the next row of cavities. With some geometries this leads to pressure amplification. Jet production by the shock collapse of cavities is suggested as a major mechanism for cavitation damage.

Crack divergence phenomena in tempered glass

2020 ◽  
Vol 13 (3) ◽  
pp. 115-129
Author(s):  
Shin’ichi Aratani
Keyword(s):  
Optimal Design ◽  
High Speed ◽  
Glass Plate ◽  
Acute Angle ◽  
Divergence Angle ◽  
High Speed Photography ◽  
Tempered Glass ◽  
Thick Glass

High speed photography using the Cranz-Schardin camera was performed to study the crack divergence and divergence angle in thermally tempered glass. A tempered 3.5 mm thick glass plate was used as a specimen. It was shown that two types of bifurcation and branching existed as the crack divergence. The divergence angle was smaller than the value calculated from the principle of optimal design and showed an acute angle.

Flow Characteristics of Rectangular Liquid Jets Injected Into Low Subsonic Crossflow

2019 ◽  
Author(s):  
M. Tadjfar ◽  
A. Jaberi ◽  
R. Shokri
Keyword(s):  
High Speed ◽  
Flow Characteristics ◽  
Combustion Efficiency ◽  
Liquid Jets ◽  
High Speed Photography ◽  
Aspect Ratios ◽  
Jet Trajectory ◽  
Wide Range ◽  
Circular Holes ◽  
Subsonic Crossflow

Abstract Perpendicular injection of liquid jets into gaseous crossflow is well-known as an effective way to obtain good mixing between liquid fuel and air crossflow. Mostly, injectors with circular holes were used as the standard method of fuel spraying. However, recently a great attention to injectors with non-circular holes has emerged that aims to improve the quality of fuel mixing and consequently combustion efficiency. In the present work, rectangular injectors with different aspect ratios varying from 1 to 4 were experimentally studied. Using a wind tunnel with maximum air velocity of 42 m/s, tests were performed for a wide range of flow conditions including liquid-to-air momentum ratios of 10, 20, 30 and 40. Backlight shadowgraphy and high speed photography were employed to capture the instantaneous physics of the liquid jets discharged into gaseous crossflow. The flow physics of the rectangular liquid jets were investigated by means of flow visualizations. Different regimes of flow breakup including capillary, arcade, bag and multimode were observed for rectangular jets. Moreover, a new technique was used to calculate the trajectory of the liquid jets. It was shown the nozzle’s shape has no significant effect on jet trajectory. Also, the momentum ratio was found to has a profound effect on jet trajectory.

scholarly journals STUDY OF STEEL BARRIER SURFACE AFTER HIGH-SPEED EXPOSURE OF W AND TIC POWDERS

2021 ◽  
pp. 23-27
Author(s):  
E. V. Petrov ◽  
V. S. Trofimov ◽  
V. O. Kopytskiy
Keyword(s):  
Mechanical Properties ◽  
Shock Wave ◽  
High Speed ◽  
Physical And Mechanical Properties ◽  
High Speed Photography ◽  
Shock Wave Loading ◽  
Wave Loading ◽  
Barrier Material ◽  
Barrier Surface ◽  
Powder Particles

The surface layer of an obstacle made of U8 steel is investigated after high-speed exposure to a flow of powder particles. After analyzing the frames of high-speed photography, the average velocities of movement of particles of tungsten and titanium carbide powders were determined. It is shown that the shock-wave loading of the barrier material and the effect of particles accelerated by the explosion energy provide a change in the physical and mechanical properties of the surface and the volume of the steel barrier material.

Investigation of a converging underwater shock wave using high-speed photography

1995 ◽  
Author(s):  
Shigeru Itoh ◽  
S. Kubota ◽  
Shirou Nagano ◽  
I. Morita ◽  
A. Chiba ◽  
...  
Keyword(s):  
Shock Wave ◽  
High Speed ◽  
High Speed Photography ◽  
Underwater Shock Wave ◽  
Underwater Shock

scholarly journals Bubbles with shock waves and ultrasound: a review

2015 ◽  
Vol 5 (5) ◽  
pp. 20150019 ◽  
Author(s):  
Siew-Wan Ohl ◽  
Evert Klaseboer ◽  
Boo Cheong Khoo
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Biomedical Applications ◽  
High Speed ◽  
Experimental Studies ◽  
High Intensity Focused Ultrasound ◽  
High Speed Photography ◽  
Sound Waves ◽  
Bubble Cloud ◽  
Bubble Interaction

The study of the interaction of bubbles with shock waves and ultrasound is sometimes termed ‘acoustic cavitation'. It is of importance in many biomedical applications where sound waves are applied. The use of shock waves and ultrasound in medical treatments is appealing because of their non-invasiveness. In this review, we present a variety of acoustics–bubble interactions, with a focus on shock wave–bubble interaction and bubble cloud phenomena. The dynamics of a single spherically oscillating bubble is rather well understood. However, when there is a nearby surface, the bubble often collapses non-spherically with a high-speed jet. The direction of the jet depends on the ‘resistance' of the boundary: the bubble jets towards a rigid boundary, splits up near an elastic boundary, and jets away from a free surface. The presence of a shock wave complicates the bubble dynamics further. We shall discuss both experimental studies using high-speed photography and numerical simulations involving shock wave–bubble interaction. In biomedical applications, instead of a single bubble, often clouds of bubbles appear (consisting of many individual bubbles). The dynamics of such a bubble cloud is even more complex. We shall show some of the phenomena observed in a high-intensity focused ultrasound (HIFU) field. The nonlinear nature of the sound field and the complex inter-bubble interaction in a cloud present challenges to a comprehensive understanding of the physics of the bubble cloud in HIFU. We conclude the article with some comments on the challenges ahead.

New crack generation phenomena by crack collision in 10 mm thick tempered glass

2021 ◽  
pp. 1-13
Author(s):  
Shin’ichi Aratani
Keyword(s):  
Tensile Stress ◽  
Crack Propagation ◽  
High Speed ◽  
Crack Tip ◽  
High Speed Photography ◽  
Tempered Glass ◽  
Crack Generation ◽  
Caustics Method ◽  
Thick Glass ◽  
Collision Angle

High speed photography by Caustics method using Cranz–Schardin camera was used to study crack propagation and divergence in thermally tempered glass. Tempered 10 mm thick glass plates were used as a specimen. New crack generation by two crack collision was observed. Regarding the presence/absence of new cracks, the dependence of the two cracks on the collision angle was confirmed. Considering that it is based on the synthesis of stress 𝜎CR generated at the crack tip, tensile stress necessary for the generation of new cracks could be created.

Crack propagation and divergence phenomena observed by Caustics method in tempered glass

2021 ◽  
pp. 1-18
Author(s):  
Shin’ichi Aratani
Keyword(s):  
Crack Propagation ◽  
High Speed ◽  
High Speed Photography ◽  
Tempered Glass ◽  
Glass Plates ◽  
The Difference ◽  
Caustics Method ◽  
Thick Glass

High speed photography by Caustics method using Cranz-Schardin camera was studied for crack propagation and divergence in thermally tempered glass. Tempered 10 mm thick glass plates were used as a specimen. Two types of bifurcation and branching as the crack divergence could be observed and clarified even in 10 mm thick tempered glass. The difference of the shadow spot sizes between bifurcation type and branching type could be confirmed.

High Speed Photography For Studying The Shock Wave Propagation At High Mach Numbers Through A Reflection Nozzle

1979 ◽  
Author(s):  
S. G. Zaytsev ◽  
E. V. Lazareva ◽  
A. V. Mikhailova ◽  
V. L. Nikolaev-Kozlov ◽  
E. I. Chebotareva
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
High Speed ◽  
Shock Wave Propagation ◽  
High Speed Photography ◽  
Mach Numbers ◽  
High Mach

DETERMINATION SOUND SPEED OF METAL IN AQUEOUS SOLUTION VIA LASER INDUCED ACOUSTIC WAVE TECHNIQUE

2016 ◽  
Vol 78 (3) ◽  
Author(s):  
Maisarah Duralim ◽  
Noriah Bidin ◽  
Waskito Nugroho ◽  
Jasman Zainal
Keyword(s):  
Shock Wave ◽  
Aqueous Solution ◽  
Acoustic Wave ◽  
Sound Speed ◽  
High Speed ◽  
Optical Breakdown ◽  
High Speed Photography ◽  
Nonlinear Phenomena ◽  
Metal Element ◽  
Laser Induced Breakdown

Laser induced breakdown and shock wave propagation are nonlinear phenomena. The high temperature and high pressure associated with plasma formation offering a lot advantages in industrial and scientific research.  However not many realized that the end  product of nonlinear effect such as the generation of acoustic wave will also attribute to significant impact. Thus the intention of this study is to materialize the usefulness of such acoustic wave for determination the sound speed of metal element like Pb, Hg and K in aqueous solution. In this attempt a Q-switched Nd:YAG laser was focused to induce optical breakdown and its associated shock wave generation which later  follow by the generation of acoustic wave. The phenomenon is observed in conjunction with high speed photography based shadowgraph technique. The experimental results of sound speed for K, Hg and Pb is found in good agreement with the standard value from references. This confirmed that laser induced acoustic wave will be other alternative method for measuring sound speed for metal element in periodic table.

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