scholarly journals High-speed photography of shock waves with an adaptive illumination

2020 ◽  
Vol 45 (6) ◽  
pp. 1547 ◽  
Author(s):  
Vid Agrež ◽  
Tomaž Požar ◽  
Rok Petkovšek
Keyword(s):  
Shock Waves ◽  
High Speed ◽  
High Speed Photography

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.

Detonation Behaviors of Nitromethane with Various Initiating Shock Pressure

2007 ◽  
Vol 566 ◽  
pp. 41-46 ◽  
Author(s):  
Hideki Hamashima ◽  
Akinori Osada ◽  
Shigeru Itoh ◽  
Yukio Kato
Keyword(s):  
Shock Waves ◽  
High Speed ◽  
Shock Pressure ◽  
High Speed Photography ◽  
Detailed Structure ◽  
Complicated Structure ◽  
Low Velocity ◽  
Cavitation Field ◽  
Liquid Explosives ◽  
Multiple Shock

Some liquid explosives have two different detonation behaviors: high velocity detonation (HVD) or low velocity detonation (LVD). The detonation behavior depends on the level of the initiating shock pressure. The detailed structure of LVD in liquid explosives has not yet been clarified. A physical model was proposed that LVD is not a self-reactive detonation, but rather a supported-reactive detonation from the cavitation field generated by precursor shock waves. In this study, high-speed photography was used to investigate the detonation behavior of nitromethane (NM) with the various initiating shock pressures. Stable LVD was not observed, only transient LVD was observed. A very complicated structure of LVD was observed: the interaction of multiple precursor shock waves, multiple oblique shock waves, and a cavitation field. Multiple shock waves propagating in non-detonating NM were observed for shock pressures below the range required for LVD, while above the LVD range HVD was observed.

scholarly journals Experimental Study of Kerosene Ignition and Flame Stabilization in a Supersonic Combustor

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Yu Meng ◽  
Hongbin Gu ◽  
Xinyu Zhang
Keyword(s):  
Shock Waves ◽  
Combustion Chamber ◽  
High Speed ◽  
Flame Stabilization ◽  
Supersonic Combustion ◽  
Chamber Pressure ◽  
High Speed Photography ◽  
Flame Stability ◽  
Whole Process ◽  
Stable Flame

Abstract A supersonic kerosene ignition and flame stabilization experiments were conducted on a directly connected supersonic combustion test bench. The kerosene fuel was jetted by wall jet at Ma 2.5 airflow. High-speed photography was used to record the CH* emission during ignition, extinguishing and evolution of the flame. Experiments of different equivalence ratios were performed. The processes of ignition, flame holding, and extinguishing were observed as well. The experiment showed the characteristics of ignition core initiation and extension. The time of ignition increased with the increase of equivalence ratios. Flame stability during the process of Ma 2.5 at the entrance of the combustion chamber was also studied. An equilibrium flame pattern of shock wave and flame was discovered in the experiment. In the stable flame state, shock waves near the kerosene jet orifice promote atomization and blending, and the combustion chamber pressure with stable flame makes the shock waves stable near the kerosene jet orifice, thus forming the flame stability model. The whole process and characteristics of kerosene ignition, flame holding and extinguishing are revealed in the experiment.

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.

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