HIGH-SPEED PHOTOGRAPHY OF DETONATION PROPAGATION IN DYNAMICALLY PRECOMPRESSED LIQUID EXPLOSIVES

2008 ◽  
Author(s):  
O. E. Petel ◽  
A. J. Higgins ◽  
A. C. Yoshinaka ◽  
F. Zhang ◽  
Mark Elert ◽  
...  
Keyword(s):  
High Speed ◽  
High Speed Photography ◽  
Detonation Propagation ◽  
Liquid Explosives

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.

The role of cavities in the initiation and growth of explosion in liquids

1973 ◽  
Vol 335 (1600) ◽  
pp. 67-86 ◽  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
High Speed ◽  
Three Dimensional ◽  
Burning Surface ◽  
High Speed Photography ◽  
Pressure Waves ◽  
Cavity Size ◽  
Low Velocity ◽  
Liquid Explosives

A study has been made of the growth of explosion in thin films and also three-dimensional charges of liquid explosives including nitroglycerine, nitromethane‒nitric acid mixtures, hydrogen peroxide‒ethanol mixtures and diethyleneglycol dinitrate (DEGDN). Observation was by high-speed photography at microsecond framing rates. In the thin film experiments burning was initiated at the centre of the film by the rapid discharge of a condenser across a spark gap. The transition from deflagration to much faster reaction (low velocity detonation) was found to depend on the production and collapse of cavities ahead of the reaction front. Experiments with inert liquids showed that the cavitation generated in the thin film arrange­ment was produced by a surface wave propagating on the liquid/solid interface. In other ex­periments air bubbles of chosen size were deliberately inserted into the thin films. Cavities and bubbles were observed to cause transition to fast reaction in nitroglycerine and then help sustain it by various processes, namely: (i) adiabatic collapse of cavities by pressure waves from the deflagration front; (ii) presentation, of a larger burning surface to the deflagration front as it entered the cavitated liquid, (iii) jetting during the collapse which dispersed liquid droplets in the heated cavity or produced high impact pressures. The delay before transition in nitroglycerine, and the dominant process causing it, depended on the acceleration of the deflagration front and the cavity size when the front and cavities inter­acted. Transitions did not take place in the other liquid explosives with the confinements and for the propagation distances considered. In these cases the deflagration front never accelerated sufficiently to reach cavitated liquid but always propagated into homogeneous liquid in which cavities had been ‘sealed’ by pressure waves from the front. In three-dimensional charges it was possible to propagate a deflagration front into homo­geneous liquid; the reaction then progressed throughout as a deflagration. When cavities were introduced by pre-shocking, transitions to faster reaction occurred with velocities which depended on cavity size.

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.

Experimental study of hydrodynamic effects in the inverse water hydrocarbon emulsions flow in microchannels

2016 ◽  
Vol 11 (1) ◽  
pp. 30-37 ◽  
Author(s):  
A.A. Rakhimov ◽  
A.T. Akhmetov
Keyword(s):  
High Speed ◽  
Petroleum Industry ◽  
Chemical Compounds ◽  
High Viscosity ◽  
Blocking Effect ◽  
High Speed Photography ◽  
Simple Chemical ◽  
Reported Study ◽  
Dynamic Blocking ◽  
Hydrodynamic Effects

The paper presents results of hydrodynamic and rheological studies of the inverse water hydrocarbon emulsions. The success of the application of invert emulsions in the petroleum industry due, along with the high viscosity of the emulsion, greatly exceeding the viscosity of the carrier phase, the dynamic blocking effect, which consists in the fact that the rate of flow of emulsions in capillary structures and cracks falls with time to 3-4 orders, despite the permanent pressure drop. The reported study shows an increase in viscosity with increasing concentration or dispersion of emulsion. The increase in dispersion of w/o emulsion leads to an acceleration of the onset of dynamic blocking. The use of microfluidic devices, is made by soft photolithography, along with high-speed photography (10,000 frames/s), allowed us to see in the blocking condition the deformation of the microdroplets of water in inverse emulsion prepared from simple chemical compounds.

scholarly journals Prey Capturing Dynamics and Nanomechanically Graded Cutting Apparatus of Dragonfly Nymph

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 559
Author(s):  
Lakshminath Kundanati ◽  
Prashant Das ◽  
Nicola M. Pugno
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
High Speed ◽  
Prey Capture ◽  
High Speed Photography ◽  
Sensory Organs ◽  
Dragonfly Nymph ◽  
Drag Forces ◽  
Predatory Insects ◽  
Dragonfly Nymphs

Aquatic predatory insects, like the nymphs of a dragonfly, use rapid movements to catch their prey and it presents challenges in terms of movements due to drag forces. Dragonfly nymphs are known to be voracious predators with structures and movements that are yet to be fully understood. Thus, we examine two main mouthparts of the dragonfly nymph (Libellulidae: Insecta: Odonata) that are used in prey capturing and cutting the prey. To observe and analyze the preying mechanism under water, we used high-speed photography and, electron microscopy. The morphological details suggest that the prey-capturing labium is a complex grasping mechanism with additional sensory organs that serve some functionality. The time taken for the protraction and retraction of labium during prey capture was estimated to be 187 ± 54 ms, suggesting that these nymphs have a rapid prey mechanism. The Young’s modulus and hardness of the mandibles were estimated to be 9.1 ± 1.9 GPa and 0.85 ± 0.13 GPa, respectively. Such mechanical properties of the mandibles make them hard tools that can cut into the exoskeleton of the prey and also resistant to wear. Thus, studying such mechanisms with their sensory capabilities provides a unique opportunity to design and develop bioinspired underwater deployable mechanisms.

Droplet transfer behavior of narrow gap laser wire filling welding

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940045 ◽  
Author(s):  
Z. Zhang ◽  
R. Wang ◽  
G. Gou ◽  
H. Chen ◽  
W. Gao
Keyword(s):  
Welding Speed ◽  
High Speed ◽  
Transition Period ◽  
High Speed Photography ◽  
Narrow Gap ◽  
Droplet Transfer ◽  
Transfer Behavior ◽  
Feeding Speed ◽  
Wire Feeding ◽  
Droplet Transition

In this paper, we study the droplet transition behavior of narrow gap laser wire filling welding under the condition of changing welding speed and wire feeding speed, and it was observed by high-speed photography. It was found that with the increase of welding speed, the frequency of droplet transfer was reduced and the transition period was prolonged. With the increase of wire feeding speed, the wire was not fully melted and finally inserted into the molten pool.

Experimental Characterization of a Modified Airlift Pump

2014 ◽  
Author(s):  
Afshin Goharzadeh ◽  
Keegan Fernandes
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
High Speed ◽  
Water Flow Rate ◽  
High Speed Photography ◽  
Two Phase ◽  
Inner Diameter ◽  
Airlift Pump ◽  
Flow Map ◽  
Churn Flow

This paper presents an experimental investigation on a modified airlift pump. Experiments were undertaken as a function of air-water flow rate for two submergence ratios (ε=0.58 and 0.74), and two different riser geometries (i) straight pipe with a constant inner diameter of 19 mm and (ii) enlarged pipe with a sudden expanded diameter of 19 to 32 mm. These transparent vertical pipes, of 1 m length, were submerged in a transparent rectangular tank (0.45×0.45×1.1 m3). The compressed air was injected into the vertical pipe to lift the water from the reservoir. The flow map regime is established for both configurations and compared with previous studies. The two phase air-water flow structure at the expansion region is experimentally characterized. Pipeline geometry is found to have a significant influence on the output water flow rate. Using high speed photography and electrical conductivity probes, new flow regimes, such as “slug to churn” and “annular to churn” flow, are observed and their influence on the output water flow rate and efficiency are discussed. These experimental results provide fundamental insights into the physics of modified airlift pump.

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