An Investigation on the Properties of Underwater Shock Waves Generated in Underwater Explosions of High Explosives

1997 ◽  
Vol 119 (4) ◽  
pp. 498-502 ◽  
Author(s):  
S. Itoh ◽  
Z. Liu ◽  
Y. Nadamitsu
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Numerical Simulations ◽  
Underwater Explosion ◽  
High Explosives ◽  
Underwater Shock Wave ◽  
Underwater Explosions ◽  
Expansion Test ◽  
Gas Products ◽  
Underwater Shock

A cylinder expansion test for high explosives was carried out to determine JWL parameters. Using the JWL parameters, we carried out numerical simulations of the underwater shock waves generated by the underwater explosion of the high explosives. Our results showed that the behavior of the underwater shock waves at the vicinity of the explosives differs greatly from that far from the explosives. Especially, the strength of the underwater shock wave nearby the explosive rapidly decreases due to the effect of the expansion of the gas products.

scholarly journals Fundamental Characteristics of Underwater Shock Wave due to Underwater Explosion of High Explosives.

1996 ◽  
Vol 62 (601) ◽  
pp. 3278-3283
Author(s):  
Shigeru ITOH ◽  
You NADAMITSU ◽  
Akio KIRA ◽  
Shiro NAGANO ◽  
Masahiro FUJITA ◽  
...  
Keyword(s):  
Shock Wave ◽  
Underwater Explosion ◽  
High Explosives ◽  
Underwater Shock Wave ◽  
Underwater Shock

scholarly journals Experimental Study on Peak Pressure of Shock Waves in Quasi-Shallow Water

2015 ◽  
Vol 2015 ◽  
pp. 1-13
Author(s):  
Zhenxiong Wang ◽  
Wenbin Gu ◽  
Jianqing Liu
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Peak Pressure ◽  
Small Scale ◽  
Underwater Shock Wave ◽  
Underwater Explosions ◽  
Underwater Shock ◽  
Similarity Law ◽  
Similarity Laws ◽  
Water Depths

Based on the similarity laws of the explosion, this research develops similarity requirements of the small-scale experiments of underwater explosions and establishes a regression model for peak pressure of underwater shock waves under experimental condition. Small-scale experiments are carried out with two types of media at the bottom of the water and for different water depths. The peak pressure of underwater shock waves at different measuring points is acquired. A formula consistent with the similarity law of explosions is obtained and an analysis of the regression precision of the formula confirms its accuracy. Significance experiment indicates that the influence of distance between measuring points and charge on peak pressure of underwater shock wave is the greatest and that of water depth is the least within the range of geometric parameters. An analysis of data from experiments with different media at the bottom of the water reveals an influence on the peak pressure, as the peak pressure of a shock wave in a body of water with a bottom soft mud and rocks is about 1.33 times that of the case where the bottom material is only soft mud.

scholarly journals Study of Ho:YAG Laser Generated Underwater Shock Waves and Cavity Bubble for Revascularization Therapy

2000 ◽  
Author(s):  
S. H. R. Hosseini ◽  
T. Hirano ◽  
O. Onodera ◽  
K. Takayama
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Optical Fiber ◽  
Optical Fibers ◽  
Early Stage ◽  
Underwater Shock Wave ◽  
Ho:Yag Laser ◽  
Direct Laser ◽  
Order Of Magnitude ◽  
Underwater Shock

Abstract For applying shock waves to precise medical procedures like neurosurgery, a reliable generation of micro shock waves is required. Such sensitive applications make limits on usage of conventional underwater shock wave sources like Extracoporeal Shock Waves ESW [1] or micro explosives [2]. In the present study a Q-switched Ho:YAG laser and an optical fiber are used. Advantages of this method over previous shock wave sources are two order of magnitude reduction in focusing area if compared with ESW and elimination of product gases of micro explosives. Nakahara and Nagayama [3] studied underwater shock waves emanated from surface of an optical fiber by pulse Nd:YAG laser input using shadowgraph technique. Their qualitative study limited to visualization of shock waves at its early stage. The present research aims to clarify quantitatively process of the shock wave generation by direct laser beam irradiation through optical fibers, growth and behavior of generated cavities, and structure of heat induced flow in front of the optical fiber.

High Pressure Generation Using Underwater Explosion of a Spiral Explosive in a Conical Vessel

2004 ◽  
Vol 126 (2) ◽  
pp. 258-263
Author(s):  
Toru Hamada ◽  
Shigeru Itoh ◽  
Kenji Murata ◽  
Yukio Kato
Keyword(s):  
Shock Wave ◽  
Characteristic Curve ◽  
Three Dimensional ◽  
Underwater Explosion ◽  
Initial Pressure ◽  
Maximum Pressure ◽  
Underwater Shock Wave ◽  
Expansion Curve ◽  
Underwater Shock ◽  
Manganin Gauge

An explosive configuration was studied so that the underwater shock wave converges at the tip of the explosive, and a three-dimensional spiral configuration was obtained. This spiral configuration need to be analyzed theoretically due to the relation of propagation velocity of underwater shock wave, detonation velocity of the explosive and a configuration of vessel to charge the explosive. In order to study an effect of the convergence, pressure measurement at the spiral center was carried out by using a manganin gauge. Therefore, when SEP was used in this experiment, the maximum pressure value was 17.7 GPa. This maximum pressure value is higher than the pressure value of underwater shock wave generated from the underwater explosion of a straight configuration. Furthermore, this maximum pressure value was higher than C-J pressure of SEP. An initial pressure of underwater shock water shock wave that can obtain from an isentropic expansion curve of SEP and a characteristic curve of water is 5.7 GPa, and C-J pressure of SEP is 15.9 GPa. From the above-mentioned, the effect of spiral convergence could be shown well.

On Generation of Ultra-High Pressure by Converging of Underwater Shock Waves

1998 ◽  
Vol 120 (1) ◽  
pp. 51-55 ◽  
Author(s):  
S. Itoh ◽  
S. Kubota ◽  
S. Nagano ◽  
M. Fujita
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Detonation Wave ◽  
Simulation Method ◽  
Ceramic Materials ◽  
Underwater Shock Wave ◽  
Water Chamber ◽  
Metallic Compounds ◽  
Underwater Shock ◽  
Graph System

The characteristics of a new assembly for the shock consolidation of difficult-to-consolidate powders, such as inter-metallic compounds or ceramic materials, were investigated by both the experimental method and numerical simulation method. The assembly consists of an explosive container, a water chamber, and a powder container. Once the explosive is detonated, a detonation wave occurs and propagates, and then impinges on the water surface of the water chamber. After that, there occurs immediately an underwater shock wave in the water chamber. The underwater shock wave interacts with the wall of the chamber during its propagation so that its strength is increased by the converging effect. We used the usual shadow graph system to photograph the interaction process between detonation wave and water. We also used a Manganin piezoresistance gage to measure the converged pressure of the conical water chamber. Finally, we numerically investigated, in detail, the converging effects of the various conical water chambers on the underwater shock waves. The experimental results and the correspondingly numerical results agree quite well with each other.

Effects of Steel Case on Underwater Shock Wave

2011 ◽  
Vol 52-54 ◽  
pp. 943-948
Author(s):  
Ji Li Rong ◽  
Da Lin Xiang ◽  
Jian Li
Keyword(s):  
Shock Wave ◽  
Peak Pressure ◽  
Underwater Explosion ◽  
Steel Shell ◽  
Cylindrical Charge ◽  
Underwater Shock Wave ◽  
Shock Wave Energy ◽  
Lag Effect ◽  
Underwater Shock ◽  
Different Thickness

The effects of steel case confinement for the aluminized explosive on underwater explosion(UNDEX) were experimentally and numerically investigated. The experimental results using 1kg cylindrical charge cased 6mm steel shell, show that steel case enhance the peak pressure, impulse, shock wave energy and decay time relative to the bare charge. The effect of different thickness of steel case was analyzed. With the increase of the case thickness, the shock wave were enhanced first and weaken later, and there is a lag-effect for the peak pressure of shock wave. There is an optimal case thickness which could maximum enhance the peak pressure. According to dimensional analysis, it's found that the ratio of case mass and charge mass( ) is a better dimensionless parameter to estimate UNDEX for a cased charge.

Basic Study on the Crushing of Frozen Soil by Shock Loading

2007 ◽  
Author(s):  
Toshiaki Watanabe ◽  
Hironori Maehara ◽  
Masahiko Otsuka ◽  
Shigeru Itoh
Keyword(s):  
Shock Wave ◽  
High Speed ◽  
Shock Loading ◽  
Underwater Explosion ◽  
Frozen Soil ◽  
High Speed Camera ◽  
Underwater Shock Wave ◽  
Basic Study ◽  
Underwater Shock ◽  
A New Technique

The aim of study is to confirm a new technique that can crush the frozen soil and/or ice block using underwater shock wave generated by the underwater explosion of explosive. This technique can lead to the earlier sowing, which can have the larger harvest because the duration of sunshine increases. Especially, in Hokkaido prefecture, Japan, if the sowing is carried out in April, we can expect to have 150% of harvest in the ordinary season. This technique is effective against the cold regions. For example, Korea, China, Mongolia, Russia, Norway, and Sweden, etc. At first, we carried out experiments usung a detonating fuse and ice block. The process of ice breaking was observed by means of a high-speed camera. In order to check about that influence we tried to give an actual frozen soil a shock wave.

Influence of Pressure Vessel Shape on Explosive Forming

2018 ◽  
Author(s):  
Hirofumi Iyama ◽  
Masatoshi Nishi ◽  
Yoshikazu Higa
Keyword(s):  
Shock Wave ◽  
Pressure Vessel ◽  
Underwater Explosion ◽  
Metal Plate ◽  
Reflected Shock Wave ◽  
Underwater Shock Wave ◽  
Reflected Shock ◽  
Final Deformation ◽  
Underwater Shock ◽  
Explosive Forming

The explosive forming is a characteristic forming method. This technique is a metal forming using an underwater shock wave. The underwater shock wave is generated by underwater explosion of the explosive. The metal plate is formed with involving the high strain rate on this technique. In generally, the pressure vessel is used in this method due to the effective utilization of the explosion energy. The underwater shock wave is propagated in water and reflected on inside wall of the pressure vessel. This reflected shock wave is affected on the deformation shape of a metal plate. Therefore, the inside shape of pressure vessel is often changed. In other words, the shape of pressure vessel is changed, the shock pressure distribution on the metal plate and it is possible that final deformation shape of the metal plate is changed. Some numerical simulations and experiments have been carried out to clear the influence of the inside shape of pressure vessel in the explosive forming. This paper is included the results and discussions on the numerical simulation and experiment used those conditions.

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