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.

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 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.

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.

Underwater shock wave induced by pulsed discharge on water

2021 ◽  
Author(s):  
Tomohiro Furusato ◽  
Mitsuru Sasaki ◽  
Yoshinobu Matsuda ◽  
Takahiko Yamashita
Keyword(s):  
Biological Sciences ◽  
Shock Wave ◽  
Shock Waves ◽  
Surface Discharge ◽  
Underwater Shock Wave ◽  
Mean Velocity ◽  
Combined Action ◽  
Underwater Shock ◽  
The Mean ◽  
Wave Induced

Abstract Plasmas on liquids have provided significant applications in material, environmental, and biological sciences. The mechanisms of these chemical reactions in liquids have been primarily discussed by the plasma–liquid interactions and convection by an electrohydrodynamic flow. Although shock waves play a significant role in the radical formation, agitation, and cell destruction, not much information is available on underwater shock waves induced by the surface discharge on water. In this study, an underwater shock wave generated by the pulsed surface discharge on water using the laser shadowgraph method has been demonstrated. The results reveal that the shock wave generated by the discharge on water was transmitted into the water. The mean velocity of the shock wave reached 1.7 km/s. The results indicate that the surface discharge accelerates the reaction in the water by the combined action of the underwater shock wave and the plasma reaction at the air–water interface. The results are expected to aid in the understanding the mechanisms of existing applications, such as decomposition, synthesis, and sterilization.

scholarly journals Investigation of the Propagation Characteristics of Underwater Shock Waves in Underwater Drilling Blasting

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Xin Liu ◽  
Wenbin Gu ◽  
Jianqing Liu ◽  
Zhenxiong Wang ◽  
Jinglin Xu ◽  
...  
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Linear Regression Analysis ◽  
Time History ◽  
Engineering Practice ◽  
Underwater Shock Wave ◽  
Pressure Time ◽  
Underwater Shock ◽  
Measured Pressure ◽  
Fitting Model

During the first-stage project of the main channel of Ningbo-Zhoushan Port’s Shipu Harbor, underwater shock waves were monitored. By analyzing a typical measured pressure time history curve, the characteristics of underwater shock waves in an engineering context were obtained. We obtained a traditional exponential attenuation formula for underwater shock waves based on the measured data, simplified the model of underwater drilling blasting based on engineering practice, deduced a revised formula for underwater shock wave peak overpressure on the basis of dimensional analysis, established a linear fitting model, and obtained the undetermined coefficients of the revised formula using a linear regression analysis. In addition, the accuracies of the two formulas used to predict underwater shock wave peak overpressure and the significance order of influence and influence mechanism of factors included in the revised formula on the underwater shock wave peak overpressure were discussed.

Study on Behavior of Underwater Shock Wave in Enclosed Vessel

2013 ◽  
Vol 767 ◽  
pp. 68-73
Author(s):  
Yusuke Seki ◽  
Hiroshi Fukuoka ◽  
Yoshitaka Miyafuji ◽  
Hirofumi Iyama ◽  
Osamu Higa ◽  
...  
Keyword(s):  
Shock Wave ◽  
Food Processing ◽  
Main Parameter ◽  
Peak Pressure ◽  
Focal Point ◽  
Processing System ◽  
Major Axis ◽  
Minor Axis ◽  
Underwater Shock Wave ◽  
Underwater Shock

We are developing the food processing system by using the underwater shock wave. The effect of the underwater shock wave on the pressure in the vessel is the important factor for food processing system in this research. The purpose of this study is to research the behavior of the underwater shock wave in the enclosed vessel to investigate the influence of the contour of the elliptical vessel on the pressure. In this research, we used the elliptical shape for the vessel and the explosive was used to generate the shock wave. Numerical calculation was carried out by using LS-DYNA. The ratio of the length of the major axis to minor axis of the elliptical were changed, as a main parameter. As a result, it was found that underwater shock wave was generated and propageated in the elliptical vessel following the explosion. The underwater shock wave was coverged at the focal point. At the same time, the pressure was increased by the coverged underwater shock wave at the focal point in the all elliptical vessels. It was also found that the peak pressure at the focal point was determined by the contour of the elliptical vessel.

Improvement Effect of Discharge Circuit for the Underwater Shock Wave

2013 ◽  
Vol 767 ◽  
pp. 199-204 ◽  
Author(s):  
Osamu Higa ◽  
Takumi Matsui ◽  
Ryo Matsubara ◽  
Katsuya Higa ◽  
Shigeru Itoh
Keyword(s):  
Shock Wave ◽  
Peak Pressure ◽  
Discharge Circuit ◽  
Peak Time ◽  
Underwater Shock Wave ◽  
Improvement Effect ◽  
Underwater Shock

The purpose of this research is to examine the improvement effect of discharge circuit impedances. In this research, we decreased the inductive impedance of discharge circuit, and shorted the current peak time, and increased the current peak as well. As a result, the peak pressure increased to 135 %.

scholarly journals On pressure impulse of a laser-induced underwater shock wave

2016 ◽  
Vol 808 ◽  
pp. 5-18 ◽  
Author(s):  
Yoshiyuki Tagawa ◽  
Shota Yamamoto ◽  
Keisuke Hayasaka ◽  
Masaharu Kameda
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Underwater Shock Wave ◽  
Pressure Impulse ◽  
Time Integral ◽  
Wide Range ◽  
Experimental Parameters ◽  
Pressure Peak ◽  
Underwater Shock ◽  
Spherical Shock

We experimentally examine a laser-induced underwater shock wave paying special attention to the pressure impulse, the time integral of the pressure evolution. Plasma formation, shock-wave expansion and the pressure in water are observed simultaneously using a combined measurement system that obtains high-resolution nanosecond-order image sequences. These detailed measurements reveal a distribution of the pressure peak which is not spherically symmetric. In contrast, remarkably, the pressure impulse is found to be symmetrically distributed for a wide range of experimental parameters, even when the shock waves are emitted from an elongated region. The structure is determined to be a collection of multiple spherical shock waves originating from point-like plasmas in the elongated region.

A Study on Shock Energy for Concrete Destruction Using Underwater Shock Wave

2007 ◽  
Vol 566 ◽  
pp. 225-230 ◽  
Author(s):  
Masahiko Otsuka ◽  
Naoki Okamoto ◽  
Shigeru Itoh
Keyword(s):  
Shock Wave ◽  
High Speed ◽  
Peak Pressure ◽  
Concrete Block ◽  
Metal Vapor ◽  
Metal Wire ◽  
Underwater Shock Wave ◽  
Long Duration ◽  
Discharge Duration ◽  
Underwater Shock

In this study, the destruction of concrete block using underwater shock wave generated by high current is studied. A metal wire was connected to an electrode and a high voltage impulsive current was passed through it to generate the underwater shock wave. The underwater shock wave was investigated by optical observation using a high-speed camera and pressure measurement. A comparison was made on the shock wave generated from the electrode with and without connecting it to a metal wire. The underwater shock wave generated from electrode without metal wire showed the existence of many shock waves by continuous plasma within discharge duration, and the duration of the pressure pulse was long in this case. The peak pressure of underwater shock wave generated from metal wire explosion was higher than the previous case due to the reaction of metal vapor and water, whereas the pressure duration was less. The concrete block was efficiently destructed by the effect of underwater shock pressure of high impulse. The high peak pressure and long duration are necessary for the destruction of concrete block. It is suggested that high pressure induces crack to the structure, and the long pulse duration destructs the structure.

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