Propagation of Underwater Shock Wave and Gas Bubble Behavior Induced by Electrical Discharge in Water

2014 ◽  
Vol 566 ◽  
pp. 403-408
Author(s):  
Hideki Hamashima ◽  
Seisaku Iwasa ◽  
Hironori Maehara ◽  
Shigeru Itoh ◽  
Kazuyuki Hokamoto
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Electrical Discharge ◽  
High Speed ◽  
Optical Observation ◽  
Gas Bubble ◽  
Bubble Behavior ◽  
Underwater Shock Wave ◽  
Whole Process ◽  
Underwater Shock

The basic behavior during underwater electrical discharge up to 10 kJ stored energy is investigated through both numerical analysis and optical-observation experiments. Since the authors have been investigating the use of underwater exploding phenomena for food processing and other applications, it is necessary to know the whole process which may affect the quality of the samples recovered. In the present investigation, the propagation of underwater shock wave was measured using a high-speed camera and compared with the numerically simulated results using LS-DYNA. Also, the motion of gas bubble, which is induced quite after the propagation of the shock wave, was measured and compared with the numerical simulation using the same code. The pressure of the bubble is not such high as the shock wave, but it is known that the impulse is not possible to be ignored due to its relatively long duration of the pressurization. Through a series of optical-observation experiments, it is confirmed that the numerical simulation is potentially possible to predict the whole phenomena for processing foods and other materials.

Numerical Simulation of Electrical Discharge Characteristics Induced by Underwater Wire Explosion

2018 ◽  
Vol 910 ◽  
pp. 72-77
Author(s):  
Ryo Henzan ◽  
Yoshikazu Higa ◽  
Osamu Higa ◽  
Ken Shimojima ◽  
Shigeru Itoh
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Electrical Discharge ◽  
Electrical Energy ◽  
Underwater Shock Wave ◽  
Discharge Characteristics ◽  
Wire Explosion ◽  
Electrical Wire ◽  
Electrical Wire Explosion ◽  
Underwater Shock

The underwater shock-wave phenomenon has been applied in various fields such as manufacturing and food processing and was investigated using many experimental and numerical analyses in the past. An underwater shock-wave is produced by various methods, e.g., underwater wire explosion and pulse-gap electrical discharge. Therefore, clarifying the shock characteristics depending on the stored electrical energy, wire dimension and material is extremely important. However, predicting the pressure and its distribution induced by underwater electrical wire explosion is hard because the phenomena associated with an elementary process are significantly complicated. In this study, to predict the discharge characteristics induced by underwater electrical wire explosion, numerical simulation based on the “simplified model of underwater electrical discharge” was performed. The numerical results show good agreement with the experimental ones.

Deformation Mechanism of Metal Plate on Explosive Forming

2005 ◽  
Author(s):  
Hirofumi Iyama ◽  
Takeshi Hinata ◽  
Shigeru Itoh
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
High Speed ◽  
Underwater Explosion ◽  
Metal Plate ◽  
Sufficient Accuracy ◽  
Underwater Shock Wave ◽  
Underwater Shock ◽  
Explosive Forming ◽  
Forming Methods

The explosive forming is one of the forming methods of a metal plate performed since the 1950s. This method is different from usual static press forming. The metal plate is accelerated by underwater shock wave, which is generated by underwater explosion of an explosive. In order to deform a metal plate in predetermined form with sufficient accuracy using this forming method, it is important to grasp the mechanism. At first, it is necessary to grasp that an underwater shock wave spreads and it collides with the metal plate. And it is also necessary to show clearly what deformation of the metal plate with high-speed. Then, we investigated about the mechanism in the numerical simulation. In this research, LS-DYNA, which is the software for shock analysis was used. Moreover, the experiment was also conducted in order to confirm whether this numerical simulation is exact.

Numerical Simulation on Explosive Welding Process Using Reflected Underwater Shock Wave

2007 ◽  
Vol 566 ◽  
pp. 309-314
Author(s):  
Kazumasa Shiramoto ◽  
Masahiro Fujita ◽  
Yasuhiro Ujimoto ◽  
Hirofumi Iyama ◽  
Shigeru Itoh
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Explosive Welding ◽  
Welding Process ◽  
Underwater Shock Wave ◽  
Underwater Shock ◽  
Effective Use

The paper describes a numerically simulated result for the explosive welding using reflected underwater shock wave. Through the numerical simulation, the effective use of reflected underwater shock wave was clearly suggested and the method to improve the assembly was demonstrated.

Behavior of Bubble in Small Water Tank Used for Food Processing Using Underwater Shock Wave

2011 ◽  
Vol 673 ◽  
pp. 225-230 ◽  
Author(s):  
Hideki Hamashima ◽  
Manabu Shibuta ◽  
Shigeru Itoh
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Food Processing ◽  
High Speed ◽  
Underwater Explosion ◽  
Video Camera ◽  
Experimental Result ◽  
Water Tank ◽  
Underwater Shock Wave ◽  
Small Water

The food processing technology using a shock wave can prevent deterioration of the food by heat because it can process food in a short time. Generally, since the shock wave used for food processing is generated by underwater explosion, the load of a shock wave to the food becomes very complicated. Therefore, in order to process safely, it is important to clarify the behaviors of the shock wave and the bubble pulse generated by underwater explosion. In this research, in order to investigate the behavior of the shock wave in the water tank used for food processing, the optical observation experiment and the numerical simulation were performed. In the experiment, the shock wave generated by underwater explosion was observed with the high-speed video camera. The numerical simulation about the behavior of bubble pulse was performed using analysis software LS-DYNA. Comparing and examining were performed about the experimental result and the numerical simulation result. The result of the numerical simulation about the behavior of the shock wave generated by underwater explosion and the shock wave generated by the bubble pulse and the bubble pulse was well in agreement with the experimental result.

A Study of Developing Composite Material of Penetrated Diamond Particles Into Metal Plate

2009 ◽  
Author(s):  
Keijiro Nishi ◽  
Shigeru Tanaka ◽  
Shigeru Itoh
Keyword(s):  
Thermal Conductivity ◽  
Shock Wave ◽  
Composite Material ◽  
High Speed ◽  
High Hardness ◽  
Optical Microscope ◽  
Metal Plate ◽  
Underwater Shock Wave ◽  
Diamond Particles ◽  
Underwater Shock

An explosive welding technique which uses underwater shock wave to weld thin aluminum plate has been studied and the technical advantages were reported. In this research, we propose a method to produce a composite material using an underwater shock wave generated by detonation of explosive. In the production process, a metal plate (flyer plate) accelerates to a high speed by the underwater shock wave, and collided with diamond particles and penetrated the metal plate. Diamonds were used as the particles and aluminum plates (A1050) as the flyer plates. Diamond has high hardness and excellent thermal conductivity, therefore diamond should provide improvement in the thermal conductivity of the composite material. From recovered sample, the multilayer joined surface including diamond particles was observed using an optical microscope. The production of the pipe of composite materials was attempted using this technique as the application. Details of the experimental methods and results are reported in this paper.

New Technique for “Cullet” Generation of Glass Bottles by Using Underwater Shockwave

2006 ◽  
Vol 326-328 ◽  
pp. 1551-1554
Author(s):  
Hidetoshi Sakamoto ◽  
Shinjiro Kawabe ◽  
Kazuo Satoh ◽  
Masahiro Himeno ◽  
Shigeru Itoh
Keyword(s):  
Shock Wave ◽  
High Speed ◽  
Fracture Process ◽  
Image Converter ◽  
Glass Bottle ◽  
Underwater Shock Wave ◽  
Application Technique ◽  
System A ◽  
Underwater Shock ◽  
Glass Bottles

As the application technique for glass bottle’s recycling system, a new “Cullet” generation method by using underwater shock wave was proposed. This small fragmentation technique of glass bottles has a lot of excellent advantages such as the simplification of process by simultaneous cleaning and crushing operation, the high collect rate of “Cullet” and so on. In this study, the relation between of the explosive conditions and “Cullet” sizes were clarified and the high speed fracture process of glass bottle was observed by framing photograph of high speed image converter.

Exfoliation of Marine Organisms Technology by Using Underwater Shock Wave

2005 ◽  
Author(s):  
Toshiaki Watanabe ◽  
Hirofumi Iyama ◽  
Ayumi Takemoto ◽  
Shigeru Itoh
Keyword(s):  
Shock Wave ◽  
High Speed ◽  
Marine Organisms ◽  
High Speed Camera ◽  
Sluice Gate ◽  
Underwater Shock Wave ◽  
Manual Operation ◽  
Fluid Resistance ◽  
Personnel Expenses ◽  
Underwater Shock

Adhesion problem of marine organisms often becomes a problem, in the case of ship, marine floating construction and sluice gate of power plant. These make fluid resistance of a hull increase, cause a buoyancy fall, or cause reducing coolant etc. Although these are chiefly removed by manual operation now, immense expense and immense labors, such as personnel expenses and time and effort, are needed. We tried application of an underwater shock wave, in order to solve these problems. Interference of a shock wave and the mechanism of marine organisms exfoliation were explored using the explosive and PMMA plate, which imitated a marine organisms adhesion. The process of exfoliation of organisms from PMMA plate was observed by using of the high-speed camera.

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