Manufacture and Application of Condensed Phase Explosive Mixtures for Laser-driven Pulse Detonation

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 16360423
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Aerospace engineering
• Research Institution: Kyushu University
• Principal Investigator: NAGAYAMA Kunihito Kyushu University, Dept Aeronautics and Astronautics, Faculty of Engineering, Professor, 大学院・工学研究院, 教授 (20040446)
• Co-Investigator(Kenkyū-buntansha): TAKAHASHI Koji Kyushu University, Dept Aeronautics and Astronautics, Faculty of Engineering, Associate Professor, 大学院・工学研究院, 助教授 (10243924) ; NISHIYAMA Takashi Kyushu University, Dept Aeronautics and Astronautics, Faculty of Engineering, Research Assistant, 大学院・工学研究院, 助手 (80363381) ; KUBOTA Shiro AIST, Research Center for Explosion Safety, Researcher, 爆発安全研究センター, 研究員 (00294893)
• Project Period (FY): 2004 – 2005
• Keywords: detonation / condensed phase explosive / limiting diameter / laser ignition / DDT / detonation failure / thin film / bar coater method

Research Abstract

In the present study, we have manufactured thin film of explosive substance, which is easy and safe to handle. A series of experiments have been performed by changing the method of film preparation, etc. We adopted DDNP (diazodinitrophenol) as a main reactive component and CTA (cellulose triacetate) as a binder. They are dissolved into dichloromethane. Mixture films with thickness ranging 50 micron to 500 micron were manufactured by the bar coater method or to pour the solution into shallow tray like structure made by Teflon tape. Initiation tests of the prepared films were performed by pulse laser ablation. Maximum concentration of DDNP in the film we can prepared was 90%. Since DDNP was prepared by a small particles and not dissolved into the solution, DDNP particles tends to gather at the bottom surface, and the upper surface of the film was CTA rich. Thicker films has a laminated structure, since they are produced by repeating the pouring and drying the solution in the tray structu re. All the films we have manufactured are found to be detonated. They only deflagrate. Reaction rate increases drastically, however, if they are confined in solid plates. Reaction process depends strongly on the boundary condition. Combustion tests in air suggets to a very unique combustion process : That is, laser ablation of the film produces a lot of fragments of the DDNP particles as well as high temperature plasma plume associated with strong air shock wave. This process will last at least less than 10 micro second. After that fragments burn for a long time heating the ambient air above the thin film around 100 micro second after ablation, and finally film body begins to burn after about 1 mili second. We found this unique three stage combustion process. In the first part of the study, we manufactured thin film by bar coater method. By the dependence of the reaction rate on the film thickness, we resultantly made much thicker film. We have also found that reaction rate has a local maximum at some value of the film thickness. It is very interesting to continue research on this strange properties of the reactive thin film.