著者

Chihiro Inoue Ryo Nishiyama Yasuhiro Fujisaki Toshiaki Kitagawa

出版者

Japan Explosives Society

雑誌

Science and Technology of Energetic Materials (ISSN:13479466)

巻号頁・発行日

vol.81, no.5, pp.121-127, 2020 (Released:2020-11-09)

---

A traditional Japanese sparkler, senko-hanabi, is consists of paper string wrapping 0.1 g of black powder. The sparkler requires heat production by combustion of contained charcoal with ambient oxygen, showing off beautiful sparks luminous by heat radiation. In the present study, the appearance of the sparks is investigated under various ambient conditions, in which the total pressure is from vacuum to 5.0 bar and the oxygen concentration rate is set up to 40 %. The sparkler is ignited by Joule heating inside a closed vessel. Profound effects are confirmed by the ambient conditions on the sparks. As the total pressure rises, sparks spread actively, because the boundary layer surrounding the fireball, created at the bottom end of the paper string, becomes thinner, and the amount of oxygen supply increases. The oxygen concentration rate directly contributes to the amount of oxygen supply. The criterion given by molar flux of oxygen supply to the fireball is identified as 10-1 mol · s-1 · m-2, rate-controlled by molecular diffusion through the boundary layer, for embodying fragile beauty over the centuries.

著者

Ryojiro Minato Shigeru Tanaka

出版者

Japan Explosives Society

雑誌

Science and Technology of Energetic Materials (ISSN:13479466)

巻号頁・発行日

vol.83, no.4, pp.111-116, 2022 (Released:2022-09-09)

---

The present study explores the explosion risk of nitromethane in fluid hammer phenomena. Nitromethane flowed through the flowpath by the gas-pressurized feed method in this test. The tank pressure conditions are 0.4, 0.6, 0.8 and 0.95 MPaG. No explosion occurred in any case in the present study. The fluid hammer test of water is also conducted to compare with nitromethane. The experimental peak pressure is 5.15 MPaG, and the fluid hammer pressure rise is 4.59 MPaG in the tank pressure condition of 0.95 MPaG. The experimental pressure rise of nitromethane is close to the theoretical prediction given by the Joukowsky equation in the flow velocity condition of more than 3.0 m・s-1 if the pressure propagation velocity is equal to the sonic speed. The peak pressure of the fluid hammer effect for water is the same with or higher than nitromethane. The other experimental fluid hammer test data indicates that nitromethane has similar fluid dynamic behaviors to water. Thus, the present investigation recommends using water for the fluid hammer test of the nitromethane feed system.

著者

Thomas de Prinse David Armitt Ben Rogers Nigel A. Spooner

出版者

Japan Explosives Society

雑誌

Science and Technology of Energetic Materials (ISSN:13479466)

巻号頁・発行日

vol.83, no.3, pp.65-70, 2022 (Released:2022-07-06)

---

Samples of trinitrotoluene (TNT) and erythritol tetranitrate (ETN) were exposed to nanosecond pulses from a tunable laser source across 90 minutes. During this continued laser pulse exposure, the samples of TNT underwent heavy degradation while the samples of ETN were able to resist high energy densities without visible alteration. A degradation pathway involving a nitro-nitrite rearrangement is suggested for the TNT, which sees radical production result in carbon ‘char’ formation in the explosive, despite there being no signs of bulk or surface melting. The formation of this carbonexplosive mixture and its implications towards the safety of extended exposure laser sensing techniques is discussed.

著者

近内 亜紀子 浅地 哲夫 能美 仁 小田野 直光

出版者

火薬学会

雑誌

Science and Technology of Energetic Materials : journal of the Japan Explosive Society (ISSN:13479466)

巻号頁・発行日

vol.70, no.3, pp.55-61, 2009-08-31

参考文献数

16

著者

鈴木 健

出版者

火薬学会

雑誌

Science and technology of energetic materials : Journal of the Japan Explosives Society (ISSN:13479466)

巻号頁・発行日

vol.75, no.3, pp.91-98, 2014