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Science and Technology of Energetic Materials

Vol.67, No.5 (2006)

Research paper

Internal ballistics of fireworks shell and star (*in Japanese)
Dayu Ding, Masamori Higaki, Yuzo Ooki, and Tadao Yoshida
p.164-170

Abstract

There is a gap between shell and inner surface of a mortar used for lifting a fireworks shell because the inner diameter of the mortar is larger than that of the fireworks shell. A combustion gas of lifting charge leaks through the gap and the amount of gas leakages increases with the increase of the gap cross-sectional area. Meanwhile, the amount of gas leakages passing through the gap also changes with a pressure from the combustion gas of lifting charge in the mortar.
Two pressure profiles at bottom and upper location in a mortar respectively were measured and the effects of the combustion gas leakages on the internal ballistics were discussed in this work.
It was found that the amount of gas leakages passing through the gap could be qualitatively explained by the relationship of two pressure profiles at bottom and upper in the mortar. The pressure is not uniform on both the combustion side and the opposite side of a projectile, so that the pressure acting on the surface of the projectile does not equal to that measured at the bottom of the mortar when the amount of the gas leakages is large. If the amount of the gas leakages is small, the calculated internal ballistics by the pressure profile in the mortar agrees well with the experiment results.

Keywords

Fireworks, Iinternal ballistics, Mortar, Projectile, Pressure profile

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