Dayu Ding, Morimasa Higaki, Yuzo Ooki, and Tadao Yoshida*
Abstract: Firing firework star experiments have been carried out using 20 mm and 25 mm inner diameter steel mortars equipped with two or four pressure transducers, and the pressure profi les were recorded. The relative pressure profiles of the four positions in the mortar changed with the gap ratio between sectional areas of the star and the mortar wall, and with the mass of the lifting charge. The maximum pressure attained decreased and the scatter of observed data increased with an increase of the gap ratio. It was shown by experiment using four pressure transducers that, when the gap ratio is large, the pressures to the rear and front of a star should be corrected for the pressure distribution in the mortar. In the first half of the experiment, using two pressure transducers the muzzle velocity of a star was estimated from the pressure profile of the bottom transducer. When the gap between star and mortar wall and the mass of lifting charge were small, the calculated and observed muzzle velocities agreed well. However, in the case of a large gap, the calculated value was larger than the observed one. In the latter half of the experiment, four pressure transducers were used and it was found that in the case of a large gap the pressure profile from the bottom transducer did not give the real pressures to the rear and front of the star in the mortar. A correction for the difference was tried and the agreement between the observed and calculated values was improved.
Keywords: fireworks, interior ballistics, pressure profile, muzzle velocity
Ref: JPyro, Issue 22, 2005,pp52-62
(J22_52)
© Journal of Pyrotechnics and CarnDu Ltd
