Development of a Laboratory-Scale System for Hybrid Rocket Motor Testing

摘要

The results of efforts to establish a laboratory-scale setup for hot-fire testing of a modular hybrid rocket motor and experimental evaluation of the effect of several additives on the regression rates of hydroxyl-terminated-polybutadiene-based fuels are presented. Supercharged nitrous oxide was used as the oxidizer in all tests. The main objectives of the reported test-program phase were the design and buildup of the experimental facility and to sort out, by hot-fire tests, various fuel compositions with respect to the fuel regression rate and combustion-extinction ability at oxidizer shutoff. The cartridge-loaded fuel grains had an initial circular port diameter of 42 mm, a length of 400 mm, and a web thickness of 15 mm. Five fuel composition families with various additive contents of fine ammonium perchlorate, polystyrene, and a burning-rate catalyst were tested. The fuel regression rate increased with the increase in the ammonium perchlorate portion, but combustion extinguishment was not possible with high ammonium perchlorate content. A significant enhancement of the regression rate of up to 3.5 mm/s at an average oxidizer mass flux of about 140 kg/m~2 ? s (0.2 Ibm/in~2 ? s) was obtained with the addition of both fine ammonium perchlorate and large particles of polystyrene. Full combustion extinguishment and multipulse operation with an insignificant effect on the regression rate was demonstrated by the use of large particles of polystyrene additive and no addition of ammonium perchlorate.