EFFECT OF CATALYST ADDITION ON SUBATMOSPHERIC BURNING SURFACE-TEMPERATURE OF COMPOSITE PROPELLANTS

The subatmospheric burning with its higher catalytic effectiveness, lo wer temperature gradient, and slower combustion wave offers a fitting environment to study the effect of catalysts on the burning surface te mperature of composite propellants. Using platinum and platinum-13% rh odium 7.5-mu m thermocouples in uncatalyzed as well as copper-chromite -catalyzed ammonium perchlorate/hydroxyl-terminated polybutadiene comp osite propellants, the subatmospheric-burning surface temperatures wer e measured. The results of the present experimental study are in close agreement with the established trend; the surface temperature increas es with the increase in pressure. Some experimental studies of others failed to give an observable change in surface temperature with pressu re. This is argued to be because of the dimensional inadequacy of dete ctors in the very high-temperature-gradient environment. The measured surface temperature of the catalyzed propellant is significantly highe r than that of the uncatalyzed one. The study shows that the increased surface and subsurface beat release caused by catalyst addition cause s this temperature enhancement.