A study on characteristics of combustion of low burning rate composite propellant for base drag reduction

摘要

Combustion characteristics of AP/HTPB composite solid propellant was studied in order to obtain the optimized propellant composition with high performance for base bleed applications. The average molecular weight of the composite propellant, which was calculated by PEP code, decreased with decrease of Ammonium Perchlorate (AP) content. The flame temperature increased with increase of Ammonium Perchlorate content. For the base combustion of fuel-rich solid propellant, however, the combustion products in the near wake region can cause a secondary combustion with a freestream air, so that higher temperature can be kept further downstream of base. It was observed that the propellant composition including 5 percent oxamide has the ignition delay of 1.5 sec compared with that including 0.5 percent oxamide. Therefore the attention is required in case of using oxamide as the additive of base bleed propellant though it is the effective burning rate modifier. Adding aluminum in propellant composition increased the burning rate considerably without increasing the base bleed effect, resulting in decreased range performance. The slightly higher temperature did not compensate for the shorter burning time. The burning rate augmentation generally decrased with decreased AP particle size, but this relatioship was dependant on the binder system and spin rate.