BURN RATE AUGMENTATION OF COMPOSITE PROPELLANT ADJACENT TO INSULATION MATERIALS

摘要

Bristol manufactures several small solid propellant rocket motors using a composite HTPB/AP based propellant system. Most Bristol rocket motors developed prior to 1990 used an internal insulation system consisting of an asbestos-filled roll-form butadiene (RF/B) case insulation material, with an aluminum liner between the propellant and the insulation. Due to health and safety regulations, processing of asbestos containing insulation materials is no longer permissible. The RF/B insulation system has been replaced with alternate insulation systems which use a Bristol proprietary carbon-filled (CF/P) liner to interface with the propellant. The CF/P liner uses the same polymer system as the propellant, and provides limited insulating capabilities as well as promoting case bonding of the propellant. Motors using the CF/P liner system have shown an augmentation in the propellant burning rate prior to motor tail-off compared to their previous RF/B insulated versions. The performance changes are attributed to a localized augmentation of the propellant burning rate adjacent to the CF/P liner interface. This paper will discuss potential mechanisms for the burning rate augmentation effect, and describes the results of testing and analyses performed to evaluate the phenomenon.