Convective Burning in Solid-Propellant Cracks

Transient combustion processes inside solid-propellant cracks can significantly affect the performance of a rocket motor. A comprehensive theoretical model has been developed to study the gas dynamics, heat transfer, and flame spreading phenomena within a single isolated crack. Calculations obtained from the theoretical mode! revealed that the infernal pressurization rate, pressure gradient, and flame propagation velocity in propellant cracks decrease as the gap width increases, the rocket chamber pressurization rate decreases, and the propellant gasification temperature increases. Additionally, the predicted flame spreading was found to decelerate in a region near the crack tip; this phenomena has been experimentally observed by others. A laboratory-size combustion chamber has been designed to establish a fundamental data base in propellant crack combustion and to verify the predicative capability of the theoretical model. Preliminary experimental data, obtained in wide cracks ( — 0.1 cm) for relatively low chamber pressurization rates, closely compares with theoretical predictions.