Theory of Flame Front Propagation in Porous Propellant Charges under Confinement

Abstract : Ultra-high burning rates can be achieved by combustion of porous media. A theoretical model is developed to describe the flame propagation in a packed bed of granular propellant. The calculated pressure-time-distance transients, wave propagation speed, and mass fraction of propellant burned during flame propagation, all agree well with experimental data obtained for the same conditions. Results demonstrate that the combustion-generated strong pressure gradient causes the hot product gas to deeply penetrate the unburned region. A continental divide forms automatically in the pressure distribution as the wave progresses into the charge. In the particular case studied the flame front reaches a speed about 5000 times the normal propellant burning rate and continues to accelerate as the internal pressure increases. (Modified author abstract)