NO EIGENVALUE METHOD FOR COMPUTING THE BURNING RATES OF HMX PROPELLANTS

A mathematical model for a three-tiered system consisting of solid, li quid, and gas is derived for studying the combustion of HMX participan ts. The resulting nonlinear two-point boundary value problem is solved bu Newton's method with adaptive gridding techniques. In this study t he burning rate is computed as an eigenvalue, which removes the uncert ainty associated with employing evaporation and condensation rate laws in its evaluation, Results are presented for laser-assisted and self- deflagration of HMX monopropellants and are compared with experimental results. The burning rates are computed over a wide range of ambient pressures and compare well with experimental results from 1 to 90 atmo spheres. The burning rate is found to be proportional to the pressure raised to the 0.82 power, Sensitivity of the burning rate to initial p ropellant temperature is calculated and found to be extremely low, in agreement with past theoretical predictions and experimental data, Res ults for laser-assisted combustion show a distinct primary and seconda ry flame separated by a dark zone, the length of which is dependent up on the incident laser flux intensity. (C) 1998 by The Combustion Insti tute.