AN EIGENVALUE METHOD FOR COMPUTING THE BURNING RATES OF RDX PROPELLANTS

A mathematical model for a three-tiered system consisting of solid, li quid and gas is derived for studying the combustion of RDX propellants . The resulting nonlinear two-point boundary value problem is solved b y Newton's method with adaptive gridding techniques. In this study the burning rate is computed as an eigenvalue, which can remove the uncer tainty associated with employing evaporation and condensation rate law s in its evaluation. Results are presented for laser-assisted and self -deflagration of RDX monopropellants and are compared with experimenta l results. The burning rates are computed over a wide range of ambient pressures and compare well with experimental results from one to nine ty atmospheres. The burning rate is found to be proportional to the pr essure raised to the 0.76 power. Sensitivity of the burning rate to in itial propellant temperture is calculated and found to be extremely lo w, in agreement with past theoretical predictions and experimental dat a. Results for laser-assisted combustion show a distinct primary and s econdary flame separated by a dark zone, the length of which is depend ent upon the incident laser flux intensity.