Flame structure of composite pseudo-propellants based on nitramines and azide polymers at high pressure

Abstract

The chemical and thermal structures of flame of composite pseudo-propellants based on cyclic nitramines (HMX, RDX) and azide polymers (GAP and BAMO–AMMO copolymer) were investigated at a pressure of 1.0 MPa by molecular beam mass spectrometry and a microthermocouple technique. Eleven species H 2, H 2O, HCN, CO, CO 2, N 2, N 2O, CH 2O, NO, NO 2, and nitramine vapor (RDX v or HMX v), were identified, and their concentration profiles were measured in HMX/GAP and RDX/GAP pseudo-propellant flames at a pressure of 1 MPa. Two main zones of chemical reactions in the flame of nitramine/GAP pseudo-propellants were found. In the first, narrow, zone 0.1 mm wide (adjacent to the burning surface), complete consumption of nitramine vapor and NO 2 with the formation of NO, HCN, CO, H 2, and N 2 occurs. In the second, wider high-temperature zone, oxidation of HCN and CH 2O by NO and N 2O with the subsequent formation of CO, H 2, and N 2 takes place. The leading reactions in the high-temperature zone of flame of nitramine/GAP pseudo-propellants are the same as in the case of pure nitramines. In the case of nitramine/BAMO–AMMO pseudo-propellants a presence of carbonaceous particles on the burning surface did not allow us to analyze the zone adjacent to the burning surface, therefore only one flame zone was found. Temperature profiles in the combustion wave of nitramine/azide polymer pseudo-propellants were measured at 1 MPa. The data obtained can be used to develop and validate a self-sustain combustion model for pseudo-propellants based on nitramines and azide polymers.