Comparative study on the characteristics of energy release, decomposition, and combustion between NEPE propellants and HTPB propellants

Energy performance is always the primary focus of solid propulsion technology development. This paper investigated the characteristics of the energy release, decomposition, and combustion of two typical propellants (NEPE propellants and HTPB propellants) using NASA-CEA calculations, thermal analysis, and an electric wire ignition combustion system. The decomposition temperature of NG, BTTN, GAP, and CL-20 in NEPE propellants were low. The decomposition products were abundant and the decomposition exotherm was large. It had a strong inhibitory effect on LTD of AP and a strong promotional effect on HTD of AP, resulting in the combination of HTD and LTD of AP into a single peak. The flame brightness of two propellants was obviously improved with pressure increasing, as was the flame expansion area, burning rate, and combustion intensity. The ignition delay time t_i decreased and the burning rate r increased. Compared to HTPB propellants, NEPE propellants had brighter flames, larger flame expansion area, more intense combustion, smaller t_i, and smaller r under the same pressure. The pressure exponent n of NEPE propellants (0.43) was larger than that of HTPB propellants (0.39). The rate of the chemical reactions and the rate of diffusion and mixing had a greater impact on the burning rate of NEPE propellants.