Investigation on unsteady thermal process of NEPE propellant based on an refined chemical kinetic model

Abstract

This study presents a sophisticated investigation into the intricate heat and mass transfer mechanisms of NEPE composite propellant under realistic rocket motor conditions, with particular emphasis on the rapid depressurization effects. To accomplish this, we have developed an innovative particle packing algorithm coupled with a novel semi-global kinetics model. By integrating detailed chemical kinetics models for Ammonium perchlorate (AP) oxidizing powders, Cyclotetramethylene tetranitramine (HMX) oxidizing powders, and Nitroglycerin/1,2,4-Butane triol trinitrate (NG/BTTN) fuel-binder, we have constructed a meso-scale model of NEPE propellant based on comprehensive experimental data. Furthermore, a refined 9-step kinetic mechanism has been incorporated into the meso-scale model, along with a pressure drop model that accurately captures the intricate gas reaction domain. The predicted parameters of NEPE propellant have been meticulously compared with experimental results, demonstrating a remarkable level of agreement. Moreover, meticulous analyses have been carried out to investigate the complex thermal processes exhibited by this composite propellant under the challenging conditions of rapid depressurization combustion. These analyses primarily focus on unraveling the dynamic evolution of the gas-solid phase and the underlying thermal regression mechanism of the solid phase. Notably, our findings reveal intriguing temporal changes in local heat flux feedback spikes throughout the entire depressurization process, owing to the intricate topology structure of NEPE propellant, which comprises multiscale oxidizing micro-particles embedded within a fuel-binder matrix. This research significantly enhances our understanding of the thermal behavior and performance characteristics of NEPE composite propellant, thereby paving the way for future advancements in rocket propulsion technology.