Abstract

Objective China still lags behind other military powers in the application of high-pressure， high-energy propellants in rocket motors. This is primarily due to the insufficient depth and systematization in fundamental theoretical research， an incomplete understanding of the high-pressure combustion mechanisms of high-energy propellants， and limited methods for controlling their combustion characteristics under high-pressure conditions. In this paper， the combustion mechanisms of high-energy nitrate ester plasticized polyether （NEPE） propellants are investigated using advanced technical approaches， including high-pressure closed vessel tests， high-speed imaging， spectral testing， and energy calculations. It aims to reveal the regulatory mechanisms of burning rate regulators on the combustion performance of high-energy propellants and to provide technical support for their application in high-pressure solid rocket motors.

Methods A high-pressure chamber with four transparent windows was used， combined with high-speed color photography with high spatiotemporal resolution， to investigate the influence of copper-containing burning rate regulator （CuL1） on the high-pressure combustion performance， flame structure， temperature distribution， and condensed-phase particle distribution of the propellants. MATLAB software was used for flame image processing， and a reconstructed model of the propellant temperature field was obtained.

Results and Discussion The high-energy NEPE propellant used polyethylene glycol （PEG） as the binder， ammonium perchlorate （AP） and nitramine explosive （RDX） as oxidants， aluminum powder as fuel， and nitroglycerin （NG） and 1，2，4-butanetriol trinitrate （BTTN） as plasticizers. The propellant was produced using a vertical mixer and subsequently solidified. Compared to hydroxyl-terminated polybutadiene （HTPB） propellants， NEPE formulations exhibited higher burning rates and pressure exponents， primarily due to the slow decomposition of oxidants at low pressure. If the decomposition rate of oxidants under low-pressure conditions could be increased， thereby enhancing the burning rate at low pressure， the overall pressure exponent could be reduced. When doping with 1% CuL1， the decomposition peak of AP dropped from 444.7 ℃ to 339.1 ℃， a decrease of 105.6 ℃. CuL1 also catalyzed the decomposition of RDX， reducing its peak from 240.8 ℃ to 218.6 ℃， a decrease of 22.2 ℃. Consequently， the decomposition rate of oxidants increased， enhancing flame brightness near the burning surface. Without a burning rate regulator， the catalytic process relied on increasing pressure to enhance thermal feedback from the flame to the burning surface， thereby accelerating oxidant decomposition. Within the range of 1~5 MPa， the gas-phase temperature near the burning surface was consistently higher for CuL1-doped propellants， indicating more intense heat released due to enhanced oxidant decomposition. As pressure increased from 0 MPa to 15 MPa， the flame height of CuL1-containing propellant decreased slightly with a slope of 0.692 0. In contrast， the propellant without a burning rate regulator had a higher pressure exponent， and the flame height was more significantly affected by pressure， with a slope of 0.992 7. Aluminum powder underwent ignition， melting， and combustion stages. CuL1 accelerated oxidant decomposition near the burning surface， shortening the ignition-to-melting process. This led to the orderly formation of condensed-phase particles before large droplets could form， improving particle size uniformity and combustion stability. Without CuL1， the propellant aluminum powder ignited upon heating near the burning surface， resulting in significant agglomeration and a broad distribution of particle sizes. During the combustion process of CuL1-doped propellants， aluminum powder was ejected from the burning surface. Due to the high oxidant concentration near the burning surface， the melting process was shortened， facilitating the rapid formation of condensed-phase particles after ignition， resulting in relatively uniform particle sizes. This improved the particle size distribution in the combustion chamber， reducing heat accumulation caused by aluminum powder agglomeration and thereby enhancing propellant combustion stability. When CuL1 was doped， aluminum powder agglomeration was effectively controlled， thermal accumulation was suppressed， and the temperature distribution near the burning surface and in the gas-phase region was relatively more uniform. The maximum temperature reached 2 718 K. The energy barrier for the decomposition of NH₃ into NH₂*+H* decreased from 1.84 eV to -0.89 eV， and the energy barrier for its further decomposition into NH*+H* decreased from 2.64 eV to 1.52 eV.

Conclusion The continuous development of highly efficient burning rate regulators is conducive to regulating the high-pressure combustion performance of high-energy propellants. Conducting research on propellant combustion at microscopic and molecular scales can reveal more inherent mechanisms controlling propellant combustion and redox reactions.

Keywords： high-energy propellant； mechanism of high-pressure combustion； burning rate regulator； flame structure； temperature field distribution

Get Citation: LI Qiang， XIE Jingsheng， WANG Dengke， et al. Influencing mechanism of burning rate regulators on high-pressure combustion performance of high-energy solid propellants［J］. China Powder Science and Technology， 2026， 32（1）： 1-11.

Received: 2025-06-05 .Revised: 2025-06-12, Online: 2025-06-26

Funding Project: 国家国防科技工业局基础性JG科研院所稳定支持计划； 内蒙自然科学基金项目，编号 ：2021BS05014。

First Author: 李强（1992—），男，高级工程师，博士，硕士生导师，研究方向为含能材料燃烧性能调控。E-mail：1499175325@qq.com。

DOI：10.13732/j.issn.1008-5548.2026.01.017

CLC No: TB4； TQ324.8              Type Code: A

Serial No: 1008-5548（2026）01-0001-11