Tu Chengyin, Chen Xiong, Chen Fan, Zhuang Yuqian, Cai Wenxiang, Li Yingkun, Li Weixuan, Zhou Changsheng, Xie Renjie
School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, People's Republic of China.
Wuhan Guide Infrared Co.,Ltd., Wuhan, 430205, People's Republic of China.
Sci Rep. 2024 Aug 22;14(1):19462. doi: 10.1038/s41598-024-70168-1.
Aluminum (Al) is usually added to solid propellants to improve the combustion performance, however the condensed combustion products (CCPs) especially the large agglomerates generated from aluminum combustion can reduce the specific impulse of the engine, and result in two-phase loss, residue accumulation and throat liner ablation. Al and ammonium perchlorate (AP), as important components of NEPE propellants, can affect the formation process of the CCPs of aluminized NEPE propellants. To clarify the effect of Al and AP particle sizes on the properties of the CCPs of aluminized NEPE propellants, a constant-pressure quench vessel was adopted to collect the combustion products of four different formulations of NEPE propellants. It was found that the condensed combustion products are mainly divided into aluminum agglomerates and oxide particles, the diameter of the aluminum agglomerates of these four different formulations of NEPE propellants at 7 MPa was smaller than that in 3 MPa, and the shells of the aluminum agglomerates were smoother and the spherical shape was more perfect. X-ray diffraction analysis of the CCPs of the four NEPE propellants under 3 MPa revealed the presence of both Al and AlO. With the increase of the particle size of Al and AP, the oxidation degree of aluminum particles decreases. The particle size of the CCPs of the four different formulations of NEPE propellants under 1 and 3 MPa was analyzed by using a laser particle size analyzer, it is found that the increase of AP particle size is helpful to reduce the size of condensate combustion products. Based on the classical pocket theory, establishing a new agglomeration size prediction model, which can be used to predict the agglomeration size on the burning surface. Compared with the empirical model, the new agglomeration size prediction model is in good agreement with the experimental results.
通常会在固体推进剂中添加铝（Al）以改善燃烧性能，然而凝聚燃烧产物（CCPs），尤其是铝燃烧产生的大团聚物，会降低发动机的比冲，并导致两相损失、残渣堆积和喉部衬套烧蚀。铝和高氯酸铵（AP）作为NEPE推进剂的重要成分，会影响含铝NEPE推进剂CCPs的形成过程。为了阐明铝和AP粒径对含铝NEPE推进剂CCPs性能的影响，采用恒压淬熄容器收集了四种不同配方NEPE推进剂的燃烧产物。研究发现，凝聚燃烧产物主要分为铝团聚物和氧化物颗粒，这四种不同配方的NEPE推进剂在7MPa下的铝团聚物直径小于在3MPa下的直径，且铝团聚物的外壳更光滑，球形更完美。对3MPa下四种NEPE推进剂的CCPs进行X射线衍射分析，发现同时存在Al和AlO。随着Al和AP粒径的增加，铝颗粒的氧化程度降低。利用激光粒度分析仪分析了1和3MPa下四种不同配方NEPE推进剂CCPs的粒径，发现AP粒径的增加有助于减小凝聚燃烧产物的尺寸。基于经典的口袋理论，建立了一个新的团聚尺寸预测模型，可用于预测燃烧表面的团聚尺寸。与经验模型相比，新的团聚尺寸预测模型与实验结果吻合良好。
