The particle size distribution of aluminum particles during combustion plays an important role in predicting the combustion performance of aluminized solid propellants. However, conventional models face difficulties in estimating the distributions of the agglomerated particles in propellants with novel or complex compositions. This study investigated the accuracies of the experimental techniques applied to propellant combustion to obtain the three-dimensional (3D) size distributions of agglomerated particles on the burning surface and particles in the plume. The 3D spatial distributions of aluminum particles on the burning surface and in the plume during solid aluminum composite propellant combustion were obtained using digital in-line holography (DIH) and morphological watershed image segmentation. Overall, 68,321 individual particles at distances of up to approximately 20 mm from the burning surface of the propellant were analyzed under 1 MPa pressure. The field of view results suggest that approximately 7% of the particles were detected on the burning surface, displaying a trimodal distribution in the particle size range of 30–1,200 μm, and almost all the particles (>96%) were agglomerated. The mean diameters and agglomeration fractions in the height range of 0–1 mm were larger than those in the overall combustion field; the mean diameters in this height range were similar to those of the particles on the burning surface. We found that the process of “second mergence” occurred at and up to 1 mm above the burning surface. As the height from the burning surface increased, the mean particle diameter and agglomeration fraction decreased rapidly; however, when the height exceeded 11 mm, the mean diameter did not change significantly, indicating that the particles had almost burned completely and formed condensed combustion products. Significant differences were found between the results obtained from the empirical agglomeration models and those obtained from the 3D DIH because these models were developed based on 2D data. The results presented herein further provided an insight into the agglomeration characteristics of aluminum particle combustion in composite propellants.

燃烧过程中铝颗粒的粒径分布在预测铝化固体推进剂的燃烧性能中起着重要作用。然而，常规模型在估计具有新颖或复杂组成的推进剂中附聚颗粒的分布时面临困难。这项研究调查了用于推进剂燃烧的实验技术的准确性，以获得燃烧表面上的团聚颗粒和烟羽中颗粒的三维（3D）尺寸分布。使用数字在线全息（DIH）和形态学分水岭图像分割，获得了固体铝复合推进剂燃烧过程中铝颗粒在燃烧表面和烟羽中的3D空间分布。总体来说68 在1 MPa压力下分析了距离推进剂燃烧表面最远约20 mm的321个单个颗粒。视场结果表明，在燃烧表面上检测到大约7％的颗粒，在30–1,200μm的粒径范围内显示出三峰分布，几乎所有颗粒（> 96％）都聚集了。在0-1mm高度范围内的平均直径和附聚率要大于整个燃烧场的平均直径和附聚率。在此高度范围内的平均直径类似于燃烧表面上的粒子的直径。我们发现“第二合并”过程发生在燃烧表面上方1mm处。随着距燃烧表面高度的增加，平均粒径和附聚率迅速降低。但是，当高度超过11毫米时，平均直径没有明显变化，表明颗粒几乎完全燃烧并形成凝结的燃烧产物。发现从经验集聚模型获得的结果与从3D DIH获得的结果之间存在显着差异，因为这些模型是基于2D数据开发的。本文提供的结果进一步洞察了复合推进剂中铝颗粒燃烧的团聚特性。发现从经验集聚模型获得的结果与从3D DIH获得的结果之间存在显着差异，因为这些模型是基于2D数据开发的。本文提供的结果进一步洞察了复合推进剂中铝颗粒燃烧的团聚特性。发现从经验集聚模型获得的结果与从3D DIH获得的结果之间存在显着差异，因为这些模型是基于2D数据开发的。本文提供的结果进一步洞察了复合推进剂中铝颗粒燃烧的团聚特性。