铝镁贫氧推进剂中铝颗粒团聚特性

为了研究铝镁贫氧推进剂中铝颗粒燃烧的团聚行为和特性,采用扫描电子显微镜和光学可视化实验方法,对铝镁贫氧推进剂的燃烧过程、铝颗粒团聚产物的微观结构和粒径进行了研究,建立了铝团聚物尺寸预测模型并与实验数据进行了拟合。结果表明,在燃烧表面形成的铝液滴团聚物脱离燃烧表面后,会发生二次团聚。在1.0 MPa下,推进剂试件燃烧较充分,铝颗粒燃烧后为光滑的球状氧化铝颗粒,镁颗粒燃烧后为白色絮状;在0.2 MPa下,推进剂试件燃烧不充分,铝颗粒没有被完全氧化,表面较粗糙。随着燃烧室压强的升高,铝团聚物的体积平均粒径D(4,3)减小,而表面积平均粒径D(3,2)增大,粒径分布趋向单峰化,说明随着压强的增加,D(4,3)和D(3,2)的值越接近,铝团聚物的形状越规则,粒径分布越集中。团聚物粒径与燃烧速率成反比。

Agglomeration Characteristics of Aluminum Particles in Aluminum-magnesium Oxygen-poor Propellant

To study the agglomeration behaviors and agglomeration characteristics of aluminum particles in aluminum-magnesium (Al-Mg) oxygen-poor propellant, the combustion process of Al-Mg oxygen-poor propellants and the microstructure and particle size of agglomeration products of Al particles were investigated by using scanning electron microscopy and optical visualization experiment method. A model for predicting the aluminum agglomeration size was established and fitted to the experimental data. Results show that the secondary agglomeration occurs after the agglomerate of aluminum droplet formed on the combustion surface is separated from the combustion surface. At 1.0 MPa, the propellant specimens burns sufficiently, the aluminum particles after burning become smooth spherical alumina particles and the magnesium particles after burning become white flocculent magnesia. At 0.2 MPa, the propellant specimens burns insufficiently, the aluminum particles are not completely oxidized and the surface is rough. With the increase of combustion chamber pressure, the volume average particle size D(4,3) of aluminum agglomerate decreases, while the surface area average size D(3,2) increases, and particle size distribution tends to single peak, indicating that with the increase of pressure, the closer the values of D(4,3) and D(3,2) are, the more regular the shape of aluminum agglomerate is, and the more concentrated the agglomeration size distribution is. The agglomerate size is inversely proportional to the burning rate.