复合固体推进剂颗粒填充模型及其统计特性分析

复合固体推进剂属于高填充比颗粒类复合材料,氧化剂和金属颗粒在基体中的随机分布使其在细观尺度具有非均质的特点。从细观尺度研究固体推进剂燃烧及力学性能时,必须考虑颗粒级配、空间分布和种类等因素的影响。采用分子动力学方法,以硝酸酯增塑聚醚高能复合固体推进剂为研究对象,将固体颗粒模型化为球形,生成其在基体内随机分布的颗粒填充模型。利用Monte-Carlo算法模拟计算颗粒填充模型细观结构的两点概率函数,并研究了颗粒填充体积分数、尺寸与级配等参数对其的影响规律。从统计意义上给出具有各态历经性、统计均匀性和各向同性特点的颗粒填充构型最小周期性代表体元尺寸,可有效减小后续研究的计算量,节约计算成本。所构建的推进剂细观几何构型及对最小周期性代表体元尺寸的计算为后续开展复合固体推进剂细观尺度燃烧、燃面处铝团聚及力学性能数值研究奠定了基础。

Particle packing model of composite solid propellant and its statistical analysis

Composite solid propellant is a kind of composite material with high packing fraction. It has the characteristic of heterogeneity in meso-scale because of the random distribution of oxidizer and metal particles in the matrix. Effects of particle gradation, spatial distribution and content must be taken into consideration while studying the combustion characteristics and mechanical property of the solid propellant in meso-scale. A random sphere packing model of nitrate ester plasticized polyether propellant based on molecular dynamics method was built. Monte-Carlo simulation was used to calculate the two-point correlation function of the random sphere pack. The effects of packing fraction, particle gradation and particle size on the two-point correlation function were studied. From the statistical significance, to obtain the minimum size of representative volume element with the characteristics of ergodicity, statistical homogeneity and isotropy can effectively reduce the calculation cost of subsequent research. The meso-scale propellant model established in this research is important and basic for the study on the complex nonlinear processes of the composite solid propellant such as combustion, decomposition, agglomeration.