硼颗粒点火燃烧模型求解及影响因素分析

Numerical Model Solution and Analysis of Effect Factors of Boron Ignition and Combustion Behaviors

关键词:  固体推进剂  硼  点火  燃烧  动力学模型

Key words:  Solid propellant  Boron  Ignition  Combustion  Kinetic model

摘要:

简要介绍了含氧气和水蒸气环境下硼颗粒点火动力学模型和燃烧动力学模型，并给出了详细的数值求解方法，采用权威实验数据校验模型的合理性和准确性。利用模型预测硼颗粒点火燃烧特性，分析表面氧化层厚度，粒径，环境压强，氧分压，水蒸气分压及环境温度等因素对硼的点火燃烧特性的影响，并与相应的实验结果进行比较。结果显示，硼颗粒点火时间和燃烧时间均随粒径增大而增加。当粒径小于20μm时，燃烧时间与粒径基本呈正比关系。而当粒径大于20μm时，燃烧时间随粒径增大呈二次方增长。点火时间随初始氧化层厚度增加单调递增，增长率达到65ms/μm。点火时间和燃烧时间随环境压强增大基本呈现减小的趋势，但3MPa以上均不敏感。氧分压的提高对点火时间没有影响，但使燃烧时间明显减小，而水蒸气分压的升高则显著降低点火时间，但对燃烧时间几乎没有影响。环境温度的升高会减小点火时间，但对燃烧时间的影响可忽略。

Abstract:

The ignition and combustion kinetic model for single boron particles in oxygenated environment containing O₂ and H2O was developed. The specific numerical solution method was introduced. Prediction of the models was in good agreement with experimental data. The effects of particle size，initial oxide thickness，ambient pressure，partial pressure of oxygen，partial pressure of water vapor，and ambient temperature on boron ignition and combustion were investigated by numerical calculation. The results were compared with experiment as well. The results show both the ignition and combustion time increase with increasing particle size. The combustion time is found to be in direct proportion to particle size，but this dependency changes to quadratic when the particle size exceeds 20μm. The ignition time increases significantly as the initial oxide layer increases with a growth rate of 65ms/μm. Increased ambient pressure reduces both the ignition and combustion time，whereas the sensitivity is very weak at pressure higher than 3MPa. The ignition time is independent of oxygen partial pressure but decreases with increased water vapor partial pressure. On the contrary，the combustion time is independent of water vapor partial pressure but decreases with increased oxygen partial pressure. Similar effects on the ignition and combustion time as function of ambient temperature are obtained.