基于多层氧化层结构的硼颗粒点火模型研究

为了研究相关因素对硼颗粒点火过程的影响规律,基于多层氧化层结构,改进了硼颗粒的点火模型。该模型考虑了颗粒氧化层表面物质成分的变化、表面火焰面形成的物理过程,模型计算结果与实验数据具有较高的吻合度。应用该模型研究了环境压强、颗粒直径、气相氧化剂浓度以及环境温度对硼颗粒点火过程的影响规律。结果表明,环境压力越大,颗粒点火时间越短;颗粒粒径越大,颗粒表面氧化层越厚,从而延长了颗粒的点火时间;在较大颗粒直径(5μm)下增加环境内氧气浓度有利于颗粒点火,对小颗粒直径(≤5μm)则无明显影响;水蒸气浓度越大,颗粒点火时间越短;环境温度越高,越有利于颗粒点火。

Research on Model of Ignition of Boron Particle Based on Multiple Oxide Layer Structure

In order to study the influence of the related factors on the ignition process of boron particle by using numerical calculation method, an improved ignition model of boron particle is developed under the consideration of the multilayer oxide structure. The physical process of the change of species at the surface of the oxide layer and the formation of surface flame is considered in the model. The simulation results are in good agreement with published experimental data. The influences of ambient pressure, particle diameter, kinds of oxidant and their concentration, ambient temperature on the ignition process of boron particle are studied by using the improved ignition model. The simulation results show that the ignition time is shortened at higher ambient pressure. The larger the particle diameter is, the thicker the oxide layer is, thus delaying the ignition time. The higher oxygen concentration has a good effect on the ignition of boron particle on the larger particle diameter（>5 μm）, but has little significant influence on smaller particle diameter(≤5 μm). The ignition of boron particle is promoted with water vapor available. The higher concentration of water vapor makes the ignition time reduced. The higher ambient temperature is useful for the ignition of boron particle.