中文摘要：

实验研究纳米铝粉在微尺度下的点火、燃烧现象,结合纳米铝氧化理论、颗粒间烧结模型,提出纳米铝粉在微尺度下的点火、燃烧模式。在微燃烧室内常温常压静止空气流中,纳米铝粉的最低激光点火功率低于13.0 m W（功率密度为1.49×10~9W/m~2）,点火延迟时间在μs量级。当点火功率密度相同时,点火延迟时间受圆形度、等效粒径和堆积密度等综合因素影响。纳米铝粉在微尺度下的典型燃烧过程包括燃烧启动、扩散燃烧、弱火焰和淬熄。纳米铝粉被激光预热、铝核升温熔化导致核壳破裂引起异相着火,破裂过程中可能发生微爆炸。着火后,在自然对流作用下,纳米铝粉发生扩散燃烧,燃烧火焰的锋面、亮度出现振荡,燃烧处于不稳定状态。微尺度下纳米铝粉燃烧存在弱火焰形式,最终发生淬熄。

英文摘要：

The ignition and combustion mechanism of nano-aluminum powders at the micro-scale was presented based on nano- aluminum oxidation theory,interacting particle sintering model and the ignition and combustion phenomena of nano-aluminum pow- ders at the micro-scale.In a stagnation air flow of the micro-scale combustor at atmospheric temperature and pressure,the minimum laser ignition power of nano-aluminum powders is less than 13.0 mW （ power density of 1.49× 109 W/m2 ）, and the ignition delay time is in the magnitude of micro seconds order.As the laser ignition power density is the same ,the ignition delay time is influenced by the roundness, equivalent diameter and bulk density of nano-aluminum powders.The classical combustion of nano-aluminum pow- ders includes four stages,i.e. ,the startup of combustion, diffusive combustion,weak flame and extinction.The nano-aluminum pow- ders are preheated by laser, and then heterogeneously ignited as the alumina shells rupture due to the melting of the core.At the mo- ment of rupture, the micro-explosion might take place. After ignition, nano-aluminum powders combust diffusively in the naturally convective air flow.The fluctuation of the flame front and flame brightness shows instability of combustion.At the micro-scale, the dif- fusion combustion followed by the weak flame, and the flame eventually extinguishes.