相对静止气氛下硼颗粒着火过程

Study of ignition process of boron particles in relatively static atmosphere

针对相对静止气氛下单颗粒硼的着火过程展开了系统研究,考虑硼颗粒周围径向气相流动以及硼颗粒与周围环境间的传热和传质过程,建立了一维硼颗粒着火模型。分析了硼颗粒在实现着火和未能实现着火两种典型情形下的颗粒相、气相组分参数以及颗粒外表面上Stefan流的变化规律,并对其成因展开了分析。研究表明,在实现着火和未能实现着火两种典型情形下,硼颗粒外表面的Stefan流都会经历先由周围空间流向颗粒表面,而后变为由颗粒表面流向周围空间的过程;考虑颗粒外表面处气相Stefan流作用后,硼颗粒的着火延迟时间减少,且压力越大,影响越大。

The ignition process of boron particles in relatively static atmosphere was studied systemically. In view of the gas flow around the boron particle,the heat and mass transfer process between the boron particle and the surroundings,a one dimensional ignition model of boron particles was proposed. The changing regularities of important parameters of the gas and the particle in the two typical cases,namely,the successful ignition case and the degenerate ignition case were studied. And the mechanisms for them were analyzed in detail. The result shows that Stefan flow in both typical cases will undergo changing flow direction. Stefan flow undergoes flowing to the particle surface from the gas,and then it flows to the gas from the particle surface. Study of ignition process of boron particles in the paper shows that ignition time decrease with consideration of Stefan flow at the particle surface. And the effect increases with the ambient pressure.