高温电离气体中微细颗粒的加热

HEATING OF SMALL PARICLES IN A HIGHTEMPERATURE PARTIALLY-IONIZED GAS

本文分析表明，自由分子流区高温电离气体中颗粒的团相加热、熔化、液相加热与强烈蒸发等加热阶段所需的时间，均正比于颗粒半径，其中蒸发阶段需时最长．颗粒表面温度高于约４０００Ｋ时，热电子发射开始显著影响颗粒的加热速率，辐射则在低得多的温度下（如２０００Ｋ）开始影响颗粒的加热．

Analytical results are presented concerning the unsteady heating of metallic particles immersed in a high-temperature partially-ionized gas for the extreme case of free-molecule regime. The results show that all the time periods required for the completion of solid-phase heating, melting, liquid-phase heating and evaporation are directly proportional to the particle radius. Among the four heating steps, evaporation is by far the slowest. Thermionic emission exerts significant effect on the heating rate of particle only as the surface temperature of particle is higher than about 4000 K, while radiation heat loss from the particle assumes its influence at much lower surface temperatures (e.g. 2000 K).