对无重力、相对静止热环境中碳氢燃料单液滴的蒸发燃烧过程,建立了非等温液滴蒸发-火焰面燃烧耦合模型。考虑了液滴内导热、液滴表面蒸发、火焰面化学反应以及气相区对流传热传质的瞬态耦合作用。将整个耦合系统分解为液滴、火焰面内气相区、火焰面外气相区三个相对独立的计算域,采用固定计算域法与随动坐标系,结合耦合界面条件,进行数值求解。分析了液滴蒸发燃烧过程中的传热传质特性以及环境压力的影响。结果表明,液滴蒸发与燃烧强烈耦合,过程后期的蒸发和火焰面动态特性与初期明显不同。
For the evaporation-combustion process of a single droplet of hydrocarbon fuel in a thermal surroundings without gravity and forced flow,an evaporation model of nonisothermal droplet coupled with the flame sheet model of combustion was developed.The transient interaction among the heat conduction inside droplet,the evaporation from droplet surface,the chemical reaction at flame sheet and the convective heat and mass transfer in gas phase has been taken into account.The coupled system was divided into three calculating zones,which are the droplet,the gas phase within flame sheet and the gas phase beyond flame sheet,and they are relatively independent.By employing the method of fixed calculating zone and the following coordinates combined with the coupled interface conditions,the numerical simulation was conducted.The heat and mass heat transfer as well as the effects of ambient pressure were analyzed.The results show the intensive coupling of droplet evaporation with combustion.The evaporation and the dynamic characteristics of flame sheet in the terminal stage are both quite different from those in the earlier stage.