垂直管道中锆粉云火焰传播速度特性及锆颗粒群燃烧模型

在粉尘云瞬态火焰实验系统上开展实验研究,揭示了垂直管道中锆金属云的火焰传播速度特性并建立了垂直管道中向上运动的锆颗粒群燃烧模型. 研究结果表明,锆颗粒的燃烧产物二氧化锆颗粒具有单斜和四方两种晶相. 管道中的锆粉云浓度高低可根据火焰锋面形状进行初始判断. 垂直管道中锆粉云的最大火焰传播速度随锆粉云浓度的增加先增大后减小,这是由于管道中富燃料燃烧缺氧和未燃颗粒吸收体系热能而造成. 锆粉云浓度为0.625 kg/m3时,管道中出现最快火焰的传播速度可达39.7 m/s. 在锆颗粒群燃烧模型中将颗粒燃烧过程分为4个阶段. 从宏观现象和微观机理上对锆粉云在垂直管道中的火焰传播过程进行了表征. 

Characteristics of Flame Propagation Speed of Zirconium Dust Cloud in Vertical Pipeline and Model of Zirconium Particles Combustion

A lot of fine suspended zirconium particles can develop to become a range of flame when zirconium dust cloud burns. Zirconium powder material was widely applied as a kind of high energy fuel. Dust cloud transient flame propagation experimental system was used to study the characteristics of flame propagation speed of zirconium metal dust cloud in a vertical pipeline, and a combustion model of zirconium particles moving upward in the pipeline was established. The results show that zirconium dioxide particles have two kinds of crystal phase-monoclinic crystal phase and tetragonal crystal phase. The zirconium dust cloud concentration is high or low which can be judged preliminarily according to the initial shape of the flame fronts. The maximum flame propagation speed of zirconium powder cloud first increase then decrease with the increasing zirconium dust cloud concentration, because the oxygen in the pipeline is not enough as result of rich fuel combustion and the heat energy are absorbed by the unburned particles. When the zirconium dust cloud concentration is 0.625 kg/m³, the fastest flame propagation speed in the pipeline is up to 39.7 m/s. In addition, a combustion model of zirconium particles moving upward in the pipeline was established, the whole combustion process was divided into four stages. The flame propagation process of zirconium dust cloud in vertical pipeline are characterized from macro phenomenon and the micro mechanism.