激光与热丝点火对多组分液滴着火及燃烧的影响

采用挂滴方法，实验研究多组分单液滴的着火和燃烧特性，考察激光和热丝两种点火方式对液滴燃烧速率、火焰形貌及着火延迟时间的影响.实验结果表明，随着热丝点火时间增加，燃烧速率因液滴周围自然对流增强而加快.常重力下液滴火焰为包覆型火焰，火焰高度与液滴初始直径之比的最大值约为18.当t/t_b>0.4时，尚处于热丝加热阶段的火焰高度比没有热丝加热的高约5D₀，比激光关闭后的火焰高度高5~10D₀.与热丝点火相比，激光点火响应迅速，对液滴附近气体干扰小，是地面上比较理想的点火方式.固定激光脉冲时间，随着激光强度的增加，单液滴的着火延迟时间缩短. 

Effects of Laser and Hot Wire Modes on Ignition and Combustion of Single Multicomponent Droplet

The ignition and combustion characteristics of multicomponent fuel as single suspended droplet are conducted. The effects of laser and hot wire ignition on droplet burning rate, flame morphology and ignition delay time are analyzed. The experimental results show that, as the hot wire ignition time increases, the burning rate increases with the increase of natural convection around the droplet. Under ambient environment, the droplet flame is a teardrop shaped flame, and the maximum ratio between the flame height and the initial droplet diameter is about 18. When t/t_b>0.4, the flame height of the droplet when heated by the hot wire is 5D₀ higher than that in subsequent non-heating stage, and 5~10D₀ higher than that of the droplet ignited by the laser. Compared with the hot wire ignition, the laser ignition responses faster and causes less interference to the flow field near the droplet. Therefore, the laser ignition is an ideal method of the droplet combustion experiments on the ground. With a fixed laser pulse time, the ignition delay time of single droplet becomes shorter when the laser intensity increases.