微尺度条件下反复熄燃火焰特性的实验研究

Experimental study on characteristics of flames with repetitive extinction and ignition in micro combustor

在可视化微尺度燃烧实验台上进行甲烷和氧气的燃烧试验,利用高速数码照相机捕捉到了火焰面在微通道内的传播过程,测试分析了不同进气流量下反复熄燃火焰的可燃极限、火焰传播速度和火焰间隔时间,获得了反复熄燃火焰(flames with repetitive extinction and ignition,FREI)的燃烧特性。结果表明:随着甲烷进气流速的增加,可以形成FREI火焰的氧气进气流速范围也在扩大;在甲烷进气流速一定的情况下,随着氧气进气流速的增加,火焰的传播速度也逐渐增加,并且火焰重复点燃的间隔时间呈现先变大后逐渐变小的规律,即火焰重复点燃的频率先变慢后又逐渐变快直至火焰熄灭。

Micro-scale visualization experiment system and high speed digital camera were used to capture the flame propagation process in a micro parallel combustor.Tests and analysis were conducted for the flammability limits,the flame propagation speed and the interval time of the flame at different inlet feed flow rates.The characteristics of flames with repetitive extinction and ignition were obtained.It is found that the flammability limit extends with an increase in CH4 inlet rate.Flame propagation speed increases with the increasing oxygen flow rate,and the interval time of the flame shows a trend of first increasing and then decreasing,which demonstrates the frequency of the extinction and ignition turns slow and then becomes faster beyond the flammability.