直流电场对预混CH_4/O_2/N_2火焰传播特性影响的试验研究

Effect of Direct-Current Electric Field on Flame Propagation Characteristics of Premixed CH_4/O_2/N_2 Flames

为研究直流电场及其极性对火焰传播行为的影响,利用高速摄像法和球形扩展火焰理论在定容燃烧弹上展开了正负直流电场作用下预混CH4/O2/N2火焰传播规律的试验研究。试验结果表明:对于化学计量空燃比混合气,施加电场后球形火焰面在水平方向上被拉伸,拉伸火焰传播速率、无拉伸层流燃烧速率以及马克斯坦长度均随着输入电压幅值的增大而增大,且负电场比正电场的作用更加显著。当输入电压为-5kV与5kV时,火焰传播速率相对于未加电场时分别增加了10.85%和5.66%,而层流燃烧速率则分别增加了13.13%和6.98%。因此,电场能有效促进火焰传播,改善燃烧以及提高燃烧稳定性。

In order to investigate the effects of a direct-current（DC） electric field and its polarity on flame propagation characteristics,an experiment investigation on the effects of positive and negative DC electric fields on the spherically expanding premixed CH4/O2/N2 flames was conducted at the stoichiometric fuel/air ratio and room temperature using schlieren photography.The experimental results show that when a DC electric field is applied,the flame front is stretched in the horizontal direction,and the stretched flame propagation speed,unstretched laminar burning velocity and Markstein length increase with an increase in voltage magnitude.The influence of negative electric fields on these characteristics is more effective than that of positive DC electric fields.When the input voltage of-5 kV and 5 kV is applied,the stretched flame propagation speed increases by 10.85% and 5.66%,and unstretched laminar burning velocity rises by 13.13% and 6.98%,respectively,compared with that of 0 kV.It seems that flame propagation and stability can be effectively enhanced by DC electric fields.