40Hz低频交流电场对甲烷/空气稀燃火焰的影响

Effects of low-frequency alternating electric fields at frequency of 40 Hz on lean methane/air flames

为研究不同电压有效值的低频交流电场对预混稀燃火焰的影响,在40 Hz交流电压作用下,对常温、常压下定容燃烧弹中过量空气系数λ为1.2,1.4和1.6时的甲烷/空气火焰的传播特性和燃烧压力进行研究。研究结果表明:混合气越稀,火焰在电场中传播的时间越长,电场对火焰的作用效果越明显;40 Hz交流电压作用下,火焰均在水平方向被拉伸,且拉伸的程度与电压有效值正相关,平均火焰传播速度和燃烧压力随着电压有效值的增大而增大;与未加载电压相比,当过量空气系数λ=1.6,电压有效值U为1,2,3,4和5 k V时,平均火焰传播速度分别提高17.24%,32.76%,46.55%,55.17%和74.14%,相对燃烧压力增大率的最大值分别为0.19,0.24,0.36,0.49和0.65。

An experiment was conducted under a lean combustion conduction to investigate the influences of low-frequency alternating electric fields of different voltage virtual values on the flame propagation and combustion characteristics of premixed CH4/air mixtures at the excess air ratio（X） of 1.2, 1.4 and 1.6, room temperature and atmospheric pressure. The results show that the effect of electric field on the flame is greater when the mixture is diluted. The flame is stretched in the horizontal when low-frequency altemating electric field at the frequency of 40 Hz is applied in the electrodes and the flame is stretched more severely when the voltage virtual value increases. Both the average flame propagation speed and the combustion pressure increase as the voltage virtual value increases. Compared with those without the applied voltage, when the excess air ratio is 1.6, the average flame propagation speeds at the voltage virtual value of 1, 2, 3, 4 and 5 kV increase by 17.24%, 32.76%, 46.55%, 55.17% and 74.14%; the maxima of the increasing rate of relative combustion pressure are 0.19, 0.24, 0.36, 0.49 and 0.65, respectively.