负直流及低频交流电场对预混火焰影响的实验研究

Experimental Research on the Effects of Negative DC Electric Field and Low-Frequency AC Electric Field on Premixed Flame

为了比较直流及低频交流电压的助燃效果,在常温常压下,对定容燃烧弹内的网状电极分别加载负直流和低频交流电压,研究了两种电压对甲烷/空气预混火焰的火焰形状、火焰传播速率和燃烧压力的影响。结果表明:负直流和低频交流电压对平均火焰传播速率和燃烧压力均有一定的促进作用,且低频交流电压的助燃效果要强于负直流电压,随着低频交流电频率的降低,对火焰的促进作用增大。当过量空气系数为1.6时,与未加载电压相比,负直流电场(电压为-5kV)和低频交流电场(频率为40、60、80、100Hz,电压有效值为5kV)作用下的平均火焰传播速率分别提高37.93%、72.41%、55.17%、48.28%和39.66%,相对燃烧压力增大量的最大值分别为0.23、0.65、0.58、0.48和0.28。

An experiment was conducted on a constant-volume combustion bomb at normal temperature and atmospheric pressure to investigate the effects of negative DC electric field and low-frequency AC electric field formed by the mesh electrodes on the flame shape,propagation speed and combustion pressure of premixed CH4/air mixtures.The results show that both the negative DC electric field and the low-frequency AC electric field can increase the average flame propagation speed and the combustion pressure and low-frequency AC electric field performs better than the negative DC electric field.When the frequency of low-frequency AC is decreased,the promoting effect is increased.When the excess air ratio is 1.6,compared with the case without the voltage applied,the average flame propagation speeds of negative DC electric field at-5kV and low-frequency AC electric fields at the frequencies 40,60,80 and 100 Hz and when the effective voltage is 5kV,will have an increase of 37.93%,72.41%,55.17%,48.28% and39.66%,respectively;and the maximum increasing rates of the relative combustion pressure are0.23,0.65,0.58,0.48 and 0.28,respectively.