离子电流法测量CH_4/H_2混合气燃烧火焰传播速度的实验研究

Measurement for Flame Speed of CH_4/H_2 Blends with Ionic Current Method

在定容燃烧弹上布置一对测量电极,运用离子电流法、根据燃烧火焰在接触测量电极时刻的离子电流信号值,对不同工况下CH4/空气及其掺氢混合气的平均火焰传播速度进行了计算,并与传统光学纹影法测得的火焰速度进行了对比。结果表明：对于CH4/空气混合气预混燃烧火焰,在过量空气系数分别为0.75、0.8、0.85、0.9、1、1.1时,利用离子电流法测得的火焰传播速度分别为1.714、1.935、2.195、2.250、2.045、1.538 m/s,相对纹影法误差分别为1.32%、2.09%、4.65%、3.48%、3.64%、7.06%;对于过量空气系数为0.8的CH4/H2燃料,在掺氢比为0%-80%（10%递增）的情况下,离子电流法测得的火焰传播速度相对于纹影法的误差均在5%之内。该结果为离子电流法的层流火焰传播速度测量提供了理论、实验依据,测量方法简单易行、快捷准确、可行性高。

Ionic current method was chosen to obtain the flame speed of CH4/H2 mixture over a wide range of excess air ratios and hydrogen fractions. The characteristic parameters of ionic current signal corresponding to the contact between spherical expanding flame and a pair of electrodes installed in a constant volume combustion bomb were investigated. Additionally, the flame speeds obtained with ionic current method were compared with those obtained by the traditional schlieren photography. The results show that for the CH4/air mixture at the excess air ratios of 0.75, 0.8, 0.85, 0. 9, 1.0 and 1.1, the flame propagating speeds measured with the ionic current method are 1. 714, 1. 935, 2. 195, 2. 250, 2. 045 and 1. 538 m/s, respectively, and the deviations from the speeds measured with the schlieren photography are 1.32%, 2.09%, 4.65%, 3.48%, 3.64% and 7.06%, respectively. For the CH4/H2 mixture at the excess air ratio of 0.8 and the hydrogen fraction of 0%-80% （10% increment）, all the deviations between the flame propagating speeds measured with the ionic current method and the schlieren photography are less than 5 %. This method is simple and practicable to achieve the flame speeds with higher accuracy and feasibility.