乙烯着火延迟的激波管测量与分子碰撞理论分析

在75%和96%两个不同的稀释度下，测量了乙烯/氧气/氩气混合气的着火延迟时间，实验当量比为1，压力为1.3-3.0 atm，温度为1092-1743 K.实验结果表明，着火延迟时间的对数与温度倒数呈良好的线性关系，在两个稀释度下，着火延迟时间随着温度增加而减少.通过回归分析，得到了乙烯着火关联式.计算得乙烯着火延迟在96%稀释度时是75%稀释度的5倍.采用分子硬球碰撞模型，计算了不同稀释度下，乙烯与氧分子的碰撞次数，在96%稀释度下，乙烯与氧气分子碰撞次数为1.53×10²⁹/（s·cm³），而在75%稀释度下，该碰撞次数增加为5.99×10³⁰/（s·cm³），约为前者40倍，而着火延迟时间的差异在两条件下仅为5倍的关系，可能由于位阻因子的影响所致.

Shock Tube Measurement of Ethylene Ignition Delay Time and Molecular Collision Theory Analysis

In this study, 75% and 96% argon diluent conditions were selected to determine the ignition delay time of stoichiometric mixture of C₂H₄/O₂/Ar within a range of pressures (1.3-3.0 atm) and temperatures (1092-1743 K). Results showed a logarithmic linear relationship of the ignition delay time with the reciprocal of temperatures. Under both two diluent conditions, ignition delay time decreased with increased temperature. By multiple linear regression analysis, the ignition delay correlation was deduced. According to this correlation, the calculated ignition delay time in 96% diluent was found to be nearly five times that in 75% diluent. To explain this discrepancy, the hard-sphere collision theory was adopted, and the collision numbers of ethylene to oxygen were calculated. The total collision numbers of ethylene to oxygen were 5.99×10³⁰ s^-1cm^-3 in 75% diluent and 1.53×10²⁹ s^-1cm^-3 in 96% diluent (about 40 times that in 75% diluent). According to the discrepancy between ignition delay time and collision numbers, viz. 5 times corresponds to 40 times, the steric factor can be estimated.