十氢萘/空气混合物高温着火延迟的激波管测量

在激波管上进行了气相十氢萘/空气混合物的着火延迟测量, 着火温度为950-1395 K, 着火压力为1.82×10⁵-16.56×10⁵ Pa, 化学计量比分别为0.5、1.0 和2.0. 在侧窗处利用反射激波压力和CH^*发射光来测出着火延迟时间. 系统研究了着火温度、着火压力和化学计量比对十氢萘着火延迟时间的影响. 实验结果显示着火温度和着火压力的升高均会缩短着火延迟时间. 首次在相对高和低压的条件下观察到了化学计量比对十氢萘着火延迟的影响是完全相反的. 当压力为15.15×10⁵ Pa时, 富油混合物呈现出最短的着火延迟时间, 而贫油混合物的着火延迟时间却是最长的. 相反, 当压力为2.02×10⁵ Pa时, 富油混合物的着火延迟时间最长. 着火延迟数据与已有的动力学机理的预测值进行对比, 结果显示机理在所有的实验条件下均很好地预测了实验着火延时趋势. 为了探明化学计量比对着火延迟时间影响的本质, 对高、低压条件下的着火延时进行了敏感度分析.结果显示, 压力为2.02×10⁵ Pa时, 控制着火延迟的关键反应为H+O₂=OH+O, 而涉及十氢萘及其相应自由基的反应在15.15×10⁵ Pa时对着火延迟起主要作用.

Shock Tube Ignition Delay Measurements of Decalin/Air Mixtures at High Temperatures

Ignition delay measurements of gas-phase decalin/air mixtures were performed in a shock tube at temperatures of 950-1395 K, pressures of 1.82×10⁵ to 6.56×10⁵ Pa, and equivalence ratios of 0.5, 1.0, and 2.0. The ignition delay time was determined using the reflected shock wave pressure and CH^* emission monitored at the sidewall. The effects of temperature, pressure, and equivalence ratio on the ignition delay time of decalin were investigated systematically. The results show that increasing the temperature or pressure decreases the ignition delay time. Opposite ignition delay dependences on the equivalence ratio were observed for decalin/air at high and low pressures, for the first time. At 15.15×10⁵ Pa, the fuel-rich mixture showed the shortest ignition delay time, and the fuel-lean mixture gave the longest one. However, at 2.02×10⁵ Pa, the fuelrich mixture had the longest ignition delay time. Comparisons of the experimental data with predictions based on the available kinetic mechanism were made; the trends in the experimental data were in good agreement with the predictions under all conditions studied. A sensitivity analysis was performed to obtain insights into the effects of the equivalence ratio on the ignition delay time at low and high pressures. The results show that ignition is mainly controlled by the reaction H+O₂=OH+O at 2.02×10⁵ Pa. However, the reactions involving decalin and its corresponding radicals play important roles at 15.15×10⁵ Pa.