Study of n-Butylcyclohexane/Air Ignition over a Broad Range of Temperatures in Shock Tube

Measurements of ignition delay times for n-butylcyclohexane/air were performed over temperatures of 707–1458 K, pressures of 2.0, 5.0, and 15.0 atm, and equivalence ratios of 0.5, 1.0, and 2.0 in a heated shock tube. High temperature (>1000 K) results reveal that increasing of temperature or pressure results in a monotonous decreasing of ignition delay time at fixed equivalence ratios, effects of equivalence ratio on ignition delay are different at different pressures, and ignition delay times of fuel-lean mixture are the most sensitive to temperature. At low temperatures (n-butylcyclohexane were compared to those of cyclohexane, methylcyclohexane, and ethylcyclohexane, and also to those of C10 fuels of n-decane and n-butylbenzene. Mechanism predictions agree well with present measured data qualitatively, and are longer than the data at most conditions. The key reactions influencing ignition delay and reaction pathways during ignition process of n-butylcyclohexane/air are different at high and low temperatures. The results obtained in this work are valuable for understanding characteristics of n-butylcyclohexane ignition and provide new experimental data for refining kinetic mechanism of n-butylcyclohexane.本研究在加热激波管中开展了正丁基环己烷/空气混合气的着火延迟时间测量实验，实验覆盖温度区间707~1458 K、压力2.0、5.0及15.0 atm，当量比0.5、1.0及2.0。高温（>1000 K）实验结果表明：在固定当量比条件下，温度或压力升高会使着火延迟时间单调降低；当量比对着火延迟的影响随压力变化存在差异；贫燃混合物的着火延迟时间对温度变化最为敏感。在低温工况下，将正丁基环己烷的着火延迟时间与环己烷、甲基环己烷、乙基环己烷，以及C10燃料正癸烷、正丁基苯的着火延迟时间进行了对比。动力学机理的预测结果与本次实验测量数据定性吻合良好，但在多数工况下预测值高于实验测得数据。影响正丁基环己烷/空气着火延迟与着火过程反应路径的关键反应，在高低温区间存在显著差异。本研究所得结果有助于深入理解正丁基环己烷的着火特性，并为正丁基环己烷的动力学机理优化提供了全新的实验数据支撑。