An experimental and computational investigation is carried out to characterize the influence of reactants on critical conditions for extinction and for autoignition of propane and n-heptane in nonpremixed counterflow configurations. Propane or vaporized n-heptane mixed with nitrogen is transported in one stream while the other stream is made up of air mixed with nitrogen. Measurements of the oxidizer stream temperature needed for autoignition are made at fixed values of the strain rate, either with the fuel mass fraction varied at a fixed oxygen mass fraction or with the oxygen mass fraction varied at a fixed fuel mass fraction. Extinction strain rates for propane are measured as a function of the oxygen mass fraction with room-temperature feed streams and the fuel mass fraction fixed and for n-heptane as a function of the fuel mass fraction with the oxygen mass fraction and feed-stream temperatures fixed. Predictions of critical conditions for extinction and autoignition are made employing detailed kinetic mechanisms. Predictions of critical conditions for extinction are in reasonable agreement with measurements, but there are significant discrepancies for autoignition. Measurements show that increasing the mass fraction of either fuel or oxygen increases the overall reactivity thereby reducing the autoignition temperature. The kinetic models predict the increase in reactivity of the mixing layer with increasing mass fraction of fuel but predict very little change in reactivity of the mixing layer with increasing mass fraction of oxygen, thus failing to predict the influence of oxygen on autoignition. It is concluded that there may exist kinetic pathways responsible for this disagreement that are yet to be discovered, and paths that fail to explain the results are identified.

进行了实验和计算研究，以表征反应物对非预混逆流配置中丙烷和正庚烷的灭绝和自燃关键条件的影响。丙烷或汽化正丁烷与氮气混合的庚烷以一股流的形式输送，而另一股物流由与氮混合的空气组成。在固定的应变率值下进行自动点火所需的氧化剂物流温度的测量，或者燃料质量分数以固定的氧气质量分数变化，或者氧气质量分数以固定的燃料质量分数变化。丙烷的消光应变率是在室温进料流和燃料质量分数固定的情况下，根据氧气质量分数和n-庚烷是燃料质量分数的函数，氧气质量分数和进料流温度是固定的。使用详细的动力学机制对灭绝和自燃的临界条件进行了预测。预测灭绝的临界条件与测量值合理吻合，但是自燃存在显着差异。测量表明，增加燃料或氧气的质量分数会提高整体反应性，从而降低自燃温度。动力学模型预测混合层的反应性随燃料质量分数的增加而增加，但是预测混合层的反应性随氧气质量分数的增加而很少变化，因此未能预测氧气对自燃的影响。