正庚烷氧化基态OH基浓度时程吸收光谱诊断

To provide microscopic validation data for n-heptane models over a wide temperature range, microsecond-resolved OH concentration time-histories were measured behind reflected shock waves in the oxidation of stoichiometric n-heptane (volume fraction of 0.1%)/O₂/Ar mixtures over the temperature (T₅) range of 1 197-1 690 K at the pressures (p₅) around 150 kPa. The OH time-histories were monitored by narrow-linewidth ring dye laser absorption near 306.7 nm at the well-characterized R₁(5) transition of the OH A-X(0, 0) band. Results reveal that vacuum degree and leaking rates are the two dominant factors affecting peak value of the measured OH concentrations. Three morphologies of OH time-histories in n-heptane oxidation were observed, and the non-ideal physical boundary layer effect caused by incident shock wave shows a significant effect on OH concentration. Five commonly used mechanisms of n-heptane generally show acceptable predictions in the trend of OH time-histories at various temperatures, but are still not satisfactory in predicting both ignition delay time and OH time-histories simultaneously, and it shows that the lower the temperature, the greater the deviation between the model simulations and experimental measurements during induced ignition time. Reaction of ĊH₃+HȮ₂=CH₃Ȯ+ȮH has a great impact on the predictions in ignition delay times of n-heptane models, and further study on the kinetic parameters of this reaction is beneficial to refining the n-heptane models.