煤油裂解产物/空气与煤油/空气在宽温度范围内点火延迟的对比研究（英文）

煤油是一种理想的吸热性碳氢燃料,其热裂解在高速飞行器的热防护中起着重要作用。本工作利用加热激波管测量了煤油裂解产物/空气和煤油/空气的点火延时,点火温度657–1333 K,化学计量比1.0,点火压力1.01×10~5–10.10×10~5Pa。通过对高温点火延时数据的拟合获得了两种混合物关于点火延时间和点火条件(温度和压力)的Arrhenius型关系。测量结果显示,在高温区( 1000 K)两种混合物的点火延时很接近,并且点火延时随着温度或压力的增加而变短。但在低温区(1000 K),两种混合物的点火延迟特性却非常不同。煤油裂解产物的点火延时在此低温区域仍然随着温度的减小而增长,没有出现着火延迟的负温度效应;煤油的点火延迟在此温度区域却表现出明显的负温度效应。在830–1000 K温度区间,煤油裂解产物的点火延时快于煤油的;当温度低于830K时,煤油的点火延迟时却变得比煤油裂解产物的快很多。本实验结果与机理模拟结果的比较显示,对煤油裂解产物和煤油燃烧反应机理的完善是必要的。本研究结果对了解煤油裂解产物的点火延迟特性和发展高速飞行器再生冷却技术非常有帮助。     

Laser absorption spectroscopy for high temperature H_2O time-history measurement at 2.55 μm during oxidation of hydrogen

Concentration time-histories of H_2O were measured behind reflected shock waves during hydrogen combustion. Experiments were conducted at temperatures of 1117–1282 K, the equivalence ratios of 0.5 and 0.25, and a pressure at 2 atm using a mixture of H_2/O_2 highly diluted with argon. H_2O was monitored using tunable mid-infrared diode laser absorption at 2.55 μm(3920.09 cm~(-1)). These time-histories provide kinetic targets to test and refine reaction mechanisms for hydrogen. Comparisons were made with the predictions of four detailed kinetic mechanisms published in the last four years.Such comparisons of H_2O concentration profiles indicate that the Aramco Mech 2.0 mechanism yields the best agreement with the experimental data, while CRECK, San Diego, and HP-Mech mechanisms show significantly poor predictions.Reaction pathway analysis for hydrogen oxidation indicates that the reaction H + OH + M = H_2O + M is the key reaction for controlling the H_2O formation by hydrogen oxidation. It is inferred that the discrepancy of the conversion percentage from H to H_2O among these four mechanisms induces the difference of performance on H_2O time-history predictions. This work demonstrates the potential of time-history measurement for validation of large reaction mechanisms.