STUDIES ON THE AUTOIGNITION CHARACTERISTICS OF RP-3 AVIATION KEROSENE

In a shock tube preheated at a constant temperature of 135℃, the ignition delay characteristics of RP-3 aviation kerosene were studied behind reflected shock waves by monitoring the steepest rise of the characteristic emission of OH radical at 306.5nm. Experimental conditions covered a wider temperature range of 800～1450K, at pressures of 0.05, 0.1 and 0.2MPa, equivalence ratios of 0.5, 1 and 1.5, and oxygen concentration of 20% (mol). Under low-pressure conditions, the experimental results of ignition delay time were correlated with the temperature, pressure, stoichiometry, and the concentrations of kerosene and oxygen. The comparison between current data and the previous high-pressure results shows that a critical temperature exists about the effect of equivalence ratio on the ignition behavior of RP-3 kerosene. For the higher temperature range above the critical temperature, ignition delay time increases with increasing equivalence ratio, but decreases with increasing equivalence ratio for the lower temperature range below the critical temperature. This critical temperature also rises with decreasing the pressure. Meanwhile, the ignition process of kerosene was simulated by using three kinds of kerosene combustion kinetic models, and the comparison was made between the experimental and calculated results. The results show good agreement between experimental data and the prediction based on the model of Honnet et al. at high pressure of 2.2MPa, but some differences at lower pressures. The sensitivity analyses for different pressures indicate that the three-body reaction (H+O₂+M=HO₂+M) shows a slight inhibitory effect on kerosene ignition at high pressures, but a promoting effect at low pressures.