Ignition Delay Characteristics Study Of Kerosene And Contaminated Kerosene In Shock Tube

The study of chemical kinetic mechanism about kerosene combustion has become a hot issue in the filed of supersonic combustion in recent years. Measuring the ignition delay time of kerosene under different temperature and pressure conditions can serve as the important basis for validation of combustion reaction mechanism and simplification of the chemical kinetic model. Therefore, the study of ignition delay of a fuel could provide the important basic data for the design and optimization of the combustion chamber of the scramjet engine.Shock tube is the main experimental facility for the measurement of the ignition delay time for hydrocarbon fuels. A wide range of temperature and pressure can be extended by adjusting the speed of the incident shock wave. This thesis will study the ignition delay characteristics of the China No. 3 aviation kerosene at relatively high pressures and lower argon dilution. Thereafter, the contamination of water and carbon dioxide on kerosene ignition characteristics has been examined.First of all, a new experimental assembly consisted of shock tube, intake system,gas distribution system, vacuum system, pressure measurement system and spectroscopic measurement system was constructed, and the shock tube status debugging was completed. Meanwhile, the critical rupture pressures of different types of aluminum diaphragm were determined by shock tube experiments, providing a basis for the choice of the diaphragm in the next shock tube experiments.Secondly, the ignition delay characteristics of the China NO.3 aviation kerosene/ O2/Ar mixture were measured with the indication by the steepest rise of the characteristic emission from OH radical at 306.5nm. The oxygen content of the test mixture was 19.88 %( vol) and the argon was about 80%. The experimental conditions cover pressures at 5.5atm﹑11atm and 22atm, equivalence ratio of 0.5﹑1.0 and 1.5, and temperature range from 820 to 1580K, respectively. The impact of the pressure and equivalence ratio on ignition delay characteristics of China NO.3 aviation kerosene was investigated. The dependence relation of the ignition delay time of China NO.3 aviation kerosene with temperature, pressure, stoichiometric ratio, fuel concentration, oxidant concentration and other parameters was obtained by least squares fitting as follows: where the ignition delay time is in seconds, kerosene and O2 concentrations in mol/cm3, total pressure P in atm,Φis the stoichiometric ratio, and the ignition activation energy is in J / mol.Finally, on the basis of the kerosene ignition delay time data, the impact of the contaminants of water and carbon dioxide on the kerosene ignition delay was examined. The ignition delay time of kerosene without contamination was firstly measured at equivalence ratio of 1.0, pressure of 3atm, and over the temperature range from 810 to 1350K. Then the variation of ignition delay of test mixture was measured, with added contaminant water 10% and 20% (vol) and carbon dioxide 10% (vol), respectively. The results showed that carbon dioxide has no effect on the ignition delay time of kerosene. When adding water in the kerosene mixture, there exists a critical temperature of 960K. Above this critical temperature, the water has no effect on the ignition delay time of kerosene, while below the critical temperature water has an enhance effect on the kerosene ignition, as a result of shortening the kerosene ignition delay time. The enhance effect is more significant over the lower temperature range and with increasing water content in the kerosene mixture.