Study On Ignition Characteristics Of Coal-based Jet Fuel And RP-3 Jet Fuel And Their Blends

Jet fuel from direct coal liquefaction（DCL）is an important substitute for aviation kerosene,which shoulders the dual mission of energy security and environmental protection.The investigation of ignition characteristics of DCL at different temperatures,pressures and equivalent ratios can lay the foundation and provide basis for the airworthiness certification and commercial application of DCL fuel,and also provide important basic experimental data for the establishment and simplification of DCL fuel combustion reaction kinetics mechanism.Shock tube is the major laboratory equipment for studying the ignition and combustion characteristics of fuels.It can make one-dimensional homogeneous medium non-isentropic adiabatic compression by the incident and reflected shock,which can get a wide range of temperature and pressure by adjusting the initial pressure shock wave velocity and the experimental area gas.Combining the experimental research and numerical simulation,the ignition characteristics of DCL fuel,China RP-3 and their 50/50 blends are investigated.The main research contents and conclusions are as follows:（1）The ignition delay characteristics of DCL,RP-3 and 50/50 blends under"air"ignition conditions at pressures of 2.0 bar and 10.0 bar,temperatures ranging from 920 to1690 K,and equivalent ratios of 0.5,1.0 and 2.0 were investigated.When the equivalent ratio and pressure are determined,the ignition delay of the three fuels decreases with the increase of temperature.When the equivalent ratio is constant,the ignition delay decreases with the increase of pressure.At low pressure（2.0 bar）,the ignition delay increases with the increase of equivalent ratio.Under high pressure（10.0 bar）,the ignition delay decreases and increases with the increase of equivalent ratio.Under the same working conditions,the ignition delay time of the three fuels has minor different.（2）Based on the physical properties and chemical composition of DCL and its blends with RP-3,three component and four component substitution models based on their components were established respectively.A detailed kinetic mechanism was established preliminarily for the three fuels,including 793 species and 4358 elementary reactions.The ignition characteristics of the three fuels were predicted by Chemkin Pro software using this mechanism,and the prediction results showed that the simulation results were in good agreement with the experimental results.（3）The elementary reaction sensitivity of three kinds of fuel ignition process was analyzed respectively by the new mechanism.The results show that the key reactions that affect the ignition characteristics are very different.Sensitivity analysis of RP-3 showed that H+O₂<=>O+OH had the greatest promoting effect on ignition,and HO₂+OH<=>H₂O+O₂had the greatest inhibiting effect on ignition,which is consistent with existing literature.The key reactions affecting DCL and its mixed fuel with RP-3 are basically the same,but different from RP-3.The reaction with the greatest promoting effect on ignition is CH₃+HO₂<=>CH₃O+OH,and the reaction with the greatest inhibiting effect on ignition is HO2+HO2<=>O₂+H₂O₂.In addition,DECALIN+HO₂<=>RDECALIN+H₂O₂has a significant effect on the ignition process of DCL and blend fuels.