Visualization Study On Spray And Combustion Characteristics Of Diesel Blending With RP3 Aviation Kerosene

The universal single fuel has been paid more and more attention by the countries all over the world,due to its unique strategic significance.Reducing the types of military power fuel support is helpful to reduce the burden of logistics support and accelerate the response speed of fuel supply.However,the different application fields and functions of various power plants call for different demands on fuel properties,which posed a huge challenge to the search for universal fuel.Aviation kerosene RP-3,as a major branch of kerosene,not only has the physical and chemical properties between gasoline and diesel oil,but also has the properties very close to the U.S.universal fuel JP-8,gradually becoming a hot spot in the process of oil unification.Using constant volume combustion bomb with different optical diagnostic methods,first studied the spray and combustion characteristics of aviation heavy oil K50,which is mixed by kerosene and diesel with a volume ratio 1:1,under different environmental factors.The results show that,with the increase of the injection pressure,contribute to the atomization and evaporation of K50,the ignition delay becomes shorter,it is helpful to reduce the formation of soot.With the increase of ambient density,spray penetration faces greater resistance,the overall spray is limited in a smaller range,but the spray entrains more air,leads to a quicker combustion process,the combustion reaction is more complete.The change of ambient temperature has a little influence on the spray structure,but it will advance the ignition timing,and the ignition position is closer to the thick mixing area,soot radiation intensity increased significantly during the combustion process.Decreasing of the oxygen content can significantly prolong ignition delay,although the formation of soot in combustion process is reduced,the soot formation area is still wide.After that this paper focuses on the contrast of the spray and combustion characteristics of diesel(K0),aviation heavy oil(K50),kerosene(K100)under a base injection condition,try to find out the effect of mixing ratio on combustion of aviation heavy oil.The results show that,the higher proportion of kerosene in fuel,the smaller viscosity,surface tension and cetane number of fuel,and the fuel spray is more easily affected by the turbulence of the ambient gas,the atomization and evaporation are better.Although the cetane value decreases have a certain hysteresis effect on the ignition performance of fuel,thanks to the better evaporation,the ignition timing is still slightly advanced.And due to the combustion process began at the place equivalence ratio is smaller and the mixture is more homogeneous after blending with kerosene,the ignition position is far away from the nozzle.Also,while the carbon chain of kerosene is shorter and the higher blending ratio of kerosene bring to better atomizing effect,the average brightness of the flame and the soot density of kerosene is the lowest.