Research On The Combustion Characteristics Of Biofuel Used In Small Engine

Recently,with the rapid development of economy,various countries has significant dependence on oil resources.Excessive oil consumption not only caused the energy crisis,also produced a certain threat to the environment.At the same time,biofuels are developing around the world,and the government is actively encouraging the use of biofuels and providing subsidies.For aviation industry,the traditional jet fuel is one of the biggest emission sources,the application of biofuel in aviation industry can not only release the pressure of jet fuel,but also can reduce emissions(CO?NO_x).Therefore,the study of the combustion characteristics of bio-fuels in aviation engines is of great importance to the large-scale promotion of bio-fuels in aviation.Bioethanol is selected as the fuel to study the combustion characteristic of DGEN380 combustion chamber(the smallest turbofan engine in the world),including spray characteristics,ignition characteristics and combustion chamber characteristics and economical efficiency,and the result has a guiding significance to practical application in aviation field.Numerical simulation is selected as the mainly research method,and the total process includes three softwares:UG,ICEM and FLUENT.Firstly,UG is used to model the DGEN380 engine,then the combustion chamber meshes is divided by ICEM,and finally the simulation study is conducted using FLUENT.The physical parameters used in the simulation are taken from the virtual simulation platform in the laboratory,the selected models mainly include:RKE turbulence model,P1 radiation model,non-premixed PDF model and DPM model(discrete phase model).The simulation results show that:compared with jet fuel,the penetrating length of bioethanol is longer,the spray cone angle is smaller and the diameter of droplet is larger;bioethanol fuel has a longer lag period;when the fuel is burned,the reflux area will appear in the rear of the cyclone,and the speed will remain unchanged.The length of the reflux region will gradually decrease as the engine load increases;the produced CO is mainly concentrated in the reflux region,and the concentration ofNO_x increases as the temperature of the combustion chamber increases;the NOx emissions of bioethanol are an order of magnitude less than that of biodiesel and jet fuel;under the same fuel flow,the thrust of bioethanol is reduced by 1.6%and 4.3%,respectively,compared with biodiesel and jet fuel.The thrust price of bioethanol is 21.2%and 36.3%lower than that of biodiesel and jet fuel.