| Energy scarcity and environmental pollution are two important factors that restrict economic development.The automobile industry is a pillar industry of a country's national economy.Energy saving and environmental protection are the only way for the development of automobile industry in the future.As a substitute fuel,methanol has the advantages of mature extraction technology,low production cost,little environmental pollution,and can reduce the dependence on petroleum resources.It has been widely applied to the automotive industry.At present,the application of methanol fuel in the engine is mainly cold starting,and the performance of atomization has a great influence on the cold start of methanol fuel.As the key part of fuel injection system,nozzle structure parameters directly affect the flow characteristics of methanol fuel in the nozzle,which further affects the atomization quality of methanol,and determines the power,economy and emission of methanol vehicle.Therefore,it is important for us to study the change of nozzle jetting hole structure parameters for methanol fuel in the nozzle flow field and the atomization characteristics of the external field.Taking atomization source nozzle as the research object,the influence of nozzle diameter,inlet radius and nozzle taper on the atomization characteristics of methanol fuel is studied.According to the actual structure of the TS16949 injector Wuxi oil pump factory to provide the use of SolidWorks to establish a three-dimensional geometric model of the nozzle,the mesh model into ICEM CFD software built,then the grid file into FLUENT software to set the boundary conditions and the two-phase mixture model parameters,calculation simulation data of methanol flow in the nozzle internal pressure the strength,velocity and turbulent kinetic energy.Secondly,establish geometric model of atomization field,divide the grid will be coupled to the atomizing nozzle model of methanol in the fuel injection nozzle inside,external jet process numerical simulation,obtained different diameter of nozzle hole,radius of curvature and the orifice entrance taper of methanol spray penetration,spray cone angle and SMD,the main conclusions are as follows:In the nozzle,the flow velocity of the outlet decreases and the kinetic energy intensity decreases along the axis of the nozzle hole.The larger the diameter is,the larger the concentration range of turbulent kinetic energy is.The radius of curvature of the nozzle entrance is greater,methanol fuel through the nozzle entrance become more smooth,negative pressure zone formed by the aggregation of the entrance hole decreases,the nozzle exit velocity increases gradually,the turbulent kinetic energy decreased rapidly,r= 0.2mm,at the entrance there is no higher turbulent kinetic energy;The greater the taper of the jet hole is,the velocity of the outlet of the nozzle is quicker and the turbulent kinetic energy at the entrance is reduced.Outside the nozzle,the larger nozzle diameter,the distance gradually decreased through the methanol fuel,the spray cone angle increases,when the nozzle diameter increases from 0.1mm to 0.3mm,the penetration decreases by 20%,increase the spray cone angle of 15 degrees,the average diameter of oil droplet particles greatly,reduces the atomization performance of methanol;Increasing the nozzle entrance radius of curvature,through the methanol fuel distance increases gradually,and the spray cone angle is also increasing trend,the orifice radius increased from 0.01 mm to 0.2mm,the penetration increased by 14.2%,increase the spray cone angle of 8 degrees,but the methanol injection rate increased significantly,SMD decreased and increased the atomization performance of methanol;With the increase of spray hole taper of K coefficient,methanol fuel spray penetration increases gradually with the increase of spray,the spray cone angle of taper hole of K decreased,the fuel injection rate in K=3 when compared to K=1 increased by nearly 36%,the role of strong air particles and the surrounding high speed,rapid breakdown of improved particle refinement.The nozzle structure improve quality of fuel atomization.Finally,through the abrasive flow process,the spray nozzle of the nozzle is processed,and the methanol atomization test platform is set up.The atomization effect of different orifice diameter,inlet radius of curvature and taper of nozzle hole is detected through atomization test.The experiment is compared with the simulation results error is about 10%-15%.The theoretical simulation is in accord with the actual test. |
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