Optimization Of Fuel Injection System Parameters On 186FA Direct Injection Diesel Engine Based On Emission Characteristics

In the face of increasingly serious energy problems and strict emission regulations,energy saving and emission reduction technology has become an important issue in the energy industry research.Especially in the internal combustion engine industry,higher requirements are imposed on engine's combustion characteristics and emission characteristics.This article aim at a non-road direct injection diesel engine model186FA,by the means of simulation calculation and experimental verification to study the influence of injection system's several main parameters,including nozzle hole number,spray angle,injection timing,and nozzle hole layout,on the combustion characteristics and emission characteristics of the diesel engine.Use the method of orthogonal experimental,the injection system parameters of the diesel engine are optimized,and obtained the parameter combination which can achieve the best emission performance.In order to further reduce the NO_X and soot emissions of diesel engine,and meet the stricter emission regulations.The main contents and conclusions are as follows:?1?The one-dimensional simulation model of 186FA diesel engine working process is established by GT-POWER software.The in-cylinder pressure of the simulation calculation are compared with the experimental results,the reliability of one-dimensional simulation model is verified,and the initial conditions and boundary conditions are obtained for the three-dimensional simulation calculation.?2?The three-dimensional simulation model of 186FA diesel engine working process is established by CONVERGE software.And the gird independence analysis is carried out on the simulation model,the results show that the calculation of the simulation model with gird size of 4mm is similar to the simulation model with smaller grid size.At the same time,sensitivity analysis of physical model used in 3D simulation is carried out,the results show that the RNG k-?RANS turbulence model and the KH-RT spray breakup model have little influence on the ignition delay angle,which can truly reflect the physical characteristics of the in-cylinder turbulence and spray breakup on the diesel engine.?3?The three dimensional simulation of the original model with the nozzle hole number of 4,the spray angle of 75 degrees,the injection timing of-7 degrees crank angle and the nozzle hole layout of single layer nozzle hole layout are carried out.The simulation in-cylinder pressure is compared with the experimental in-cylinder pressure,the peak value of the simulation calculation is 8.014MPa and the peak value of the experimental test is 7.082MPa,the relative error is 2.7%,which is less than the experimental allowable error 5%.The accuracy of the three-dimensional model is verified.?4?The simulation calculation of diesel engine working process is carried out on different nozzle hole number,different spray angle,different injection timing and different nozzle hole layout,and the influence of each parameters on diesel engine performance are obtained.The results show that the nozzle hole number mainly affects the penetration distance and atomization of diesel spray,the spray angle mainly determines the distribution of diesel spray in the combustion chamber,and the nozzle hole layout affects the distribution range of diesel in the combustion chamber;The nozzle hole number of 6,the spray angle of 75 degree,the injection timing of-7 degree crank angle and the nozzle hole layout of double layer nozzle hole layout are the most ideal scheme for each single factor.?5?An orthogonal experimental table with four factors and three levels L₉?3⁴?is established and tested,the four injection system parameters include nozzle hole number,spray angle,injection timing and nozzle hole layout,and the range analysis of the experimental results are carried out.The best combination of factor and level of NO_X and soot emission characteristics are A₂B₂C₂D₁ and A₂B₁C₃D₁,respectively.Considering the Limits and Measurement Methods for Exhaust Pollutants from Diesel Engines of Non-road mobile machinery?CHINA III,IV?of the two emissions limits,the combination of factor and level A₂B₁C₃D₁ is the most ideal experiment plan for this orthogonal experiment.That is,the nozzle hole number of 6,the spray angle of 65degree,the injection timing of-9 degree crank angle and the nozzle hole layout of single layer nozzle hole layout scheme.The three-dimensional simulation of engine working process under the scheme is carried out and the NO_X emission quality is0.2376mg and the soot emission quality is 0.1329mg.Compared with the original model,the emission quality of NO_X and soot decreased by 2.74%and 10.2%,respectively.