Research On Working Process And Performance Of Elliptical Nozzle Diesel Engine

In recent years,many researchers have found that elliptical injection holes have the potential to improve the quality of diesel fuel atomization and improve the quality of diesel and gas mixture.Therefore,the simulation to verify the feasibility of using elliptical nozzles to enhance the diesel oil-gas mixing process was carried out.The experiment to study the variation law of combustion process,economy and emission performance of diesel engine after applying elliptical nozzle was carried out.The optimization control strategy of diesel engine performance based on the multiple injection technology of elliptical nozzle was explored,which provides the engineering application of elliptic nozzle injection nozzle on diesel engine and the design of new combustion system using non-circular nozzle injection.Firstly,a numerical simulation model of the diesel engine oil-gas mixing process was set up to explore the influence of injection hole shape parameters on the diesel engine spray development and oil-gas mixture,and verify the feasibility of using elliptical injection holes to enhance the diesel oil-gas mixing process.The results show that after the elliptical nozzle is used,the spray cone angle of the diesel engine becomes larger,and the air entrainment effect is enhanced leading to the air entrainment volume increases.The contact area of the fuel and air and the spray development resistance increase,and the spray penetration distance is shortened.The spray penetration distance of the elliptical nozzle 1 and the elliptical nozzle hole 2 was shortened by 11% and 8.3%,respectively.The area of the high concentration area near the wall surface is reduced,the fuel spray evaporation speed is accelerated,and the fuel evaporation rate is increased.Increased spray instability leads to more complete fuel breakup and reduced mixture SMD.Therefore,the use of elliptical spray holes is beneficial to improve the uniformity of the mixed gas.The working process and performance test bench of the diesel engine was set up to carry out In-cylinder pressure collection and bench performance test.The influence law of elliptic injection hole on the combustion process and performance of diesel engine under single injection strategy was studied.The performance optimization path of elliptic nozzle diesel engine under single injection strategy was explored.The results show that after using elliptical nozzles,the premixing period and stagnation period are shortened,and the combustion duration increases.Peak incylinder combustion pressure,peak instantaneous heat release rate,and average in-cylinder temperature are all reduced.NOx emissions are significantly reduced,soot emissions increases,and fuel economy is improved.When the fuel injection timing is postponed,the NOx emission reduction rate increases first and then decreases.Finally,in order to further improve the relationship between NOx and soot emissions Trade-off and improve diesel fuel economy,pre-injection strategy was introduced.The influence of the elliptical nozzle injection nozzle on the diesel engine emissions and economic performance under the pre-injection strategy was studied.The diesel engine performance optimization control strategy based on the elliptical nozzle multiple injection technology was explored.The results show that under the pre-injection strategy,the lag period of pre-injection combustion of the diesel engine increases after the elliptical injection hole is used,and the combustion phase is closer to the main injection time,resulting in higher temperature and pressure in the cylinder during main injection,which is beneficial to evaporation and mixing of main injection fuel.Compared with the single injection strategy,while the NOx emission reduction of the elliptical nozzle diesel engine is reduced,the increase in smoke emission has been greatly improved,and the effective fuel efficiency was constant.Reducing the pre-injection interval increases the NOx emission reduction and soot emission,which is more obvious under small load conditions.Increasing the pre-injection amount leads to the NOx emission and effective fuel consumption rate decreasing.The increase in emissions decreases first and then increases.By adjusting fuel injection parameters,the performance optimization control strategy of the elliptical nozzle diesel engine was determined.Compared with the original engine,under 25%,50% and 75% load conditions,NOx emissions were reduced by 18.18%,19.67%,and 33.68%,smoke emissions were reduced by 7.29%,19%,and 16.99% respectively,fuel consumption rate was decreased by 1.1%,0.8% and 0.6% respectively.