Simulation And Optimization Research Of4D83Diesel Engine Combustion System

Diesel Engine gained more and more market for its good performance on economy,power and reliability. European experience shows that diesel engine for cars have a largermarket space as well. However diesel engine is used for commercial vehicles more than carsin the domestic. Therefore the development and research on diesel engine for cars hasimportant practical significance and practical value in the domestic. In this paper thecombustion system has been further developed and optimized of the4D83diesel engine. Atthe same time different injection strategies and injection parameters were studied toinvestigate the further improvement room for emissions and power.In this paper we build the4D83diesel engine’s combustion chamber geometry modelwith PROE software. Use the AVL FIRE software to mesh the geometry model and simulatethe combustion process. Build4D83prototype test bench and do some performance test. Theexperimental data were compared to the simulation results to ensure the accuracy of thegeometry model and the calculation model.Use AVL FIRE to simulate four different combustion chamber geometry models toinvestigate its effects on the performance of the engine. The study shows that theω-combustion chamber necking diameter proper decrease and the depth of the pit increase,we can ensure that the engine’s power and economy unchanged, while effectively reducingthe amount of NOx and Soot combustion generation. The optimization study on the injectorparameter show that ensuring the prototype power and economy unchanged with decreasethe height of injector nozzle protruding the bottom of the cylinder head and increase theangle of the injector nozzle holes, through the proper diesel distribution and cooperate withair movement can effectively control the burning rate, increased post-combustion to increasethe post-oxidation of soot while effectively decrease the formation of the NOx. BreakingNOx and Soot generated contradictory relationship between the amount of the shift. Such that the final Soot and NOx generation amount can simultaneously reduced.The study of three different strategy under1800rpm,full load condition shows thatcompared with the use of single main injection strategy, the use of pilot injection caneffectively reduce NOx emissions, and after injection strategy can effectively reduce Sootformation. The study of the timing and fuel mass of the pilot injection shows that when theinterval of the pilot injection and main injection changes from23°CA to15°CA, NOx andSoot formation both increase. When the fuel mass injected into the cylinder from one holechanges from0.075mg to0.475mg, the engine power performance decreased slightly, NOxgeneration amount is gradually reduced, Soot generation amount decrease after the firstincrease; Research on after injection parameters shows that when the interval between maininjection and after injection changes from6°CA to14°CA, the power and emissionperformance of the engine are essentially the same. When the fuel mass injected into thecylinder during the after injection from one hole changes from0.1mg to0.5mg, enginepower performance decreased slightly, NOx formation gradually decreased and the Sootgeneration amount decrease after the first increase. Comprehensive consideration of all thefactors, when using the pilot injection strategy, it is suggest to chose largest interval and themost fuel mass for the pilot injection. The interval between main injection and after injectionhas little impact on the power and emission performance of the engine, increasing the fuelmass of the after injection can reduce engine emissions, but to sacrifice some engine power.