Study Of The Simulation On The Combustion Process Of High Power Density Diesel Engine

With the increasing environmental pollution and the depletion of the oil resources, aswell as increasingly stringent the requirements of emissions, making it to the engine power,economy and emissions and other aspects has put forward higher requirements, thus,the theengine which has the advantages of light and high power density has been widely used.thekey to solve the above problems is that comprehensive improvement of the spray combustionprocess which react in the combustion chamber. Injection timing refers to the crank angle thatthe piston reaches top dead center from the compression at the beginning of the injector toinjection into the cylinder, is a very important parameter of the diesel engine, which directlyimpact on the quality of fuel atomization, thereby affecting the mixture formation and thecombustion processes in the cylinder. Therefore, the study of injection timing optimization ofhigh power density diesel engine combustion performance which has the importantsignificance.The dissertation discussed the model the numerical simulation and the calculationmethods about the combustion process of the cylinder diesel engine, as the same time,analyzing and select the computational models detailed about the turbulent motion of thegas-phase, the turbulent dispersion and the ignition and combustion process in the combustionchamber, and then using three-dimensional CFD simulation software AVL FIRE for a highpower density diesel engine simulation calculations. Construct geometric models andcomputational models of the combustion chamber, and meshing, setting initial parameters andboundary conditions, to remain relevant in the case of fixed parameters of the combustionprocess under different injection timing simulation calculation. According to the simulationresults, this paper analysed emphatically the velocity field and temperature field, mixingdegree of hydrocarbon, and changes of indicated power, maximum explosion pressure incombustion chamber, summarized the different effect of injection advance angle on spraycombustion process. Analysis results indicated that: Combustion chamber velocity field did not vary significantly with the change of injection advance angle; Increases of injectionadvance angle did make the cylinder hydrocarbon mixture faster, more uniformandcombustion more better, while prolonging the ignition delay.This would increase themaximum pressure, temperature and instantaneous heat release rate, help to enlarge indicatedpower; The maximum explosion pressure and maximum temperature rise would cause anincrease in NOx emissions, reduced fuel combustion causes Soot emissions.