Injection Parameters And Performance Analysis Of Compound Injection Engines

With stricter emission and fuel economy standards,some automobile factories have introduced compound injection technology to utilize the benefits of both gasoline direct injection(GDI)and intake port injection(PFI)at respective operating conditions.The compound injection technology enables both PFI and GDI with intake port injectors and cylinder injectors.Engines with this technology can get more adaptable mixture and improve combustion quality and engine performances.In this paper,the effects on engine performance of injection parameters are studied.The main contents are as follows:The simulation model was set up in a CFD code and verified through experiments.The process of intake,compression,spray,mixture formation and combustion was simulated with controlling variables method.The controlling parameters were fuel injection proportions,injection timing and injection duration.According to simulation results,the impacts of these three parameters on combustion characteristic and emission were studied,including velocity field and concentration field distribution,film,pressure,pressure rise rate,temperature,releasing heat,heat release rate and Soot,NOx,carbon monoxide,and unburned hydrocarbon.The injection strategy of the engine was determined by the combustion and emission characteristic.The influencing factors of emissions were studied.The soot research included generation process and oxidation process.The effects on the generation and oxidation rate and the net production rate of soot were discussed,including factors of the temperature and concentration of mixture were studied.And the influence on the total nitrogen oxides were studied,including factors of the temperature,the temperature variation with crank angle,the peak value and concentration of the mixture.The performances of PFI and GDI were compared through experiments.