Effect Of Fuel Injection Strategy On Performance Of Gasoline/Ethanol Dual Fuel Engine

In the current energy and environmental conditions,energy conservation and environmental protection have become the focus of engine technology development goals.As a renewable alternative energy,ethanol has more advantages and has become the focus of scholars.At this stage,in the ethanol direct injection(EDI)+ gasoline inlet injection(GPI)engine,due to the high viscosity and the latent heat of vaporization of ethanol,the effect of cooling,the mixture formation process,the wallfilm mass and evaporation of ethanol,combustion and emissions still needs to be studied in depth.In this paper,the single-cylinder four-stroke air-cooled engine of Yamaha YBR250 was used as the basic engine to realize the modification of direct injection of EDI + GPI in cylinder.This engine can control the ethanol injection system and the gasoline injection system separately,which can realize continuous adjustment of injection timing and injection pressure.Using the commercial software AVL Fire to realize a three-dimensional experimental engine model and verify the rationality of the model,the engine's working process can be numerically simulated to realize the mixture formation,combustion and emission visualization.This paper mainly conducts experimental research and simulation calculation on the working process of EDI+ GPI engine.Firstly,the effects of injection timing and injection pressure on engine performance were studied experimentally.Furthermore,the engine model was realized by AVL Fire,which can simulate different working conditions.The experimental and simulation results show that: in EDI early spray conditions,ethanol is fully evaporated,but ethanol has no obvious effect on cooling in the cylinder,which can results higher combustion temperature and higher NO emission.As the EDI injection time lags to 150 °CA BTDC,the in-cylinder fuel concentration zone gradually shifts to the near wall side,the combustion effect deteriorates,and the CO and HC emissions gradually increase.The injection pressure has little effect on the early injection conditions,and has a great influence on EDI injection time of 100 °CA BTDC conditions.Under the injection pressure of 4 MPa,rich combustion zone near the spark plug side is easy formed in the cylinder,and the combustion effect and emission effect are better.Different working conditions indicate that,the injection pressure promotes the evaporation of the direct injection fuel and also increases the amount of fuel hitting the wall.