Numerical Study of the Mixture Formation and Combustion Characteristics in Gasoline Direct Injection Engines with Conical Spray

IN order to improve the phenomenon of wall wetting caused by GDI engine injecting fuel directly into the cylinder. Based on the characteristics of small particle size, strong diffusivity and short penetration distance of the conical spray, a self-built laser ultra-high imaging system is used to validate the conical spray model in this study. The numerical and experimental results are found to be in good agreement by comparison. And numerical analysis of a four-stroke GDI engine with a conical injector under low engine speed was carried out to examine the effect of intake temperature on the mixture formation process and combustion events under different injection strategies. The results indicated that the mass of evaporation fuel was increased with the intake temperature increased from 273 to 300 and 330 K, and the peak pressure in the cylinder increased by about 19.6 and 45.7%. As the intake air temperature increases, the in-cylinder equivalence ratio distribution shows better uniformity. In addition, the maximum peak of the pressure in the cylinder is about 2 MPa larger than the minimum peak under different injection strategies. The different injection strategy from single to double and triple resulted in the earlier and higher in-cylinder pressure, resulting in more complete combustion and improved combustion.