The gasoline direct injection (GDI) nozzle geometry impacts the quality of the spray and the mixture of fuel and air, which in turn affects the combustion and emission performance of the GDI engine. We have proposed a new non-circular orifice of GDI injector, and Mie-scattering experimental study was conducted to investigate the effects of circular and elliptical orifices on a GDI injector spray under various injection pressures conditions. The results indicated that a swallowtail-like spray structure was first captured in the major view plane of the elliptical GDI injector with a large aspect ratio of 4, while this structure was not visible in the minor view plane. The penetration of elliptical spray was shorter than that of circular orifice spray, and the use of elliptical spray was helpful to avoid the wall-wetting under the GDI engine cold start condition. The elliptical spray cone angle fluctuation amplitude and frequency were greater than the circular nozzle. Moreover, the larger spray projection area of elliptical spray indicated that the use of elliptical orifice can increase the mixture quality. Furthermore, the air entrainment mass of elliptical spray was larger than that of circular spray at high injection pressure and the results confirmed that the mixture quality of fuel and air can be increased effectively by using an elliptical orifice combined with high injection pressure.

中文翻译：

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非圆孔对GDI喷油器喷雾和混合特性影响的实验研究

汽油直喷 (GDI) 喷嘴几何形状会影响喷雾质量以及燃料和空气的混合物，进而影响 GDI 发动机的燃烧和排放性能。我们提出了一种新的GDI喷射器非圆形孔口，并进行了米氏散射实验研究，以研究圆形和椭圆形孔口在各种喷射压力条件下对GDI喷射器喷雾的影响。结果表明，在大纵横比为4的椭圆GDI喷油器的主视平面中首先捕捉到了燕尾状喷雾结构，而在小视平面中看不到这种结构。椭圆喷雾的穿透力比圆孔喷雾短，椭圆喷雾的使用有利于避免GDI发动机冷启动工况下的湿壁现象。椭圆形喷雾锥角波动幅度和频率均大于圆形喷嘴。此外，椭圆喷雾较大的喷雾投影面积表明使用椭圆孔可以提高混合质量。此外，在高喷射压力下，椭圆形喷雾的空气夹带质量大于圆形喷雾，结果证实，椭圆形孔口与高喷射压力相结合可以有效提高燃油和空气的混合质量。椭圆喷雾较大的喷雾投影面积表明使用椭圆孔可以提高混合质量。此外，在高喷射压力下，椭圆形喷雾的空气夹带质量大于圆形喷雾，结果证实，椭圆形孔口与高喷射压力相结合可以有效提高燃油和空气的混合质量。椭圆喷雾较大的喷雾投影面积表明使用椭圆孔可以提高混合质量。此外，在高喷射压力下，椭圆形喷雾的空气夹带质量大于圆形喷雾，结果证实，椭圆形孔口与高喷射压力相结合可以有效提高燃油和空气的混合质量。