Direct injection is an attractive technology for improving fuel economy and engine performance in gasoline engines. However, the adhered fuel formed on the piston surface has significant influence on the combustion efficiency and emissions. To obtain a better understanding of fuel adhesion, this work involved investigation of the spray and impingement on a flat wall through a mini-sac injector with a single hole. Different impingement distances and injection pressures were investigated. The evolution of the impinging spray was obtained by the Mie scattering method. The refractive index matching method was applied to measure fuel adhesion. The mass, area, and thickness of adhesion under different conditions were compared. The experimental results show that the fuel adhesion on the wall increases significantly with a large impingement distance. Moreover, the maximum thickness increases and the thickness uniformity of the fuel adhesion declines under a large impingement distance condition.

中文翻译：

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喷射冲击距离对直喷汽油机活塞顶部燃油附着力的影响

直接喷射是提高汽油发动机燃油经济性和发动机性能的一项有吸引力的技术。但是，在活塞表面形成的粘附燃料对燃烧效率和排放有显着影响。为了更好地了解燃料粘附，这项工作涉及通过带有单孔的微型囊式喷射器对平坦壁上的喷射和撞击进行研究。研究了不同的冲击距离和注射压力。撞击喷雾的演变是通过米氏散射法获得的。使用折射率匹配法测量燃油附着力。比较了不同条件下粘附的质量、面积和厚度。实验结果表明，燃料在壁上的附着力随着撞击距离的增加而显着增加。