Abstract

To improve the controllability of the wall-wetting process after the fuel spray-wall impingement in internal combustion engines, the methods of laser etching, chemical etching and surface free energy modification are used to prepare biomimetic structured surfaces with different wettability. The impingement processes of diesel and n-butanol sprays on the walls under different conditions are experimentally investigated. As the surface oleophilicity increases, the spreading radius of wall-impinging sprays decreases. At about 5 s after the fuel injections, the fuel spray droplets hit the walls for the first time, and the secondary breakup and rebound occur. The mixture concentrations of different fuels hitting the various walls reach the peak value. Under a higher surface temperature, the peak value of the mixture concentration is mainly related to the heat flux to the fuel droplets in different boiling regimes from the metal surfaces. The concentration of the air–fuel mixture in the near wall region increases with increasing surface oleophilicity, increasing wall temperature and decreasing ambient pressure. Compared with diesel, n-butanol presents a higher air–fuel mixture concentration in the near wall region.

中文翻译：

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仿生结构表面燃油喷雾撞击过程的实验研究

 抽象的

为了提高内燃机燃油喷射壁面撞击后壁面润湿过程的可控性，采用激光刻蚀、化学刻蚀和表面自由能修饰等方法制备不同润湿性的仿生结构化表面。对不同条件下柴油和正丁醇喷雾对墙壁的冲击过程进行了实验研究。随着表面亲油性的增加，壁撞击喷雾的扩散半径减小。喷油后约5秒，燃油雾滴首次撞击壁面，发生二次破碎和反弹。不同燃料撞击各壁的混合物浓度达到峰值。在较高的表面温度下，混合物浓度的峰值主要与从金属表面到不同沸腾状态的燃料液滴的热通量有关。近壁区域空气-燃料混合物的浓度随着表面亲油性的增加、壁温的升高和环境压力的降低而增加。与柴油相比，正丁醇在近壁区域呈现出更高的空气燃料混合物浓度。