摘要： 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 modifcation are used to prepare biomimetic structured surfaces with diferent wettability. The impingement processes of diesel and n-butanol sprays on the walls under diferent conditions are experimentally investigated. As the surface oleophilicity increases, the spreading radius of wallimpinging sprays decreases. At about 5 s after the fuel injections, the fuel spray droplets hit the walls for the frst time, and the secondary breakup and rebound occur. The mixture concentrations of diferent 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 fux to the fuel droplets in diferent 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.

关键词: 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 modifcation are used to prepare biomimetic structured surfaces with diferent wettability. The impingement processes of diesel and n-butanol sprays on the walls under diferent conditions are experimentally investigated. As the surface oleophilicity increases, the spreading radius of wallimpinging sprays decreases. At about 5 , s after the fuel injections, the fuel spray droplets hit the walls for the frst time, and the secondary breakup and rebound occur. The mixture concentrations of diferent 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 fux to the fuel droplets in diferent 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.

Key words: Spray-wall impingement , · Morphological development , · Air–fuel mixture concentration , · Surface wettability , · Wall temperature , · Ambient pressure

中图分类号: 

• Spray-wall impingement