柴油机冷起动工况附壁油膜生成特性研究

The temperature and density of the top dead center in the cylinder of the diesel engine are low, the amount of the spray impinges the wall is large, and the fuel film evaporates slowly, so it is easy to produce pool fire during the combustion, which is not conducive to the control of soot emission. In this paper, the influence of different ambient temperature and density on the characteristics of the fuel film during the cold starting of diesel engine is studied by combining the backlight method and the refractive index matching method in the flow constant volume combustion bomb. The results show that the environmental temperature has a great influence on the area, volume and thickness distribution of the fuel film. The peak volume of the fuel film when the ambient temperature is 500 K is 6 times of that when the ambient temperature is 600 K, the fuel film thickness decreases and the distribution tends to be uniform at high ambient temperature, and the proportion of the fuel film with different thickness is less than 15% at 600 K. Under different environmental densities, the evaporation rate of the fuel film is relatively stable, and high density will promote the evaporation of the fuel film.