Experimental study on spray and evaporation characteristics of diesel-fueled marine engine conditions based on optical diagnostic technology

The spray and evaporation characteristics of injector used in the large marine diesel engine directly affect the combustion and emission performance of marine engine. But these characteristics are rarely studied. In this work, three kinds of optical diagnostic technologies (backlight high speed imaging technique, UV-LAS and LIF/MIE) were applied to measure the spray liquid and vapor penetrations, spreading angles, SMDs and the distribution of fuel vapor mass of an injector used in the large marine engine under different conditions. The detailed description of the experiment setups and principle of the three optical diagnostic techniques are provided in this work. The experimental results show that the liquid and vapor penetrations decrease with increasing the ambient density. Increasing the ambient temperature can reduce the liquid penetration, but has no obvious effect on the vapor penetration. For spreading angle, the ambient temperature and ambient density are the main influence factors. Increasing the injection pressure is an effective method to reduce SMD, and also the ambient temperature acts as an important role in the fuel evaporation process. What's more, the empirical correlations of spray tip penetrations and SMDs have been updated to fit the spray characteristics of marine diesel engine injector. In general, this work is helpful to understand the spray and evaporation characteristics within diesel-fueled marine engine conditions, and can provide valuable direction for the design of marine engine combustion system.