Experimental investigation of atomization characteristics at low temperature environments during diesel engine cold start

Exploring the atomization characteristics of fuel in low -temperature environments is crucial for improving the cold start performance of diesel engines. In this work, based on LIEF-PIV laser testing technology, a diesel engine cold start fuel atomization experimental system was built, which could simulate the internal environment of a diesel engine's cylinder during cold start. The concentration and velocity distributions of free -jet spray and wallimpinging spray at low temperature were measured experimentally. The results showed that the decrease in ambient temperature had a significant impact on the rate of evaporation of fuel droplets, which was mainly reflected in two aspects: the total evaporation of the fuel and the uniformity of the distribution of vapor phase. The decrease in fuel temperature led to a decrease in the conversion efficiency of vapor/liquid phases of the fuel. When the fuel temperature was -20 degrees C, the distribution range of vapor equivalence ratio near the wall area was 0.11-0.59, which is significantly lower than the other two conditions. In addition, the increase in environmental pressure resulted in a certain decrease in the maximum flow velocity and turbulent flow energy of the mixture, with an average decrease of 0.32 m/s in the maximum flow velocity at the three fuel temperatures of 0 degrees C, -20 degrees C, and -40 degrees C.