船用中速柴油机冷启动工况下缸壁燃油附壁研究

At present, there is a lack of diesel engine cold start conditions of fuel droplets attached to the cylinder wall process research and mechanism analysis, the study for a type of marine medium-speed diesel engine piston top land ablation phenomenon,multi-dimensional computational fluid dynamics (CFD) software is used to explain the mechanism of fuel adhesion to the cylinder wall corresponding to the ablation area of the piston top land. The results show that, in the low-speed cold start conditions, due to a large number of diesel droplets hitting the wall of the cylinder combustion area is concentrated in the vicinity of the wall of the combustion chamber and near the position of the injection hole, the middle area of the injection path forms a low-temperature region, the diesel fuel injected at the later stage of the injection phase is located mainly in the low-temperature region resulting in a poorer atomisation effect, this part of the incomplete evaporation of floating liquid oil droplets is driven by eddy current in the cylinder at the late stage of combustion attached to the cylinder wall. Diesel engine in the cold start conditions after many cycles of operation, the cylinder wall attached to the wall oil film mass and the top area of the gas ring increased the cumulative fuel mass, oil film distribution area and eddy current direction, eddy current strength related.