中文摘要：

超负荷工况是船舶柴油机设计和运行中应考虑的一个重要工况，为更好地提高LNG/柴油双燃料柴油机超负荷工况下的动力性、经济性和环保性，应用Chemkin-pro程序对超负荷工况下双燃料柴油机的燃烧性能进行初步研究分析。在超负荷工况下，当甲烷替代率为70%时，缸内温度最高点和压力最高点都有所降低且滞后；当甲烷替代率为50%时，缸内燃烧温度和压力的变化与纯柴油时基本一致。通过分析得出，在超负荷工况下，甲烷替代率为50%比70%更合理，且能保证柴油机的动力性、经济性和环保性。

英文摘要：

Overload is one of the important loading conditions to be considered in the design and operation of marine diesel engines.In this paper,Chemkin-pro program is used to analyze the combustion characteristics of the dual fuel engine under overload conditions to improve the dynamic property and economic efficiency of the engine,and to make the engine more environmental friendly.It is found that the maximum temperature and the maximum pressure inside the cylinder are decreased and delayed when the methane replacement rate is70%under overload conditions,but the variation of the temperature and pressure inside the cylinder is almost the same as that with diesel when the methane replacement is50%.So the conclusion is that50%methane replacement is more reasonable than70%replacement under overload conditions,which is beneficial for the dynamic property,economic efficiency and environmental friendliness of the engine.