Atmospheric pressure and oxygen concentration will change with the change of altitude,and engine performance will inevitably appear different from the standard air environment by using EGR. In this paper,the Boost model of an engine was established and verified according to the basic structure and bench test data of engine under standard air environment. The influence of EGR on engine performance and emissions at different altitudes was simulated and studied. The difference between the different atmospheric environments at the same EGR rate was analyzed. Simulation results shows the influence of EGR on en-gine power and economical efficiency is small except full load case,NOx emission is greatly reduced with the increase of EGR rate,but when the EGR rate is high,the Soot emission will worsen sharply,and the performance and Soot emission of engine will be significantly worse at high load with the same EGR rate while altitude increases.%随着海拔的变化，大气压力和氧气浓度都会发生改变，引入EGR后发动机的性能必然会出现不同于标准大气压环境时的情况。建立了某型号发动机的Boost模型，用标准大气压下的台架试验数据对模型进行了标定验证；模拟研究了不同大气压力下EGR对发动机性能和排放的影响，并比较分析了同一EGR率时不同大气压力下发动机性能的差异。结果表明，除全负荷工况外EGR对发动机的动力性和经济性影响比较小，NOx随EGR率的增加会急剧减少，但大EGR率时Soot排放会急剧恶化；同一EGR率时在中高负荷下，随着海拔的增加，发动机的动力性、经济性和Soot的排放会出现明显恶化。
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