Abstract: The computational fluid dynamics (CFD) method is adopted to study the change rule of heat flux distribution in plateau environment. Three-dimensional numerical simulation of combustion process of diesel engine at different altitudes was carried out. The results show that the Han-Reitz model can be used to obtain the satisfied results when the combustion process is calculated, including the process of combustion gas transferring heat to cylinder wall. With the increase in altitude, the excess air coefficient decreases, the ignition delay period is prolonged, the ignition delays, the combustion is deteriorated, the explosion pressure decreases, and the combustion temperature rises. The higher the altitude is, the greater the spray momentum is. The influence of gas flow on the heat transfer coefficient increases after top dead center, and the effect of air intake flow on the heat transfer coefficient decreases, and the heat transfer coefficient increases with the increase in altitude. Under the influences of heat transfer coefficient, gas temperature of wall and wall oil film combustion, the average heat flux on the wall increases greatly during combustion at high altitude, and the instantaneous average heat flux on the wall increases from 1 000 m to 4 500 m, and the instantaneous average heat fluxes on the cylinder head and piston increase to 30% and 26%, respectively.Key

Key words: dieselengine, plateauenviroment, heatfluxdistribution, numericalsimulation