For the frequent ablation of piston during the operation of diesel engine at low temperature, the failure phenomenon was reproduced through a simulated low
temperature environment test. Threedimensional simulation methods were used to analyze the microscopic difference of combustion process at 25 ℃ and 40 ℃. The comparison and analysis of the combustion heat release process, the parameter curves of fuel and air mixing process and the threedimensional cloud diagram illustrated the characteristics of fuel and air mixing and combustion heat release for the detonation during the process of incylinder piston ablation. The simulation results show that mechanical load and thermal load have a tendency to increase simultaneously at low temperature. The maximum pressure rise rate increases by 35.4%, the cumulative wet wall volume increases by 12.7%, and the peak of transient heat release rate increases by 50.7% when the temperature decreases from 40 ℃ to 25 ℃. The fuel spray impinges on the wall, expands toward the valve pocket and then enters the side gap. A strong pressure oscillation hence occurs near the top dead center, which promotes pressure stratification so that the local maximum combustion pressure reaches 20 MPa and the maximum combustion temperature is up to 2 700 K.
