Investigation of Wall Temperature Effect on Flame Quenching Distance during the Warm-up Period of an SI Internal Combustion Engine

The internal combustion engine’s warm-up period is one of the most important sources of emissions, especially unburned hydrocarbons (UHC). Due to the low temperature of combustion chamber wall during the warm-up period, the flame is quenched rapidly near the walls and piston surface and the air-fuel mixture in the vicinity of the wall does not burn and leave the combustion chamber unburned which increases UHC emissions of internal combustion engines during the warm-up period. In the current study, using MATLAB R2018b software and numerical solution methods, a code is developed based on XU7 engine data to determine the effect of wall temperature on the flame quenching distance. The results showed that by increasing the cylinder wall temperature, flame quenching distance during the engine warm-up period, for two cases of constant and pressure based Peclet number, was decreased by 46 and 22%, respectively. The results also indicated that the flame quenching distance had a downward logarithmic behavior over time, which is the opposite of the thermal behavior of the combustion chamber walls during the engine warm-up period, which is an upward logarithmic behavior.