Numerical Simulation of n-Heptane Spray Combustion in a Porous Medium Burner

A two-dimensional numerical simulation study is conducted to investigate the combustion process of n-heptane spray in a porous medium burner (PMB) based on the previous experimental work performed by this research group. In order to adapt the model for the conditions of different wall temperatures and different splash Mach numbers, the wall-impingement model in this study is based on the model by O'Rourke and Amsden and the interaction mechanism between the spray droplets and the wall is optimized through user-defined functions (UDFs). The effects of air inlet velocity, injected fuel quantity and preheating temperature on spray combustion are analyzed. The results show that the downstream velocity of the combustion flame increases when the inlet air velocity increases or the fuel injection rate decreases or the preheating temperature decreases. Under the same equivalence ratios, the flame propagation velocity increases as the increase of the dimensionless gas-oil joint effect parameter. The flame area also increases with the increase of inlet air velocity, but the rate of increase in the flame area gradually decreases as the reaction proceeds. An initial preheating temperature of 1060 K is conducive to the stable combustion of n-heptane spray for flame lengths less than 0.060 m.