Full-cycle firing simulation of a pent-roof spark-ignition engine with visualization of the flow structure, flame propagation and radiative heat flux

Abstract

A numerical study is made of how the complex geometry of a pent-roof spark-ignition engine influences the flow field, the flame propagation and, novelly, the instantaneous radiative heat flux. The solver integrates a generalized weighted-sum-of-grey-gases-discrete transfer method radiation model into the computational fluid dynamics code KIVA-II also modified to enable the simulation of open ports and canted valves, wave action effects in the exhaust and mixing-controlled combustion. The full-cycle mean pressure variation is in good agreement with measurements. The overall burning angle of 37° crank angle and peak radiative flux of 210 kW/m2 are also plausible on the basis of published data. Finally, remarkable insight is gained into how the head geometry and flow structure influence flame propagation and in turn how this governs the spatial and temporal variation in radiative heat flux on the cylinder walls.