Numerical Investigation of the Effect of Ignition Area on the Subsequent Flame Propagation Behavior

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In this paper, the effect of ignition area on the propagation of a laminar premixed flame is investigated numerically in a two-dimensional channel. A single-step irreversible overall exothermic chemical reaction is applied to model combustion chemistry. The time-dependent system of governing equations for reacting flows is discretized using the finite volume method (FVM) on the hexahedral structure grid cells. The discretized system of equations is solved by adopting Front Flow Red, a multi-scale and -physics computational fluid dynamics (CFD) solver. The computed results show that the flame oscillates during the propagation owing to the strong roll-up of the vortices generated by the strong shear layer originating from the sudden high gas expansion flow at the large ignition area. The instantaneous acceleration of the vortices increases the flame surface area which gives rise to higher propagation speed; consequently, combustion time is shortened. These results suggest that the rapid increase in flame surface, caused by the large ignition area induced strong vortices, could be one of the potential methods in improving combustion efficiency by reducing the burning time in the internal combustion devices.