抄録
A flame kernel initiation of methane-air combustible mixtures in the spark ignition process has been numerically investigated using a two-dimensional theoretical model including a detailed description of gas phase chemical kinetics, shock capturing scheme and transport parameters. The two-dimensional cylindrical coordinate system has been employed and assumes axial symmetry, and numerical domain is bounded by a solid wall. A chemical reaction scheme for a methane-air mixture consists of 34 species and 164 reactions. The thermodynamics and transport properties have been evaluated by a theoretical model in detail. In order to capture the blast wave behavior, a TVD scheme is employed in all equations. Fourth-order Runge-Kutta scheme is used to integrate a set of conservation equations in time. In the early stage, the behavior of the hot gas is dominated by a flow which is induced by the blast wave with an application of high ignition energy. Although a high temperature gas, which spurts out from the electrode gap, quenches, the gas at the electrode gap is self-sustained with an application of low ignition energy. After a certain period of time, the flame kernel gradually grows out of the electrode gap. The induction time of the flame kernel initiation increases with decrease in ignition energy. In the process of the flame kernel development, the local equivalence ratio at the electrode gap is larger than that in the outer region with an annlication of low ignition energy Diffusion of methane into the hot as region is recognized.
