Wandel, Mastorakos, Cant, Swaminathan, Chakraborty (University of Liverpool)

Three-dimensional Direct Numerical Simulations with one-step chemistry have been carried out in order to understand the spark ignition phenomena in a non-homogeneous mixture. The effects of spark energy and spark location for sustainable combustion are studied by varying spark power, duration, and spark location in the mixture fraction space.

Depending on the spark power and spark location, one may encounter twin or triple flames in the present configuration (see Fig.1). The statistical behaviour of the edge flame propagation is studied in terms of edge flame speed behaviour with respect to scalar dissipation rate and local flame curvature. This study eventually leads to the modelling of edge flame speed with respect to the various parameters, namely, turbulence frequency, scalar dissipation rate and flame curvature. The present study will subsequently lead to the modelling attempt of the ignition process using Conditional Moment Closure (CMC) methodology.

Figure 1.  Typical triple flame structure following a localised energy deposition at a point with stoichiometric mixture, visualised by the magnitude of fuel consumption rate at x-y plane at z = 0.5. The spark location corresponds to x = y = z = 0.5. The white line shows the stoichiometric mixture fraction contour.