Numerical Simulations of Premixed Flame Ignition in Turbulent Flow

The ignition process in a prescribed flow field was investigated in the frame of a 2D thermal-diffusion model. It is assumed that the heat release in the course of chemical reaction has no influence on flow. The latter is obtained by a hydrodynamic model without taking into account chemical reactions. Initial conditions were represented by a fixed size square domain delta filled with hot combustion products with constant temperature. If the flame is ignited at a chosen minimum value of initial temperature this value is referred to as the ignition temperature T-ign for a given size of the hot domain. The minimum ignition energy is determined as a product of ignition temperature and square domain size E-ign = T-ign delta(2). The dependencies of minimum ignition energy on characteristics of time-independent, space-periodic flow field are obtained. The ignition process in the flow field, which is pre-calculated in the frame of the two-dimensional Euler equation for freely decaying turbulence, is also studied. It is found that theoretical results obtained within thermal-diffusion models allow to explain qualitatively some experimental results on the ignition in the turbulent flow.