Abstract
In order to estimate spark-ignitability in a fuel-air mixture, turbulent Karlovitz number Ka is used, which is calculated based on the local velocity and equivalence ratio. This estimation is applied some LES or RANS calculation results of a natural-gas jet with impingement on a cavity wall. The local Ka is estimated from flame thickness, laminar burning velocity and characteristics time-scale of turbulence. For appling the LES result, the turbulence time scale is calculated by Smagorinski's model. For appling the RANS result, that is calculated based on k and ε. The result shows that the spark-ignition at the point of Ka<50 cause a stable combustion.
