Persistence of Laminar Flamelet Structure Under Highly Turbulent Combustion Persistence of Laminar Flamelet Structure Under Highly Turbulent Combustion

We have investigated the premixed flame structure in highly turbulent flow with a cyclone-jet combustor. Based on the turbulent properties determined by Slot-Correlation method, the condition of U_m<15 m/s belongs to the flamelet regime, and that of U_m>20 m/s belongs to the distributed reaction zone regime on the combustion diagram. Also, we have quantitatively estimated the reaction zone thickness, using the probability of reaction zone existing. Results show that the dependence of reaction zone thickness on equivalence ratio is very similar to those of the experimental values by Yamaoka and Tsuji or the Zeldovich thickness. When the exit velocity is increased, the reaction zone thickness is almost constant for Ka>1. Hence, the persistence of laminar flamelet structure is observed, even when the Kolmogorov scale is smaller than reaction zone thickness. It could be concluded that the reaction region remains undisturbed with thin reaction zone under highly turbulent conditions. These results are useful for modeling turbulent combustion.