火炎詳細シミュレーションにみられる非Flamelet的火炎について

抄録

Practical simulations of combustors are successfully conducted by use of the combustion models based on the laminar flamelet concept. On the other hand, thanks to the recent progress of computer performance, simulations with detailed chemistry and rigorous transport properties are becoming practical about simple flame configurations. In the latter simulations, complicated flame structures are reproduced and sometimes they look largely different from laminar flamelets. The authors succeeded in capturing a hydrogen jet lifted flame by a detailed simulation. The flame consisted of three elements, a leading edge flame, outer island-like diffusion flames, and inner turbulent rich premixed flame. Non-flamelet-like structures were observed in the inner vigorously turbulent part of the flame and they are investigated in terms of the balance between the fuel consumption and the fuel molecular diffusion and the dependency of the fuel consumption on the fuel molecular diffusion. The results show the flames cannot be described by the laminar flamelet concept, because the turbulent eddies can penetrate into the flames to modify the internal structure. New analytical concepts are necessary to understand and to model such kind of flames.