关键词: LES-PDF;旋流火焰;熄火;通道结构

Abstract: To deeply understand the non-premixed swirl flame，the effects of two burner exit geometries on the non-premixed swirl flames modes were studied by performing OH-PLIF，PIV measurements and coupling LES with PDF combustion model numerically. The results showed that the stochastic PDF method can predict the swirl flow fields and detailed flame structures including local extinction. Two different quarl geometries played significant roles on the flow fields thus leading to the local extinction and lift-off. The recirculation zone is smaller in the non-quarl case which causes a more serious quenching state. Meanwhile，at the stoichiometric equivalence ratio，the OH and CH₂O distributions in the no-quarl exit were broader than the quarl exit at the low temperature regime. This indicated that many low-temperature reactions took places，providing beneficial conditions for the lift-off flame stabilization.

Key words: LES-PDF;Swirl flame;Local quenching;Quarl structure geometry