An experimental study of distorted tulip flame formation in a closed duct

The dynamics of a distorted tulip flame in a closed duct has been experimentally and numerically investigated [Xiao et al., Combust. Flame 159 (2012) 1523–1538]. In the present work, the distorted tulip flame formation and the flame evolution after its complete formation is studied to provide further insight into the formation process of the tulip flame distortions. The schlieren images show that a second distorted tulip flame forms with a cascade of secondary cusps on the primary tulip lips just before the collapse of the first one. The pressure wave triggered by the first contact of the flame with the sidewalls is responsible for the periodic flame deceleration and plays an important role in the formation of tulip flame distortions. The close analogy of the distorted tulip phenomenon to the flame inversion which results from the interaction of a convex flame with a shock wave suggests that the sudden flame deceleration acts in a similar way via the Taylor instability in the formation of the distorted tulip flames.