On the "Tulip flame" phenomenon

We present an experimental study of the "tulip flame" phenomenon using high-speed photography. Contrary to most previous studies, the work is in a simplified quasi-constant pressure configuration in a half-open tube. It is shown that the salient features of the different stages of the flame propagation and shape can be explained by a simple geometrical model of the interaction between the flame front and the gas dynamics. In particular, the tulip flame results from an inversion of the flame front curvature caused by the deceleration related to loss of flame surface area. Finally, the experimental results obtained by other authors in closed vessels are in reasonable agreement with the analysis presented.