A Story of "Chrysanthemum Flame"

Abstract

The downward propagating flame of NH₃/O₂/N₂ mixture in a top open combustion tube were captured by high speed cameras. In the propagation process the flame changes its shape and structures depending on the location of the flame. One of the critical moments of the flame is transition to the parametric instability, which shows a highly structured cellular pattern followed by steep growth of pressure perturbation called as combustion instability. The authors received the highest award in 2022 Beautiful Flame Photo Contest in 60^th Symposium (Japanese) on Combustion. The name of picture is "Chrysanthemum Flame" as shown in the right, which represents an instant of transition to the parametric instability of the propagating flame. In this paper the story behind the flame picture including method of photographing, theoretical background, and significance of the picture from the view of combustion science are described.