Experimental study on the dynamical features of a partially premixed methane jet flame in coflow

In this paper we report an experimental investigation of the dynamical features of a propagating partially premixed flame established on a concentric coflow burner. The variation regulation about the propagation and structure characteristics in different inflow condition is analyzed basing on high-speed photography. The results show that 1)In condition of large center jet velocity, transition from turbulent to laminar combustion is exhibited in the process of attaching, reverse transition is observed in the process of blowing out. 2)A stronger rich-premixed center flow mainly enhances the flame propagation in an attaching flame and the local flow velocity in a blowing out flame. 3)The displacement of the flame base and tip accounts for the major change and small-scale oscillation in the flame length, respectively. 4)The flicker of the flame slacks when the propagation state transitions to lifted-off or blowing out from attaching.