Experimental study of the stabilization process of a non-premixed flame via the destabilization analysis of the blue ring flame

The flame stabilization phenomenon remains a crucial issue. The experimental study of flame stabilization behind a tulip-shaped flame-holder is addressed in this paper. The process leading to the transition between specific modes – the blue ring flame and the instable ring – of a non-premixed flame stabilized on a tulip-shaped bluff-body is detailed. The aim of this study is to provide an accurate description of the destabilization of specific combustion modes, which enables a further understanding of the entire stabilization mechanism. The aerodynamic and mixing fields are described by laser Doppler anemometry and concentration measurements by sampling probe respectively. The behaviour of shear layers developing at the wake and jet boundaries are characterized by means of a spectral analysis of the fluctuating radial velocity. Results show that the destabilization process is related to the intensification of hot gas recirculation, inducing an upheaval of the dynamical condition of stabilization and a transition of mixing phenomena.