Experimental Study Of The Interaction Between A Turbulent Flame And A Cooling Air Film

Abstract

The current experimental study is focused on the analysis of the interactions between a V-shaped lean turbulent premixed methane-air flame and a parietal cooling air film generated by means of a splash-cooling system. The flame structure, the reactive aerodynamics and the wall temperature are simultaneously studied by implementing planar laser-induced fluorescence of the OH radical (OH-PLIF), reactive particle image velocimetry (PIV) and surface intensity-ratio phosphor thermometry (PT). Results show that the mean flow field and the mean flame topology significantly differs according to the level of blowing ratio. Further joint correlations of experimental measurements highlight various FCAI regimes. For blowing ratios below unity, a common flame-wall interaction process occurs and the air film has a limited influence on the flame dynamics. Increasing the blowing ratio enables to establish a cooling air film at the wall. Though it effectively increases the level of thermal protection, it does not have much influence on the flame topology. Eventually, for larger blowing ratios, the flame dynamics is piloted by the shear layer dynamics, associated with strong flow strain. The flame is pushed away from the wall and is located in the outer region of the shear layer. The cooling effectiveness is not improved anymore and shows no more dependencies with the blowing ratio.