Experimental investigation of flame/solid interactions in turbulent premixed combustion

An experimental study has been carried out to investigate the interaction b etween propagating turbulent premixed flames and solid obstacles. The exper imental rig was configured specifically to allow detailed measurements with laser-based optical diagnostics. A wall-type solid obstacle was mounted in side a laboratory-scale combustion chamber with rectangular cross-section. The flame was initiated, by igniting a combustible mixture of methane in ai r at the center of the closed end of the combustion chamber. The flame fron t development was visualized by a high-speed (9000 frame/s) digital video c amera and flame images were synchronized with ignition timing and chamber p ressure data. The tests were carried out with lean, stoichiometric and rich mixtures of methane in air. The images were used to calculate highly resol ved temporal and spatial data for the changes in flame shape, speed, and th e length of the flame front. The results are discussed in terms of the infl uence of mixture equivalence ratio on the flame structure and resulting ove rpressure. The reported data revealed significant changes in flame structur e asa result of the interaction between the propagating flame front and the transient recirculating flow formed behind the solid obstacle. Combustion images show that the flame accelerates and decelerates as it impinges on th e obstacle wall boundaries. It is also found that the mixture concentration s have a significant influence on the nature of the flame/solid interaction s and the resulting overpressure. The highest flame speed of 40 m/s was obt ained with the unity fuel-air equivalence ratio. Burning of trapped mixture behind the solid obstruction was found to be highly correlated with the fl ame front length and the rate of pressure rise. (C) 2001 Elsevier Science I nc. All rights reserved.