Experimental Investigation of Turbulent Boundary Layer Flashback Limits for Premixed Hydrogen-Air Flames Confined in Ducts

This article discusses the results of experimental investigation of turbulent boundary layer flashback limits for premixed hydrogen-air flames confined in ducts. A tube burner experiment was set-up to double-check the findings of the channel rig. Unconfined flashback experiments were carried out by stabilizing the flame on top of the pilot burner in free atmosphere. A confined flame configuration was achieved by simply fixing a ceramic ring with a diameter higher by 4 mm on top of the pilot burner. Flashback measurements with unconfined flame holding neatly reproduced literature values for fully premixed, atmospheric H₂–air mixtures and turbulent flow. The results of unconfined and confined tube burner experiments were plotted. The results showed that the drastic decrease of wall flashback stability for confined flames was the very same for both, tube and channel.