Experimental investigation of the effects of flame phenomenology on the wall temperature distribution of mesoscale nonadiabatic ducts

Infrared thermography was used in order to examine the effects of flame phenomenology in mesoscale ducts on the temperature profile of the duct walls. Rich methane-oxygen mixtures of were burned in straight mesoscale ducts of a circular cross-section. Equivalence ratio was varied to produce different flame behaviors, including externally stabilized flames at the tube exit, stationary flame fronts within the tube, and oscillating flame fronts that propagated within the tube. Infrared thermometry was used in order to measure the axial temperature distribution of the duct walls. The temperature distributions were examined as a function of flame phenomenology, and the effectiveness of each behavior in heating the duct and providing a uniform temperature distribution were evaluated. Quartz and steel tubes were used in order to probe the impact of the duct thermal conductivity on the temperature profile, and to investigate why stable oscillating flames can only be established in ducts made of materials with low thermal conductivity. Oscillating flames were found to transfer energy to the duct wall in a substantially more effective manner than a conventional externally stabilized flames at the duct exit and to produce very close to uniform distributions of temperature.