Experimental Investigation of the Effects of Flame Phenomenology on the Wall Temperature Distribution of Mesoscale Nonadiabatic Ducts

Abstract

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.

Development of planar meso­scale combustor with double narrow slit flame holder and various aspect ratios for micropower generator

“…Studies that examined the flame stability limits and wall temperatures have been examined, but the observed area still tends to be in the area of large equivalence ratio. The flame phenomenon of the circular mesoscale combustor (d=4 mm) has been studied using a methane-oxygen mixture [15]. The study produced a map of flame stability limits and divided into 5 flame modes.…”

“…It has been revealed from previous studies [15] that the use of pure oxygen produces a very high flame propagation speed, consequently the flame stability limit shifts to a rich mixture, this is due to the fact that the flame had a flashback at a low equivalent ratio. Improvement effort has been made to delay the occurrence of flashback by using a double narrow slit flame holder [16] which results showed that the flame stability limit can extend to the low equivalent ratio (lean mixture).…”

Thermal expansion effect on the propagation of premixed flames in narrow channels of circular cross-section: Multiplicity of solutions, axisymmetry and non-axisymmetry

“…The propagation of premixed flame in a tube constitutes a basic configuration in the buildup of miniaturized combustors. Experiments [4][5][6][7][8][9] have shown that the characteristics of the flame propagation regime are sensitive to various parameters such as transport, thermodynamics and conductive properties, composition mixture and tube geometry.…”