Enhancement of flame stabilization ability of a miniature tubular combustor by filling T-shaped porous media

Porous media combustion is a frequently adopted technology for flame stabilization. However, the solid matrix has a redirection influence on incoming flow, which reduces boundary layer thickness and weakens the flame stabilization ability to some extent. Our previous experimental investigation showed that C4H10/air flames were suspended above the porous media that filled in a miniature tubular burner (ID = 6 mm). The upper velocity limit (i.e., blow-off limit) turned out to be 0.55 m/s, which was only slightly higher than the laminar burning velocity (similar to 0.4 m/s). To enhance flame stabilization ability of this combustor, a method of filling a T-shaped porous zone was proposed in this study. Total length of the porous zone is 10 mm while the protruding part length (L-22) is variable. Effect of L-22 (L-22 = 0, 2, 4, 6, 8 mm) on the blow-off limit of stoichiometric C4H10/air flames was numerical explored. The blow-off limit increased monotonically with an increasing L-22, reaching 1.05 m/s at L-22 = 8 mm. Analysis demonstrated that due to a larger flow resistance of the protruding part, a lowvelocity zone was formed within it and it was prolonged with the increase of L-22. Meanwhile, a thicker boundary layer was formed near the wall of annual space. Moreover, heat recirculation through the T-shaped porous zone was intensified compared to the original configuration because the central flame front could be immerged within the protruding part. As a result, flame stabilization capability of the combustor was essentially improved by filling a T-shaped porous media.