Present work studies experimentally the flame characteristics of a premixed natural gas/air mixture in a porous-free flame (PFF) burner, and also it is compared with a conventional porous burner. For the PFF burner a hole is created at the center of the porous foam, which has a porosity of 87%, height of 22 mm and diameter of 90 mm, making a combination of a free flame and a flame in the porous region. Effects of the hole diameter, d = [6, 9 and 12 mm], foams pore density, λ = 10, 20 and 30 pores per inch (ppi), and foam materials (SiC and Al₂O₃) on the axial temperature distributions of the foams as well as on the lean and rich limits are examined. The results show that for a fixed foam pore density and foam material, the axial temperature of the foam in the PFF burner is lower than that of the porous burner. Also, for the PFF burner an increase in the hole diameter leads to a decrease in the axial temperature. Compared to the PFF burner, the flame in the porous burner is stabilized at a lower equivalence ratio (leaner mixture), while the PFF burner extends the rich limit of the flame. Additionally, the diameter of the hole found to have insignificant influence on the lean and rich limits. Results further show that an increase in the foam’s pore density leads to a decrease in the axial temperature of the foam and the lean/rich limit of the flame. The axial temperature of the SiC foam found to be higher than that of the Al₂O₃ porous foam. Furthermore, the lean and rich limits are extended by deploying the SiC porous foam.

目前的工作是通过实验研究无孔火焰（PFF）燃烧器中天然气/空气混合物的火焰特性，并将其与常规多孔燃烧器进行比较。对于PFF燃烧器，在多孔泡沫的中心开有一个孔，该孔的孔隙率为87％，高度为22 mm，直径为90 mm，在多孔区域中结合了自由火焰和火焰。孔直径d = [6、9和12 mm]，泡沫孔密度，λ=每英寸10、20和30个孔（ppi）和泡沫材料（SiC和Al ₂ O _{3）的影响}）检查泡沫的轴向温度分布以及稀薄和浓稠极限。结果表明，对于固定的泡沫孔密度和泡沫材料，PFF燃烧器中泡沫的轴向温度低于多孔燃烧器的轴向温度。同样，对于PFF燃烧器，孔直径的增加导致轴向温度的降低。与PFF燃烧器相比，多孔燃烧器中的火焰稳定在较低的当量比（较稀的混合物），而PFF燃烧器扩展了火焰的浓限。另外，发现孔的直径对稀薄度和浓稠度极限没有显着影响。结果进一步表明，泡沫的孔密度的增加导致泡沫的轴向温度降低和火焰的稀/富极限。₂ O ₃多孔泡沫。此外，通过部署SiC多孔泡沫扩展了贫富限制。