A numerical study on heat transfer characteristics of a mesoscale combustor partially filled with wire meshes

Abstract

Porous media are often inserted into micro-/meso-scale combustors for flame stabilization. The heat transfer processes involved are very complicated which still need to be comprehensively investigated. In the present study, the coupled heat transfer processes between gas phases and both the porous media and tube wall of a meso-scale combustor partially filled with wire meshes were numerically analyzed. First, it is found that there exists a heat loss segment (i.e., heat is transferred from near-wall gas to wall) on the inner wall of the porous zone when the inlet mixture velocity is not high enough (≤0.4 m/s), but this phenomenon vanishes as the inlet velocity is further increased. Meanwhile, the porous zone can be divided into two sub-regions, i.e., a heat recirculation zone and a heat loss zone. Interestingly, the boundary shape of these two zones will be inversed with the increase of inlet velocity. Furthermore, the heat recirculation efficiency of inner wall changes non-monotonically with an increasing inlet velocity, which differs from the variation trend of the scenario with a full insertion of porous media reported in the literature. However, the heat recirculation efficiency of the porous media decreases monotonically versus the inlet velocity. In summary, this study unraveled that the flame location and heat release rate vary with the inlet velocity, which affects the temperature distributions of both porous media and tube wall, and this in turn acts on the two pathways of heat recirculation of the combustion system.