On non-premixed flames of dual porous cylinders in tandem

Abstract

A porous burner is one of the most efficient combustion devices nowadays due to its recycling features of heat and burning performance. To exploit its advantages for a wide range of external fields, we propose a novel arrangement in terms of tandem porous cylindrical burners and investigate the applicability, specifically on the extension of extinction limits under forced convection. A key parameter is the separation distance (L), presented as a ratio to the cylinder diameter (D). The results of paired cylinders in terms of various experimental and simulation techniques demonstrate superior features of flow pattern, specifically on its stabilization, and thermal interaction achieved by using the tandem array, which led to widened extinction limits at the same total fueling rate. It was found that the extension of the extinction limit reached the maximum near L/D = 1.4. A smaller L/D may discourage entrainment of air into the gap between the cylinders due to inhibition of large vortices, causing the reaction zone to move outward from the gap where the flow is relatively stable. For a larger L/D, the performance degraded due to degeneration of favorable thermal interactions behind the cylinders and excess cold air drawn into the gap by strong vortices.