Premixed flame impingement heat transfer with induced swirl

Experiments were performed to study the heat transfer characteristics of a swirling premixed flame impinging vertically normal to a horizontal plate. The effects of Reynolds number (Re), equivalence ratio (Ф) and nozzle-to-plate distance (H) on the heat flux were examined. Comparisons were also made between the heat transfer behaviors of the swirling premixed flame (SPF) with a non-swirling premixed flame (PF) operating under the same conditions. Compared with the PF, the swirling flows in the SPF increase the entrainment of ambient air and induce a faster radial spreading rate of the flame jet. Therefore, the SPF provides a larger heating area and produces a more uniform radial heat flux distribution. For both the SPF and PF, the heat flux increases with Re due to the more complete combustion occurring at higher Re. For the SPF, the heat transfer increases with Ф, while it decreases with Ф for the PF because the stronger entrainment of ambient air in the SPF supports a more complete combustion. A smaller H is required for the maximum heat transfer to occur for the SPF.