HEAT TRANSFER CHARACTERISTICS OF SLOT AND ROUND PREMIXED IMPINGING FLAME JETS

摘要

An experimental study has been performed to determine the heat transfer characteristics of round and slot premixed butane/air flame jets, which were impinging upwards normally on a horizontal rectangular plate. Effect of the burner geometry on the heat transfer coefficient at the jet/plate interface, with the variation of Reynolds number and air/fuel equivalence ratio, has been examined. Round and slot burner nozzles with the same cross-sectional area were tested at a constant nozzle-to-plate distance of 2d. The Reynolds number was selected to range from 1,000 to 1,700, in order to produce a laminar flow. The air/fuel equivalence ratio was extended from 0.95 to 1.3 to produce fuel-lean, stoichiometric, and fuel-rich flames. When compared to the round jet, the slot jet provided more uniform heat flux on the impingement plate, but the peak heat flux was not so concentrated. The slot jet produced different heat flux distributions along the length and width of the impingement plate, and the average heat flux was higher along the direction of the slot width (i.e., the plate width) in the present study, especially when the Reynolds number or the equivalence ratio was increased. The present study provides more information and a comparison between the heat transfer characteristics of round and slot premixed impinging flame jets utilizing a butane/air mixture. Such reports have rarely been reported in the literature.