HEAT TRANSFER CHARACTERISTICS OF AN IMPINGING BUTANE/AIR FLAME JET OF LOW REYNOLDS NUMBER

An experimental study was performed to determine the heat transfer characteristics of a premixed butane/air round flame jet, of low Reynolds number, impinging upwards normally on a flat rectangular plate. The effects of the exit Reynolds number and equivalence ratio of the flame jet, and the distance between the nozzle and the impingement plate, on the thermal performance of the jet were examined. The range of Reynolds numbers was selected to cover the laminar to the transitional flow conditions. The investigations were conducted with equivalence ratios corresponding to the fuel-rich, stoichiometric, and fuel-lean conditions. The nozzle-plate distance was varied from 1d to 8d. Within the range of Reynolds numbers investigated, the highest Nusselt numbers were obtained at the equivalence ratio of φ = 0.85 when the nozzle-plate distance was maintained at 5d. At the stoichiometric condition, the highest Nusselt number was obtained at the nozzle- plate distance of 6d. Nondimensional correlations were obtained from the experimental results and presented to predict the maximum Nusselt number and average Nusselt number for laminar flame jets as a function of the nozzle-plate distance, Reynolds number, and equivalence ratio.