A set of experiments were conducted to determine the characteristics of the combustion species emissions and heat transfer from an premixed slot butane/air Bunsen flame jet impinging on a cold flat plate. The Reynolds numbers were selected to be 1200 and 1700, which were the representative of the laminar and the transitional flame, respectively. The dimensionless nozzle-to-plate distances were 2 and 6, representing small and moderate distances, respectively. All the tests were carried out under an equivalence ratio of 1. It was found that the enhancement of heat transfer of Reynolds number was significant only in the impingement and the early wall jet regions because combustion occurred solely in this region. Beyond this, no combustion was observed. The flame reaction zone occurred around the stagnation point for the transitional flame under moderate nozzle-toplate distance because of the increased turbulence and the considerable high velocity when the flame impinged on the plate. A cool central core with low heat fluxes and a great amount of unburnt hydrocarbon and oxygen was found when either the flame became laminar or the nozzle-to-plate distance was small. The rectangular nozzle shape determined a nonuniform fuel/air gas flow with more gas exiting along the nozzle width direction than the nozzle length direction. This resulted in stronger combustion and higher heat transfer rates along the nozzle width direction than along the nozzle length direction in the impingement and the early wall jet region. This effect became more pronounced when the nozzle-to-plate distance was small. This paper presents the intrinsic relationship between the heat transfer characteristics and the combustion species emissions in detail.
|Number of pages||9|
|Journal||Journal of the Institute of Energy|
|Publication status||Published - Sep 2003|