The effect of inclination on the heat transfer between a flat surface and an impinging two-dimensional air jet

Abstract

Abstract An experimental study was performed to determine the effect of the inclination of an impinging two-dimensional air jet on the heat transfer from a uniformly heated flat plate. The impingement surface was a stainless steel plate of the same width as the jet nozzle. Local Nusselt numbers were determined as a function of three parameters: (a) inclination angle of the air jet relative to the plate in the range of 90–40°, (b) nozzle exit-to-plate spacing ( z / D ) in the range of 4–12 and (c) Reynolds number based on the hydraulic diameter of the slot nozzle in the range of 4000–12 000 (corresponding to an exit jet velocity from 6.3 to 18.7 m/s). The results are presented in the form of graphs showing the variation of the local Nusselt number as a function of these parameters. The region of maximum heat transfer shifts towards the uphill side of the plate and the maximum Nusselt number decreases as the inclination angle decreases. The location of the maximum heat transfer region appears to fall between 0 and 3 D uphill from the geometrical impingement point, and was found to be insensitive to the Reynolds number in the range used in this study. For low values of inclination angle, the local Nusselt number on the uphill side from the maximum heat transfer point was insensitive to jet exit-to-plate spacing. Correlations are proposed to predict the local Nusselt number as a function of x / D , z / D , θ and Re .