Heat Transfer by a Two-Dimensional Air Jet Impinging Obliquely on a Flat Surface

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° to 40°, b) nozzle exit-to-plate spacing, z/Dh, in the range of 4 to 12 and c) Reynolds number based on the hydraulic diameter of the slot nozzle in the range of 4049 to 12020. The results are presented in the form of graphs showing the variation of the local Nusselt number as a function of these parameters. The point of maximum heat transfer shifts towards the uphill side of the plate and the maximum Nusselt number decreases from its value at θ = 90° as the inclination angle decreases. The location of the maximum heat transfer region lies between 0 and 3Dh away from the geometrical impinging point and appears to be insensitive to the Reynolds number in the range used in this study. For lower values of inclination angle, the local Nusselt number downstream from the maximum heat transfer point was insensitive to jet exit-to-plate spacing.