Heat transfer characteristics of a planar water jet impinging normally or obliquely on a flat surface at relatively low Reynolds numbers

The heat transfer characteristics of a planar free water jet normally or obliquely impinging onto a flat substrate were investigated experimentally. The planar jet issued from a rectangular slot nozzle with a cross section of 1.62 mm × 40 mm. The mean velocity at the nozzle exit ranged from 1.5 to 6.1 m s⁻¹. The corresponding Reynolds number range based on the nozzle gap and the mean velocity was 2200–8800. Constant heat-flux conditions were employed at the solid surface. Various impingement angles between the vertical planar jet and the inclined solid surface were investigated: 90° (normal collision), 70°, 60°, and 50°. In the case of normal collisions, the Nusselt number is high at the impingement line, and decreases with departures from it. The stagnation Nusselt numbers were compared to the predictions of several correlations proposed by other researchers. In oblique collisions, the profiles of the local Nusselt numbers are asymmetric. The locations of the peak Nusselt numbers do not coincide with the geometric center of the planar jet on the surface.