Effect of Jet Inclination and Coolant Flow Rate on Thermal and Rewetting Behavior during Bottom Jet Impingement on Hot Horizontal Surfaces

Abstract

The thermal and rewetting behavior of downward-facing hot surfaces with single upward oblique liquid jet impingement is studied through experimental investigation. The Reynolds number varies in the range of 2500–10 000 and the jet inclination angle varies from 90° to 15°, measured from the horizontal. The current study uses a stainless-steel foil (SS-304) with 0.15 mm thickness as the test specimen, and a thermal imaging technique is used to measure temperature data during jet impingement cooling. The initial surface temperature of the test foil is maintained at 500 ± 10 °C and the standoff distance is kept at 6 mm. The Nusselt number is found to increase in the downhill direction and decrease sharply in the uphill direction with the decrease in the inclination angle. The wet-front velocity is found to increase in the downhill direction with the decrease in the inclination angle. Correlations are proposed for Nusselt number and rewetting temperature as a function of Reynolds number, jet inclination angle, and axial distance. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim