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.

Boiling induced atomization appeared in the liquid film by wall impinging jet on the superheated wall

“…2(b)). As reported in many research [1][2][3][4], nucleate, transition and film boiling coexist in the liquid film during the quenching, and the droplets in Fig. 2 were considered to be caused by these boiling phenomena.…”

“…Impinging jet cooling technique is widely used in the industrial fields such as material processing [1][2] [3], cooling of nuclear reactor cores [4] [5], bipropellant propulsion systems [6] [7] and many more. In this cooling technique, liquid films are formed on the wall whose temperature exceeds the saturated temperature or the Leidenfrost temperature of the coolant.…”