Determination of rewetting on hot horizontal surface with water jet impingement through a sharp edge nozzle

Abstract

The rewetting phenomenon was experimentally investigated for the hot horizontal stainless steel surface of 0.25 mm thickness and 800 ± 10 °C initial surface temperature. The round water jet of 2.5 mm diameter at 22 ± 1 °C temperature was injected through a sharp edge nozzle. The investigation was done for the stagnation point to 12 mm (≈5d) radial distance and jet Reynolds number varied in the range of 5000–24,000. The rewetting phenomena during the transient cooling was accessed on the basis of rewetting temperature, wetting delay, wetting speed and maximum surface heat flux.It has been observed that with rise in jet Reynolds number, the rewetting performance increased for the entire measured spatial locations. However, for downstream region the surface rewetting has been delayed and occurred at the reduced surface temperature as compared to the stagnation region. The maximum surface heat flux is the highest at the stagnation point and in a range of 2.1–2.45 MW/m2. The correlation developed for the wetting front speed predicts 85 percent of experimental data within an error band of ±20 percent and the correlation for maximum surface heat flux predicts 90 percent of experimental data within an error band of ±10 percent.