IMPINGING JET COOLING OF HOT HORIZONTAL CYLINDERS

Abstract

An Experimental analysis has been carried out on jet impingement cooling of hot horizontal stainless steel (SS-316) rod by a jet with diameter of 2.5 mm. Initially, the rod was heated upto a temperature of 800 ± 10°C and was impinged on its surface by a round water jet of temperature 23 ± 1°C, which is injected by a sharp edged nozzle. The jet was made to impinge orthogonally on to the rod surface. The jet Reynolds number was varied from 5000-24000 and the temperatures were measured up to a distance of 9 mm axially from the stagnation point. The effects on the cooling behavior of the test rod, at the stagnation point and various axial locations, due to variation in Reynolds number have been studied. Moreover, the rewetting phenomenon was studied by evaluating the rewetting parameters viz. rewetting temperature, wetting front speed, wetting delay and, maximum surface heat flux. The cooling is found to be enhanced by increase in Reynolds number. For downstream locations the cooling is delayed and occurs at reduce temperatures. A correlation has been developed from the experimental data to determine wetting front speed in dimensionless form, which predicted 93% of the experimental data within an error band of ±20%.