Determining the local value of heat transfer coefficient (HTC) on a surface cooled by an axisymmetric water jet

This paper presents the experimental findings of cooling an EN 1.4828 steel plate with a single water jet, and the results of computing the local heat transfer coefficient (HTC) and heat flux (HF) on the plate surface cooled. The plate cool from an initial temperature of 906 °C. The plate temperature measure 2 mm under the surface cooled, using 48 sheathed thermocouples 0.5 mm in diameter. Three-dimensional inverse solutions yielded HTC and HF as a function of surface coordinates and time. The uncertainty of the measured values and the resulting uncertainty of the calculated heat transfer coefficient were determined. Temperature distribution predict by the model is compared to the data obtained from measurements. Results allow to formulate an equation of local HTC as a function of non-dimensional temperature and the non-dimensional ratio of the distance to the stagnation point to the nozzle diameter. According to the author's knowledge, this work fills a gap in the literature by providing relationship describing local HTC as a function of surface temperature and distance from the stagnation point in the case of single water jet cooling with unsteady heat transfer.