Experimental validation of numerical heat transfer models of an impingement jet at high Reynolds numbers

Abstract

In industrial thermal processing plants, metal strips are quenched in cooling zones by impingement jets, with convection being the dominant heat transfer mechanism. To generate the impingement jets, gas is accelerated through a nozzle system and directed onto the material surface, resulting in rapid and uniform cooling. The present work involves the experimental investigation of the heat transfer and associated flow of impingement jets using PIV on a single slot (W = 5 mm) and a single round nozzle (D = 25 mm). These experimental methods form the basis for the evaluation of numerical turbulence models. The turbulence models selected in this work are: SST k-ω model, Generalised k-ω (GEKO) model and the Reynolds Stress Model. The investigations are carried out at a nozzle exit velocity of u ≈ 51 m/s (Re_Slot = 34,490, Re_Round = 88.780). Compared to other studies with a Reynolds number of below 23,000, the prediction accuracy is less due to the high Reynolds number. The PIV measurement shows that the flow velocities are correctly modelled, but the turbulent kinetic energy can only be poorly predicted.^{[email protected]}