Prediction of heat transfer from impinging knife-jets using a dynamic subgrid stress model

Abstract

The turbulent flow field and heat transfer due to the knife-jets impinging on a flat surface have been numerically investigated. The large-eddy simulation (LES) technique has been used to model the turbulent flow that has both large- and small-scale structures. A dynamic subgrid scale model has been used to account for the subgrid scale stresses and heat transfer. The Nusselt number distributions for the impinging jets emanating from an array of horizontal slot nozzles are presented within the Reynolds number range of 600-3000. Two different jet exit-angles, namely 0° and 60° have been considered. The reattachment of the horizontal-knife-jets is obtained due to the Coanda effect. The flow field on the impinging plate due to the horizontal-knife-jets culminates in an oscillatory flow dominated by vortical motions. Such motions play a significant role in enhancing heat transfer. Heat transfer due to the horizontal-knife-jet with 60° exit-angle has been found to be greater than that of the axial slot jet.