Heat transfer from an isothermally heated flat surface due to twin oblique slot-jet impingement

Impinging jets are used for quick and efficient cooling of heated surfaces. For normally impinging jets, one shortcoming is that high heat transfer is achieved only around the impingement region of the heated surface while the remaining parts of the surface under the wall jet region is subjected to significantly lower heat transfer rate. In order to achieve a more distributed heat transfer along an extended heated surface, the use of twin oblique impinging jets separated by a distance is proposed. In this study, convective heat transfer from a heated flat surface due to twin oblique laminar slot-jet impingement is investigated numerically. The flow domain is confined by an adiabatic surface parallel to the heated impingement surface. The twin slot jets are located on the confining surface. The flow and geometric parameters are the jet exit Reynolds number, distance between the two jets, distance between the jet exit and the impingement surface, and the inclination angle of the jet to the impingement surface. Numerical computations are done for various combinations of these parameters and the results are presented in terms of the streamlines and isotherms in the flow domain, the distribution of the local Nusselt number along the heated surface, and the average Nusselt number at the heated surface. It is found that for impingement angles up to 60 degrees, the heat transfer is not desirably distributed. However, at 45 degrees impingement angle, heat transfer is reasonably distributed with a corresponding decrease of about 36% overall heat transfer. (C) 2013 The Authors, Published by Elsevier Ltd.