Slot jet impingement heat transfer from an isothermal circular cylinder

Abstract

The heat transfer characteristics of a circular cylinder exposed to a slot jet impingement of air has been studied experimentally. The study focused on low Reynolds numbers ranging from 120 to 1210 and slot-to-cylinder spacing from 2 to 8 of the slot width. A Mach-Zehnder interferometer was used in the experimental study. Local Nusselt numbers at cylinder surface were obtained using infinite fringe mode which corresponds directly to isotherms in the flow field. It has shown that the local Nusselt number has a maximum value at the stagnation point and then decreases to a minimum distance between isotherms. It is observed that slot jet impingement has a great effect on the local heat transfer coefficient from the stagnation point to the angle of 120deg and local Nusselt number at the downstream is approximately similar to the case of free convection for the low and moderate Reynolds numbers. In addition, increasing the distance between nozzle and cylinder decreases average heat transfer coefficients. In order to check the accuracy of the experiment and method of data reduction first the case of free convection was tested and the results were compared with the previous works which has an excellent agreement.