On the cooling effect of an air jet along the surface of a cylinder

Heat transfer of slot jets of air impinging on the surface of a circular cy linder by forced convection has been investigated. The cylinder has a diame ter of D=10 mm and the slot jet has a height of S=5 mm. The thermocouples, located along the surface of the cylinder, at various angles from the impin ging point, allow the evaluation of the local convective heat transfer coef ficients. The experiments have been performed for a Reynolds number of the impinging air ranging from Re=4000 to Re=20000. The influence of the distan ce H, between the exit of the slot jet and the cylinder, has been investiga ted in the range of H/S, H/S=2-10. The local Nusselt number is a function o f the WS ratio and of the angle from the front impinging point. It is also dependent on the Reynolds number. (C) 2000 Elsevier Science Ltd.