Effect of Winglet Shape on Heat Transfer from Heated Cylinder in Cross Flow

Abstract

Experimental investigation of the flow and heat transfer around a heated cylinder in cross flow with and without using winglets has been carried out. Distribution of the static pressure coefficients and Nusselt number and knowledge of the flow processes around the cylinder without winglets enable as to form an idea of the mechanism and pattern of the flow around the cylinder with winglets. The flow was in fully-developed turbulent flow with Reynolds number range 0.72*10 4 ≤Re≤1.44*10 4 . Four different shapes of winglets were used with different angles of attack (20, 26, 32) at different locations ((Xm/D=0, 0.17, 0.3, 0.5), (Ym/D=0.57, 0.65, 0.72, 0.8)). The results show that there is an effect of winglet shapes on heat transfer and pressure drop, and a better shape is a (trapezoidal (type 3)). For enhanced heat transfer from cylinder, heat transfer increases with increasing Reynolds number and angle of attack. Also the results show that the optimum position of winglet for enhanced heat transfer is (Xm/D=0.17 and Ym/D=0.65). The research shows that heat transfer is enhanced as high as (14%) when winglets are used when compared with the case of a cylinder without winglets. There is also a slight increase in pressure drop.