Modified Circular Cylinder Fin

Abstract

In this work the influence of bores along circular cylinder and its rotation with respect to free stream on heat transfer rate was carried out experimentally. Three types of hollow cylinder were presented. The first one is hollow with inside diameter 15.3 mm and outside diameter 23mm. While, both the second and third cylinders have the same inside and outside diameter and provided two bores for each one with diameters 6.3 mm for the second cylinder  and 7.6mm for the third one. The second and third cylinders rotate with respect to free stream at angles of (0^o, 30^o and 60^o). The free stream behaviors were observed using the smoke wind tunnel incense. Moreover, the periodic heat source was applied on these three cylinders and the temperature distributions were measured using digital thermometer. Three magnitudes of air flow velocities were presented (1.4 m/s, 1.7 m/s and 2.45 m/s) in experimental work. ANSYS software was used to predict the pressure and velocity distribution adhere the cylinder wall at maximum flow velocity (2.45 m/s). These distributions of pressure and velocity recognize the separation angles and benefit to reveal the residual mass flow inside the hollow puncher cylinder for each step. Also, the separation angles that detected depend on ANSYS program was used to quantify the average Nusselt number. The results show that the bores will increase the heat transfer dispersion especially at rotation angle 30^o. Moreover, the amount of residual mass flow inside the hollow puncher cylinder is the important parameter that used to increase the efficiency of heat dissipation. Besides, the bore with cylinder rotation angle larger than 0^o help to prevent boundary layer to be separated and kept longer attaches.

Keywords: circular cylinder, holes, separation flow, heat transfer, convection, ANSYS simulation.