An Experimental Study on Heat Transfer Characteristics of a Cam-Shaped Tube with Different Aspect Ratios in Cross Flow

In this paper, the heat transfer characteristics of a cam-shaped tube with aspect ratios from L/D=1.35 to 3.74 in the crossflow of air have been experimentally investigated for two angles of attack, 0o and 180o. The Reynolds number varies in the range of 20000 to 46000 based on the equivalent diameter of a circular tube. One can conclude from the results that the best thermal performance was for L/D=1.35 at 180 degrees. The mean Nusselt number for this tube is 11% higher than that of a circular tube with equivalent diameter. For this tube, when the Reynolds number is 20695, the mean Nusselt number is 19.4% higher than that of a circular tube with equivalent diameter. And the lowest mean Nusselt number was recorded for the tube with L/D=3.74 at zero angle of attack. The mean Nusselt number for this tube is 21% lower than that of a circular tube with equivalent diameter.