The angle of attack effect on thermal-hydraulic performance of a cam-shaped tube with constant heat flux in crossflow

An experimental study was performed to determine the effect of angle of attack on the thermal-hydraulic performance of a cam-shaped tube with constant heat flux in crossflow. The Reynolds number based on an equivalent diameter was in the range of 15500 < Re-Deq< 42000, and the angle of attack (alpha) varied from 0 degrees to 180 degrees. For the heat transfer experiments, five different heat fluxes were considered, and the results showed that in all Reynolds numbers by increasing the angle of attack, the mean Nusselt number increases about 1-6% at alpha = 30 degrees, 3-9% at alpha = 60 degrees and 5-11% at alpha = 90 degrees compared to the Nusselt number at alpha = 0 degrees. Besides, the drag coefficient for these angles increased 40-53%, 105-109% and 114-122%, respectively compared to alpha = 0 degrees. In all Reynolds numbers, alpha = 0 degrees and 150 degrees had the lowest drag coefficient, which was 29-55% and 27-56% lower than other angles of attack. Also, the best thermal-hydraulic performance was achieved at alpha = 0 degrees and 150 degrees.