Trapping vortices is a new technology used on wings to prevent vortex shedding and reduce drag in flows past bluff bodies. It is a promising technology that will push the new generation of wings to the next level. An experimental investigation focusing on the effect of three different type of cavities on wing aerodynamic properties are performed at three different Reynolds number varying from 1.0×105 to 3.0×105. The study is performed using the wind tunnel facility owned by Universiti Sains Malaysia (USM). Results suggest that the experimental data comparisons are in good agreement with the data obtained from prior studies. The pattern of experimental data plots against angle of attack are in relative similarity with the general pattern. The results indicate that the load data measured by the wind tunnel facility are more consistent when the experiments are performed at higher Reynolds number, 2.0×105 and 3.0×105 compared to Reynolds number 1.0×105. It is believed that the discrepancies are most likely due to significant electromagnetic interference (EMI) effect in the internal force balance at low Reynolds number. As for comparisons of wing models with and without cavity, at low Reynolds number of 1.0×105, the wing model with circular cavity has the highest lift curves; however, at higher Reynolds number, 2.0×105 and 3.0×105, the standard wing model has the highest lift coefficient curves compared to the rest. As for the drag comparison for all wing models, at Reynolds number 1.0×105, all wing models with cavity have lower drags than that of standard wing model. At higher Reynolds number 2.0×105 and 3.0×105, the drag curves for all wing models coincide with each other. Based on the wind tunnel aerodynamic load data collected, the results of circular cavity shape suggest that it has successfully trapped the vortex with increment in lift and reduction in drag at Reynolds number 1.0×105. At this Reynolds number, the circular cavity optimally traps vortex and prevents vortex shedding at the trailing edge of the wing. The flow is smoother, more laminar, and remains attached on the surface of the wing model, which primarily leads to the increment in lift and reduction in drag.
The effect of cavity shapes on vortex trapping_Tan Kiu Leong_A2_2014_NI