On Drag Reduction Effect of Contour Bump of Supercritical Airfoil

The effect of contour bumps on transonic drag reducing at off-design conditions of a supercritical airfoil have been examined in the paper. Research focuses on two-dimensional flow condition with Mach number of 0.78 and chord Reynolds number of 2.5 million. Different contour bump airfoil configurations are examined using numerical method. Recent tests on these models are conducted in 0.6m×0.6m transonic wind tunnel at CARDC to validate the drag reduction effect. The computational results indicate that a surface contour bump is capable of reducing transonic drag for moderate to high lift conditions, but raises the drag remarkably for lower lift condition due to the second shock wave generated near the aft of the bump. The experimental research shows a good agreement with the computational. With the computational and experimental evidences, the mechanism of contour bump's effect on transonic drag reduction has been further analyzed.