Drag Reduction by Boundary Layer Control With Passively Moving Wall

There exists a wide range of approaches to reduce the skin friction drag. One of the approaches is to attenuate the no-slip condition by moving the wall in flow direction. This reduces the velocity difference between the mean flow and the wall and thereby the wall shear stress. Actively moving walls are used for nearly all known investigations on this topic. This paper presents a concept for a passive moving wall. The motion of the wall is driven by the wall shear stress itself. For this investigation the moving wall is designed as a rotating disc which is embedded in the surface of a flat plate. One half of the disc is covered, whereas the other part is exposed to the flow. The interaction between the rotating disc and the flow is investigated experimentally by means of flatted Pitot probe measurements and rotation speed measurements.