Effect of Active Flow Control Mechanisms on the Turbulent Flow Structures

Blowing or suction on the wall is expected to efficiently control the characteristics of wall-bounded turbulent flow such as wall-frictional coefficient. To understand the mechanism of the change of turbulence statistics caused by this method, we experimentally investigated the effect of uniformly blowing and suction flow on a turbulent structure in a relatively simple flow, fully developed turbulent channel flow. For blowing, the friction coefficient and the thickness of the low-speed region increased. These results imply that the boundary layer becomes unstable because the growth of viscous sublayer is rapid and the time-scale of reaching a critical thickness is small due to the blowing from the wall. On the other hand, for suction, the opposite tendency appeared.