Management of Two-Dimensional Channel Flow with a Pair of Streamwise Vortices

(Behavior of Streamwise Vortices and Mean Velocity Field)

抄録

An experimental study was conducted to examine the management of a two-dimensional turbulent channel flow with a pair of streamwise vortices. A common-flow down type streamwise vortex pair, generated by a pair of half-delta wings mounted on the wall, was introduced into a fully developed turbulent channel flow. The half-delta wings were as high as the inner layer thickness of the channel flow. The mean velocity and Reynolds shear stress distributions were measured and various properties were obtained in order to find meanings of the vortex generator for management of the turbulent channel flow. The convective motion of the secondary current is responsible for most of the streamwise momentum transfer toward the wall in the interaction between the vortices and the shear layer. In the velocity profile averaged over the spanwise extent, the velocity is accelerated below the vortex center and decelerated above the vortex center. Deformation of the mean velocity profile remained at the remarkable downstream distance of 250 times the wing height, which corresponds to 50 times channel the half-width H.