| 摘要 |
To modify a turbulent boundary layer flow over a surface to reduce its drag, a series of streamwise riblet projections is provided on the surface. These are arranged in a repeated spanwise pattern in which the adjacent projections in each pattern repeat project to different heights. The different heights are so scaled in relation to each ther and to the boundary layer thickness that the displacement of the turbulent motion away from the surface by the smaller height projections is extended further by the larger height projections. The effective area of activity of the projections is thereby continued over a greater stream development length. |
