Effect of Riblets on Flow Separation from a Cylinder and an Airfoil in Subsonic Flow.

摘要

The thesis investigated the effect of riblets on flow separation from a cylinder and an airfoil in subsonic flow. Riblets have been used successfully to reduce viscous drag on a flat plate and significantly delay flow separation in a two-dimensional, straight-walled, subsonic diffuser. The investigation indicated that for a 2-D cylinder model, the separation point could be delayed as much as 5.5 percent by applying riblets to the model surface. Minor delays in separation were also achieved by applying riblets to a 2-D airfoil model at 8 and 12 deg angle of attack. Applying riblets to the cylinder and airfoil models consistently altered the pressure distribution compared to the same models without riblets. In comparing the cylinder and airfoil results with those of the subsonic diffuser, it appears that riblets are most effective in delaying flow separation in relatively weak adverse pressure gradients. Cylindrical bodies. Theses. (edc)