Moving surface boundary-layer control - Studies with bluff bodies and application

Unrestrained Cylinders Rolling in Steady Uniform Flows

“…The exact speed at which separation is completely suppressed was not determined, but the numerical results showed that even at terminal velocity ratio n = 0.6, the flow was not separating from the cylinder. The results verified expectations that separation would be suppressed based on the early work reported by Prandtl and Tietjens (1957) and Goldstein (1965), and the more recent work reported by Modi et al (1990Modi et al ( , 1991aModi et al ( , 1991b and Munshi et al (1996).…”

“…In more recent studies, Modi et al (1990Modi et al ( , 1991b showed how rotating cylinders at certain points along an airfoil controlled separation and resulted in increased lift and stall angles for the foil. Modi et al (1991a) investigated the flow past bluff bodies. They showed that the drag on a flat plate perpendicular to the flow could be reduced as much as 75% when rotating cylinders were placed on the upper and lower edges of the plate.…”

Control of Flow Past Bluff Bodies Using Rotating Control Cylinders

“…Some of them are the relative sizes of the main and control cylinders, their relative arrangements, and the rotation rates of the two control cylinders. Modi et al (1991aModi et al ( , b, 1992 have reported results for #ow control on blu! bodies for various rotation rates of the control cylinders.…”

“…He has reported the work carried out by Prandtl in 1907 who showed that by rotating a cylinder immersed in a stream of water he could prevent separation on the side advancing with the #uid. Modi et al (1991aModi et al ( , b, 1992 and Munshi et al (1997) have employed this concept to increase the maximum lift on airfoils and to reduce the drag on blu! bodies.…”

“…body and the control cylinder(s). Modi et al (1991aModi et al ( , b, 2000 and Modi (1997) applied MSBC to two-dimensional airfoils in the subcritical range of Reynolds number (Re"3;10!5;10) with various arrangements of the control cylinders. Laboratory experiments were conducted for various angles of attack and rotation speeds of the control cylinders.…”