Modification of the Karman-vortex street in the freestream

An experimental study conducted in the NASA Langley 15-in Low-Turbulence Wind Tunnel demonstrated that a relatively short-chord flow-aligned plate placed in the proximity of a cylindar could produce nearly one-signed oscillatory transverse control vortices. Typical results showed the screen with the 40 mesh to have a solidity of 35 percent, and the screen with 57 mesh to have a solidity of 35 percent, and the screen with 57 mesh to have a solidity of 72 percent. In all cases, the turbulence level of the incoming freestream was seen to have little effect on the suppression of the shed vorticity within the range considered.