Aspects of the flow in the immediate vicinity of a porous shroud

Abstract This note presents the results of a flow-visualisation study of three successful porous shrouds designed for the suppression of vortex-excited vibration. The results clearly show that, although significant detailed differences do exist, the salient features of the streak patterns in the immediate vicinity of each shroud are similar, thus confirming the previous speculations of Galbraith [1] regarding such flow patterns.