Effect of Shroud Hole on the Force Characteristics of a Circular Cylinder

Abstract

Characteristics of flow pass a shrouded cylinder were investigated experimentally using uniform and non-uniform hole shrouds. The experiments were performed to compare the effect of hole-uniformity of the perforated shroud on the cylinder lift and drag. The porosity for uniform hole shrouds in triangular and square configurations were set around 0.30, while that for non-uniform hole shrouds were set from 0.25 to 0.37. The diameter ratio between the shroud and the bare cylinder was set at 2.0. The experiment was performed in a wind tunnel at Reynolds Number of 9.345 x 103 based on the bare cylinder diameter and constant incoming air flow speed. Results showed that although all shrouded cylinder models reduced drag significantly in comparison to that of the bare cylinder case, the non-uniform hole shrouds were considerably effective than the uniform hole shrouds. Total drag reduction achieved by the non-uniform hole shrouds of 30% porosity was between 90-95% whereas that of uniform hole was only 55-80% at the same porosity.

Effect of Cylinder Gap Ratio on The Wake of a Circular Cylinder Enclosed by Various Perforated Shrouds

“…They discovered that a shrouded cylinder reduced the vortex-induced oscillating lift forces. Experiments conducted by Osrin et al, [10] on the effect of shroud hole uniformity on a circular cylinder wake showed that, although all shrouded cylinder models reduced drag significantly in comparison to that of the bare cylinder case, the non-uniform hole shrouds were considerably effective than those of uniform hole shrouds. Misman et al, [11] discovered that simply changing the slot profile can prevent vortex shedding along the structure's length and wake vortices' formation.…”

Vane Angle Influence on the Flow Pattern around a Circular Pier

“…According to their results, the use of a special device reduced the scour depth around the pier. Osrin et al (2019) experimentally investigated the flow pattern past the shrouded cylinder. Their work revealed the impact of perforated shrouds' uniform and non-uniform holes on the cylinder's drag and lift coefficients.…”