Effect of Tripping Wires on the Flow around a Circular Cylinder Normal to an Airstream

TLDR: In this article, the effect of tripping wires on the transition in a boundary layer on a circular cylinder in a cross flow was investigated and it was shown that the roughness has no influence on transition up to Rek =620, while, at Rek≥1220, it has full effect on transition.

Abstract: Experimental studies have been made to make clear the effect of tripping wires on the transition in a boundary layer on a circular cylinder in a cross flow. The flow patterns are variable according to the angle φR, namely, a contact point of the tangent to the cylinder from the top of the roughness, and to the roughness Reynolds number Rek, defined by the roughness height and the velocity at the outer edge of the boundary layer. In the range of φR < 70°, the roughness has no influence on the transition up to Rek =620, while, at Rek≥1220, it is found to has full effect on the transition. In this case, the Strouhal number S increases to 0.30 and the drag coefficient CD decreases to 0.60. In the range of 70°≤φR≤75°, the transition occurs at Rek = 620. Beyond φR =76°, the flow is separated by the roughness, and the values of S and CD are about 0.175 and 1.55, respectively.