Characteristics of Periodic Vortex Shedding From Two Cylinders in Cruciform Arrangement

✍ Scribed by M. Shirakashi; H.M. Bae; M. Sano; T. Takahashi

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 607 KB
• Volume: 8
• Category: Article
• ISSN: 0889-9746
• DOI: 10.1006/jfls.1994.1012

✦ Synopsis

In earlier papers, the authors reported a new vortex excitation of a circular cylinder induced by another set downstream in a cruciform arrangement with a gap smaller than half the cylinder diameter. In this work, the structure of the flow causing this excitation is investigated through measurements of velocity and pressure on the cylinder surface, together with flow visualization. When the gap-to-diameter ratio, (s / d<0 \cdot 5), the flow near the crossing of the cylinders is dominated by one of two types of three-dimensional vortices: trailing vortices and "necklace vortices". When (s / d=0-0 \cdot 25), the trailing vortices are shed periodically and generate excitation on the upstream cylinder. When (s / d=0 \cdot 25-) (0 \cdot 5), the necklace vortices are formed periodically around the downstream cylinder and cause an alternating lift force on the upstream cylinder. The shedding frequencies of these two kinds of vortices differ by a factor of around 2. This fact results in a discontinuity at (s / d=0.25) in the curve representing the relationship between the reduced resonant velocity and (s / d) for an elastically supported system.