Hostname: page-component-76fb5796d-45l2p Total loading time: 0 Render date: 2024-04-26T08:16:29.526Z Has data issue: false hasContentIssue false
  • English
  • Français

A lock-in effect in the flowover two cylinders

Published online by Cambridge University Press:  04 July 2016

F. H. Barnes ,
A. J. Baxendale  and
I. Grant
Get access Rights & Permissions [Opens in a new window]

Summary

Measurements are presented of the frequency of vortex shedding from two circular cylinders in a staggered arrangement. Seven different cylinders were used in turn as the upstream cylinder and the ratio of the diameter of the upstream cylinder to that of the downstream cylinder ranged from 0·00422 to 0·571. For a constant free-stream velocity changing the upstream cylinder changed the frequency of vortex shedding from the cylinder. It was found that the frequency of vortex shedding from the downstream cylinder N synchronised with that of the upstream cylinder n over a range of the latter frequency. When the frequencies were synchronised the ratio of the frequencies was given by n/N = 2. This behaviour is characteristic of a lock-in process.

Lock-in was found at each of the four upstream cylinder positions tried. However, it was only when the upstream cylinder position was such that the upstream cylinder only weakly affected the flow about the downstream cylinder that lock-in was accompanied by a decrease in the base pressure. The time-mean drag force then increased with lock-in, but by a small amount only. On the other hand the fluctuating lift force increased substantially.

Type
Research Article
Information
The Aeronautical Journal , Volume 90 , Issue 894 , April 1986 , pp. 128 - 138
Copyright
Copyright © Royal Aeronautical Society 1986 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

*

Department of Physics, University of Edinburgh, Edinburgh.

†

Department of Offshore Engineering, Heriot-Watt University, Edinburgh.

References

1. Armstrong, B. J., Barnes, F.H. and Grant, I. The effect of a perturbation on the flow over a bluff cylinder. 1986 a. To be published in Phys Fluids. Google Scholar
2. Armstrong, B. J., Barnes, F. H. and Grant, I. A comparison of the structure of the wake behind a circular cylinder in a steady flow with that in a perturbed flow. 1985 b. Submitted for publication.Google Scholar
3. Baxendale, A. J., Grant, I. and Barnes, F. H. The flow past two cylinders having different diameters. The Aeronautical Journal, April 1985, 89, 884, 125–134.Google Scholar
4. Bearman, P. W. Vortex shedding from oscillating bluff bodies. Ann Rev Fluid Mech, 1984, 16, 195 Google Scholar
5. Davies, M. E. A comparison of the wake structure of a stationary and oscillating bluff body, using a conditional averaging technique. J Fluid Mech, 1976, 75, 209 Google Scholar
6. Griffin, O. M. and Ramberg, S. E. Vortex shedding from a cylinder vibrating in line with an incident uniform flow. J Fluid Mech. 1976. 75, 257.Google Scholar
7. McGregor, D. M. An experimental investigation of the oscillating pressures on a circular cylinder in a fluid stream. Inst Aerophysics, 1957, Univ Toronto UTIA Tech Note No 14.Google Scholar
8. West, G. S. and Apelt, C. J. The effect of tunnel blockage and aspect ratio on the mean flow past a circular cylinder with Reynolds numbers between 104 and 105 . J Fluid Mech. 1982, 114, 361.Google Scholar
9. Zdravkovich, M. M. Review of flow interference between two circular cylinders in various arrangements. J Fluids Eng. 1977, 99, 618.Google Scholar