Photographic Evidence of the Mechanisms of Vortex-Excited Vibration

Abstract

The mechanism of vortex-excited vibration of a cylindrical structure in the cross-flow of a fluid has been understood for some time. Several actual cases have been reported for structures such as chimneys, bridge towers, submarine periscopes, etc., and the phenomenon predicted by model experiments. The author considers that direct photographic evidence of the details of the basic process to be necessary for instructional purposes. The paper describes some flow visualization experiments designed to produce the required evidence, and presents the results.

The investigation reported here covers the often reported vibration of structures at right angles to the flow direction and deals also with more unusual modes of vibration which were photographed by three different techniques. A carefully arranged photographic and visualization technique was also used to demonstrate that the vibrating structure moves away from the shed vortex.

Notes

Paper presented at a symposium on “Photography as a Visualization Tool”, organized by the Scientific and Technical Group of The Royal Photographic Society on 6-7 April 1978 at 14 South Audley Street, London W1Y 5DP