Long-duration time-resolved PIV to study unsteady aerodynamics

A time-resolved particle image velocimetry (PIV) system has been developed at the University of Western Ontario, London, ON, Canada, with long-recording-time capabilities. This system is uniquely suited to the study of unsteady aerodynamics and hydrodynamics, such as avian aerodynamics or bluff-body oscillations. Measurements have been made on an elongated bluff body through the initial build-up phase of flutter. The possibilities to study this instability, which was responsible for the collapse of the Tacoma Narrows Bridge, are significantly broadened by the use of this system. The long-time recording capability of the system allows for novel results since it yields data that are spatially and temporally resolved over a long record length. The buildup of flutter is shown to exhibit complex dynamics that are heavily influenced by the flow-induced motion of the body. Features of the wake turbulence as a function of time are presented and shown to substantially vary.