Session Ce - Separated Flows.
ORAL session, Sunday, November 23
305, Moscone Center
An experimental study of the vortex-induced vibrations of pivoted cylinders was conducted to investigate the lock-in behavior between vortex shedding and body vibration for Reynolds number ranges from 16,500 to 22,000. Several scenarios were investigated including circular and tapered cylinders in both uniform and shear flows. Each case consisted of a rigid cylinder pivoted at one end with a bearing and stiffened by two transverse springs at the other. The cylinders were allowed to oscillate only in the cross-flow direction. The lock-in region was traversed by varying the flow velocity. An optical system was used to measure cylinder displacement while a hot wire was used to measure wake velocity oscillations. Measurements of interest included the response amplitude, the displacement time series, the width of the frequency lock-in range, and power spectral densities of the wake shedding for different Re numbers and spanwise positions. A comparison between the results for different flow and pivoted body configurations reveals significant changes in the range of lock-in.