An experimental investigation of the vortex-excited vibrations of pivoted tapered circular cylinders in uniform and shear flow

A systematic experimental investigation to understand the effect of flow an d structural nonuniformity on vortex-excited vibrations is underway at the University of Notre Dame's Hessert Center for Aerospace Research. The exper iments are designed to investigate the effects of axial taper of a circular cylinder and its interaction with shear in the approach flow on the struct ural response to vortex shedding. The dynamic response characteristics of a pivoted, tapered circular cylinder subjected to vortex-excited vibrations in a wind tunnel are reported here. In all, six scenarios of tapered pivote d cylinders in uniform and shear flows were investigated. The salient featu res of the experimental investigations and the experimental observations ar e presented here as time histories of the structural displacements, structu ral response amplitudes as a function of flow speed and power spectral dens ities of the near wake velocity fluctuations. The results of the experiment al investigations indicate that the response of axially varying structures to vortex-excited vibrations is quite different from those of uniform cylin ders (Balasubramanian et al., J. Fluids. Struct. 14 (2000) 65). The range o f locked-in structural response is found to be very sensitive to the relati ve orientation between the flow-gradient and axial taper of the cylinder. ( C) 2001 Elsevier Science Ltd. All rights reserved.