摘要

Two-component velocity measurements were made with laser Doppler velocimetry in the near wake of a freely vibrating, elastically mounted, light weight circular cylinder at lock-in. Maximum cylinder displacements of 0.75d were observed for a mechanical damping level of about 0.2% of critical. The Scruton number was 1.5, while the Reynolds number at lock-in was about 53,000. The velocity data were phase averaged relative to the periodic loading cycle. Significant differences in the details of the turbulence when the cylinder is oscillating compared to the stationary case were observed. These differences lead to increased production of incoherent turbulence. Interestingly, the wake of the oscillating cylinder is narrower than that for the stationary cylinder, so that less engulfment has occurred in spite of the increased strength of the main vortices. This is attributed to the reduced three-dimensionality during formation, in particular, the mitigation of oblique shedding and vortex dislocations.