周期的かく乱に対する乱流はく離泡の応答 : 強いかく乱に対する応答およびせん断層の構造変化

概要

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The leading-edge separation bubble of a blunt circular cylinder aligned with the main flow was forced by a single-frequency sinusoidal disturbance at a Reynolds number of 6.9×10^4. The amplitude of the forcing was varied from 0.5% to 20% of the main-flow velocity. At forcing amplitudes of less than 10%, the reattachment length attained a minimum at a particular forcing frequency. At higher amplitudes, greater than 14%, the separation bubble was almost eliminated over a range of forcing frequencies. The stronger the disturbance, the wider the range of forcing frequencies where the separation bubble was eliminated. The change in vortex structure in the separated shear layer by the forcing was determined from the distribution of the time-mean and rms velocities, the evolution of the power spectrum of the pressure fluctuation at the center of the shear layer, and the smoke-wire flow visualization at a lower Reynolds number of 1.4×10^4. A model was presented to explain the forcing frequency at which the reattachment length attained the minimum.
社団法人日本機械学会の論文
1995-06-25