外部音波による円形噴流せん断層のかく乱への影響(流体工学,流体機械)

概要

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This paper examines the effect of sound on the disturbance in the shear layer of a round jet with at a range of sound frequencies, from 200 Hz to 1000 Hz at intervals of 100 Hz using pure tones and recordings of machines operating at different frequencies. Hot-wire velocity measurements, FFT analysis and flow visualization were used to reveal the shear layer structure. Since round jets are used in industrial applications, their environments are generally noisy, thus it is important to understand how the frequency of background sounds affect shear layer disturbance. When the frequency was varied the maximum disturbance was observed at 500 Hz, which coincides with the predominant frequency of a free jet. Spectral components in harmonics arose via nonlinear interaction as the disturbance moved downstream, and transition from laminar flow to turbulent flow progressed through vortex pairing and collapse. Pure tone and machine generated sound exhibited similar characteristics.
社団法人日本機械学会の論文
2007-08-25