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標題: Lock-on of vortex shedding due to rotational oscillations of a flat plate in a uniform stream
作者: Chen, J.M.
Fang, Y.C.
關鍵字: circular-cylinder;flow structure;bluff-bodies;wake;line
Project: Journal of Fluids and Structures
期刊/報告no:: Journal of Fluids and Structures, Volume 12, Issue 6, Page(s) 779-798.
The lock-on of vortex shedding induced by rotational oscillations of a flat plate normal to a uniform stream in its neutral position has been studied experimentally for Reynolds numbers in the range Re = 3000-8000. The onset of lock-on, which depends on the combination of the frequency and amplitude of the forcing, is examined by using spectral analysis of the wake velocity. The forcing frequency is set to a fixed value, between 80 and 120% of the natural shedding frequency of the stationary normal flat plate, while the angular forcing amplitude is varied to search for the lock-on regime. The lock-on regime is found to become narrower with increasing free-stream velocity. Effects of blockage on the lock-on regime are also investigated in some detail. For vortex locking-on to the frequency of the forcing above or below the natural shedding frequency, significant differences are observed in the distributions of fluctuating and time-mean base pressures. Flow visualization suggests that these differences are primarily due to the formation of shed vortices. (C) 1998 Academic Press.
ISSN: 0889-9746
DOI: 10.1006/jfls.1998.0164
Appears in Collections:機械工程學系所

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