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AHMED N A
School of Mechanical and Manufacturing
Engineering,
University of New South Wales,
Sydney 2052, Australia |
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INVESTIGATION OF
DOMINANT
FREQU-ENCIES IN TRANSITION
REYNOLDS NUMBER RANGE OF
FLOW AROUND
A CIRCULAR CYLINDER
PART I: EXPERIMENTAL STUDY OF
THE RELATION BETWEEN VORTEX SHEDDING AND
TRANSITION FREQUENCIES
Abstract:
A comprehensive hot wire investigation of the flow around a circular cylinder is carried out in an 18" ´ 18" wind tunnel to look into the dominant frequencies at the stagnation, separation and separated shear layers in the transition Reynolds number range. The majority of the experiments are carried out at Reynolds number of 4.5 ´104, with additional transition frequency tests at Reynolds numbers of 2.9 ´ 104, 3.3 ´ 104 and 9.7 ´ 104 respectively. The results are analysed in terms of power spectral density. While the frequency associated with stagnation is found to be essentially due to vortex shedding, frequency doubling of vortex shedding is also evident in the separated shear layers. Two peaks associated with transition frequencies are detected and their possible implications are presented.
Key words:
Vortex shedding Transition Separated flow Power spectral density |