This paper presents experimental results concerning the response of circular cylinders with and without strakes. The longitudinal and transverse fluid forces (drag and lift), amplitude response and wake structures of plain and helically straked cylinders are compared. Six different configurations of straked cylinders with pitches (p) equal to 5D, 10D and 15D and heights (h) equal to 0.1D and 0.2D are investigated. Measurements on the dynamic response oscillations of an isolated plain and straked cylinders and flow visualization employing a PIV system are shown. Fixed cylinder drag measurements are also shown. The models are mounted on an elastic base fitted with flexor blades and instrumented with strain gauges or in an air bearing base. The base is fixed on the test-section of a water channel facility. The flexor blades possess a low-damping and the flexor blades base an the air bearing base are free to oscillate only in the cross-flow direction. The Reynolds number of the experiments ranges from 2000 to 10000, and reduced velocities, based on natural frequency in still water, vary up to 13. The drag coefficient is increased by 20% for the h = 0.1D cylinder, and 60% for the h = 0.2D cylinder, comparing both with the plain cylinder. The smaller height strokes (h = 0.1D) do not prevent vortex formation in the region very close to the body, resulting in a decrease of about 50% of the amplitude response compared with the plain cylinder. Lowest amplitude response was found to the p = 10D and h = 0.2D case. The analysis of the vorticity contours shows that the shear layer does not roll close to the body (same result for the other cases with h = 0.2D).
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ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering
June 10–15, 2007
San Diego, California, USA
Conference Sponsors:
- Ocean, Offshore and Arctic Engineering Division
ISBN:
0-7918-4269-X
PROCEEDINGS PAPER
An Experimental Investigation of the Flow Around Straked Cylinders Available to Purchase
Ivan Korkischko,
Ivan Korkischko
University of Sa˜o Paulo, Sa˜o Paulo, SP, Brazil
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Julio R. Meneghini,
Julio R. Meneghini
University of Sa˜o Paulo, Sa˜o Paulo, SP, Brazil
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Rafael S. Gioria,
Rafael S. Gioria
University of Sa˜o Paulo, Sa˜o Paulo, SP, Brazil
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Paulo J. Jabardo,
Paulo J. Jabardo
University of Sa˜o Paulo, Sa˜o Paulo, SP, Brazil
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Enrique Casaprima,
Enrique Casaprima
Petrobras E&P, Rio de Janeiro, RJ, Brazil
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Ricardo Franciss
Ricardo Franciss
Petrobras CENPES, Rio de Janeiro, RJ, Brazil
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Ivan Korkischko
University of Sa˜o Paulo, Sa˜o Paulo, SP, Brazil
Julio R. Meneghini
University of Sa˜o Paulo, Sa˜o Paulo, SP, Brazil
Rafael S. Gioria
University of Sa˜o Paulo, Sa˜o Paulo, SP, Brazil
Paulo J. Jabardo
University of Sa˜o Paulo, Sa˜o Paulo, SP, Brazil
Enrique Casaprima
Petrobras E&P, Rio de Janeiro, RJ, Brazil
Ricardo Franciss
Petrobras CENPES, Rio de Janeiro, RJ, Brazil
Paper No:
OMAE2007-29057, pp. 641-647; 7 pages
Published Online:
May 20, 2009
Citation
Korkischko, I, Meneghini, JR, Gioria, RS, Jabardo, PJ, Casaprima, E, & Franciss, R. "An Experimental Investigation of the Flow Around Straked Cylinders." Proceedings of the ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. Volume 3: Pipeline and Riser Technology; CFD and VIV. San Diego, California, USA. June 10–15, 2007. pp. 641-647. ASME. https://doi.org/10.1115/OMAE2007-29057
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