One and two degrees-of-freedom Vortex-Induced Vibration experiments with yawed cylinders

Autor(es)

Franzini, G. ^[1] ; Goncalves, R. T. ^[2] ; Meneghini, J. R. ^[1] ; Fujarra, A. L. C. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, POLI, NDF Fluids & Dynam Res Grp, BR-05508 Sao Paulo - Brazil

^[2] Univ Sao Paulo, POLI, TPN Numer Offshore Tank, BR-05508 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF FLUIDS AND STRUCTURES; v. 42, p. 401-420, OCT 2013.
• Citações Web of Science: 32

Resumo

Vortex-Induced Vibration (VIV) experiments were carried out with yawed cylinders. The purpose was to investigate the validity of the Independence Principle (IP) for properly describing the flow characteristics and the dynamics of structures subjected to oblique flow. Five yaw angles in relation to the direction perpendicular to the free stream velocity were tested, namely theta = 0 degrees, 10 degrees, 20 degrees, 30 degrees and 45 degrees. Both the upstream and downstream orientations were tested. The models were mounted on a leaf spring apparatus that allows experiments with one or two degrees of freedom. The Reynolds numbers based on the component normal to the cylinder axis fell in the interval 3 x 10(3) < Re-n < 1.5 x 10(4). The mass ratio parameter was m{*} = 2.6 and the cylinder aspect ratio was L/D approximate to 13 for all the experiments. Time histories of displacement and hydrodynamic forces were acquired. Considering only the component of the free stream which is normal to the cylinder axis, the results of amplitude and force coefficients agreed reasonably well with the non-yawed ones for yaw angles up to 20 degrees for both one and two degrees-of-freedom experiments. This indicates the validity of the IP for this yaw angle range. For yaw angles larger than 20 degrees, a decrease in the maximum amplitude was observed. The decrease in the oscillation amplitudes was related to a larger modulation in the phase shift between force and displacement. Differences in the results for upstream and downstream were observed and were more evident for the larger yaw angle. These differences can be associated to the asymmetric cylinder end conditions. (C) 2013 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 08/00688-4 - Investigação do fenômeno de VIV Vibração Induzida por Vórtices: em cilindros flexíveis
• Beneficiário: Guilherme Rosa Franzini
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto