Experimental investigation of cross flow - inline coupled Vortex-Induced Vibration on riser with finite length buoyancy module

2016 ◽  
Author(s):  
Jorlyn Le Garrec ◽  
Dixia Fan ◽  
Baiheng Wu ◽  
Michael S. Triantafyllou
Keyword(s):  
Experimental Investigation ◽  
Finite Length ◽  
Cross Flow ◽  
Vortex Induced Vibration

Experimental Investigation of the Effects of the In-Line Top-Motion on the Vortex-Induced Vibration Response of a Flexible Riser

2020 ◽  
Author(s):  
Wei Yang ◽  
Chuanzhen Ma ◽  
Zhuang Kang ◽  
Cheng Zhang ◽  
Shaojie Li
Keyword(s):  
Experimental Investigation ◽  
Vibration Frequency ◽  
Flow Direction ◽  
Excitation Frequency ◽  
Cross Flow ◽  
Excitation Amplitude ◽  
Flexible Cylinder ◽  
Amplitude Analysis ◽  
Vortex Induced Vibration ◽  
Flexible Risers

Abstract In order to understand the relation between top-motion and VIV of flexible risers, this paper presents an experimental investigation on concomitant vortex-induced vibration and top-motion excitation with flexible risers. The riser can was mounted vertically, with the diameter of 2 cm and the length of 5 m. The responses of amplitude, frequency and other parameters were analyzed in detail under conditions of different excitation amplitude and frequency in uniform flow. It was found that the concomitant VIV and top-motion excitation significantly affects the flexible cylinder response when compared to the pure VIV tests. The amplitude analysis results show that when the reduced velocity is small (less than about 15), the top-motion excitation has an important influence on amplitude of in-line directions. However, the excitation amplitude and frequency of in-line direction have a little influence on amplitude of cross flow direction. The frequency analysis results show that when the reduced velocity is small (less than about 5), the riser motion amplitude is small and irregular in different excitation and when the reduced velocity is large (5 < Ur < 55), the in-line vibration frequency is two times the cross-flow vibration frequency. A strong connection between the top-motion excitation frequency and the vibration frequency was also found. Overall, some phenomena and characteristics observed in the VIV considering top-motion excitation are different from those in classic VIV, which may provide basic reference for the VIV investigation involving the effect of floating bodies.

Experimental Investigation on the Vortex-Induced Vibration of the Cylinders with Helical Strakes

2011 ◽  
Vol 117-119 ◽  
pp. 747-750
Author(s):  
Yang Zhou ◽  
Wei Ping Huang
Keyword(s):  
Experimental Investigation ◽  
Optimal Design ◽  
Cross Flow ◽  
Comprehensive Analysis ◽  
Design Parameters ◽  
Vortex Induced Vibration ◽  
Flow Response ◽  
Helical Strakes ◽  
Uniform Current ◽  
Made In

The tests on the vortex-induced vibration (VIV) of the cylinders with different helical strakes were carried out in a uniform current. Both in-line and cross-flow responses were measured and a comprehensive analysis was made in order to understand the phenomenon of VIV mitigation by helical strake and find optimal design parameters, which are more effective for VIV mitigation, of helical strakes. The results show that the cross flow response of the cylinders with helical strakes could be reduced significantly and its in-line response may be enhanced severely. Therefore, much attention should be paid to the design of helical strake.

scholarly journals Experimental Investigation of the Vortex-Induced Vibration of a Curved Cylinder

2012 ◽  
Author(s):  
Gustavo R. S. Assi ◽  
Narakorn Srinil ◽  
Cesar M. Freire ◽  
Ivan Korkischko
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Circular Cylinder ◽  
Water Channel ◽  
Vortex Formation ◽  
Cross Flow ◽  
Streamwise Direction ◽  
Number Range ◽  
Vortex Induced Vibration ◽  
Horizontal Part

Experiments have been conducted in a water channel in order to investigate the vortex-induced vibration (VIV) response of a rigid section of a curved circular cylinder. Two curved configurations were tested regarding the direction of the approaching flow, a concave or a convex cylinder, in addition to a straight cylinder that served as reference. Amplitude and frequency response are presented versus reduced velocity for a wide Reynolds number range between 750 and 15,000. Trajectories in the cross-flow and streamwise direction are presented as well for several reduced velocities. Results show a distinct behaviour from the typical VIV of a straight cylinder highlighting the effect of curvature on vortex formation and excitation. The concave configuration presents relatively high amplitudes of vibration that are sustained beyond the typical synchronisation region. The mechanism behind the response is not yet clear, although authors suggest it might be related to some kind of buffeting excitation due to the disturbed flow from the upstream horizontal part.

An Experimental Investigation of the Dynamics of a Loosely Supported Tube Array

2017 ◽  
Author(s):  
Amro Elhelaly ◽  
Marwan Hassan ◽  
Atef Mohany ◽  
Soha Moussa
Keyword(s):  
Experimental Investigation ◽  
Impact Force ◽  
Cross Flow ◽  
Open Loop ◽  
Diameter Ratio ◽  
Force Level ◽  
Steam Generators ◽  
Flow Induced Vibration ◽  
System Integrity ◽  
Tube Bundles

The integrity of tube bundles is very important especially when dealing with high-risk applications such as nuclear steam generators. A major issue to system integrity is the flow-induced vibration (FIV). FIV is manifested through several mechanisms including the most severe mechanism; fluidelastic instability (FEI). Tube vibration can be constrained by using tube supports. However, clearances between the tube and their support are required to allow for thermal expansion and for other manufacturing considerations. The clearance between tubes may allow frequent impact and friction between tube and support. This in turn may cause fatigue and wear at support and potential for catastrophic tube failure. This study aims to investigate the dynamics of loosely supported tube array subjected to cross-flow. The work is performed experimentally in an open-loop wind tunnel to address this issue. A loosely-supported single flexible tube in both triangle and square arrays subjected to cross-flow with a pitch-to-diameter ratio of 1.5 and 1.733, respectively were considered. The effect of the flow approach angle, as well as the support clearance on the tube response, are investigated. In addition, the parameters that affect tube wear such as impact force level are presented.

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