Cross-flow vortex-induced vibration of a flexible riser transporting an internal flow from subcritical to supercritical

2017 ◽  
Vol 139 ◽  
pp. 74-84 ◽  
Author(s):  
Shuai Meng ◽  
Xiaoqing Zhang ◽  
Chidong Che ◽  
Weijing Zhang
Author(s):  
Weiping Huang ◽  
Weihong Yu

In this paper, an experimental study on the in-line and cross-flow vortex-induced vibration (VIV) of flexible cylinders is conducted. The relationship of two-degree-of-freedoms of vortex-induced vibration of flexible cylinders is also investigated. The influence of natural frequency of flexible cylinders on vortex shedding and VIV are studied through the experiment in this paper. Finally, A nonlinear model, with fluid-structure interaction, of two-degree-of-freedom VIV of flexible cylinders is proposed. It is shown that the ratio of the frequencies and amplitudes of in-line and cross flow VIV of the flexible cylinders changes with current velocity and Reynolds number. The natural frequency of flexible cylinder has great influence on the vortex-induced virbation due to the strong fluid-structure coupling effect. Under given current velocity, the natural frequency of flexible cylinder determines its forms of vibration (in circular or ‘8’ form). The ratio of the VIV frequencies is 1.0 beyond the lock in district and 2.0 within the lock in district respectively. And the ratio of the VIV amplitudes is 1.0 beyond the lock in district and 1/3 to 2/3 within the lock in district. The results from this paper indicates that in-line vibration should be considerated when calculating the vibration response and fatigue damage.


Author(s):  
Franc¸ois Moreau ◽  
Shan Huang

The cross-flow vibration of a cylinder in co-linear steady and oscillatory flows is investigated in towing tank for the inline Keulegan Carpenter number varying from 5 to 27 and for the reduced velocity varying from 3 to 19. The reduced velocity is defined by adding together the towing speed and the maximum in-line oscillating velocity. The ratio between the maximum in-line oscillating velocity and the total in-line velocity, i.e. including the towing speed, varies from 0.1 to 0.8. The Reynolds number is in the sub-critical regime. The model test results show that cross-flow vortex-induced vibration (VIV) in combined wave and current flow is significantly different from that in current or wave alone. The response is very much dependent upon the velocity ratio between the current and wave particle velocity.


2021 ◽  
Vol 221 ◽  
pp. 108497
Author(s):  
Guijie Liu ◽  
Haiyang Li ◽  
Yingchun Xie ◽  
Atilla Incecik ◽  
Zhixiong Li

2021 ◽  
pp. 2150248
Author(s):  
Jin-Long Duan ◽  
Xu Wang ◽  
Ke Chen

The dynamics of a full-scale pipe conveying fluid inside is investigated based on the finite element method (FEM). During the numerical simulation, the Euler–Bernoulli beam equations are used to model the motion of the full-scale pipe while the effect of internal flow is considered. And the semi-empirical time-domain model is applied to simulate the external hydrodynamic forces exerted on the pipe. Then the typical vortex-induced vibration (VIV) characteristics of the full-scale pipe considering both internal and external flows are analyzed. The results show that with the increase of the internal flow velocity, the natural frequencies of the full-scale pipe decrease and the in-line (IL) and cross-flow (CF) dominating modes are increased. Furthermore, the dominating frequencies in both IL and CF directions are not notably changed. And the IL and CF root-mean-square (RMS) values of amplitudes fluctuate at around the stable values due to the stable external hydrodynamic forces. It should be noticed that the IL and CF RMS strain values of the full-scale pipe are increased, especially for high external and internal flow velocities. The maximal RMS strain values in both IL and CF directions appear next to the pipe top, which could have an influence on the motion of the ship on the sea surface.


2014 ◽  
Author(s):  
Wei-Wu Wu ◽  
Quan-Ming Miao ◽  
Yan-Xia Wang

This paper gives a review on VIV experimental research. A detailed introduction of the experimental study on the cross-flow vortex-induced vibration of a towed circular cylinder in CSSRC’s towing tank is presented and classical VIV phenomena are explained and analyzed in this study. However, some results which are much different from those in the classical literatures in the past few decades are observed at the same time. For example, instead of reduced velocity Ur from 5 to 8, the “lock-in” region happened in the reduced velocity ranged from 10 to 14 in our tests, where the reduced velocity is calculated by the natural frequency. The non-dimensional frequency (oscillation frequency over natural frequency) of about 1.8 in the “lock-in” region is also different from that of 1.0 in the classical literatures. Interestingly, the author found that some of the results given by Moe and Wu (1990), Sarpkaya (1995), Govardhan and Williamson (2000), Pan zhiyuan (2005) and so on, reported the similar phenomenon. Since above listed papers have the same points of view, whether can we say that the results in this paper are possible for the case of low mass ratio. To conclude that, however, many questions need to be answered. In an effort to gain a better understanding of VIV phenomenon, this paper presents results of further analysis on the test cases and parameters.


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