Model Testing on Cross-Flow Vortex-Induced Vibration in Combined In-Line Current and Oscillatory Flows

2010 ◽  
Author(s):  
Franc¸ois Moreau ◽  
Shan Huang
Keyword(s):  
Reynolds Number ◽  
Current Flow ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Test Results ◽  
Oscillatory Flows ◽  
Vortex Induced Vibration ◽  
Towing Tank ◽  
Towing Speed ◽  
Flow Vortex

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.

Study on the Test Results of Cross-Flow Vortex-Induced Vibration of a Towed Circular Cylinder

2014 ◽  
Author(s):  
Wei-Wu Wu ◽  
Quan-Ming Miao ◽  
Yan-Xia Wang
Keyword(s):  
Circular Cylinder ◽  
Natural Frequency ◽  
Cross Flow ◽  
Test Cases ◽  
Test Results ◽  
Vortex Induced Vibration ◽  
Low Mass ◽  
Low Mass Ratio ◽  
Flow Vortex ◽  
Lock In

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.

scholarly journals An Experimental Evaluation of Vortex-Induced Vibration of a Riser Bundle With Gaps

2009 ◽  
Author(s):  
J. Kim Vandiver ◽  
Yongming Cheng ◽  
Vivek Jaiswal ◽  
Aditi Sheshadri ◽  
Alan Yu
Keyword(s):  
Free Vibration ◽  
Model Test ◽  
Flow Direction ◽  
Angle Of Attack ◽  
Cross Flow ◽  
Test Results ◽  
Vortex Induced Vibration ◽  
Towing Tank ◽  
Helical Strakes ◽  
Rigid Model

VIV model test results are presented for a bundle of three parallel pipes all lying in the same plane, similar to a riser with large kill and choke lines. The rigid model was attached to a spring-mounted frame in the MIT towing tank. The horizontal model was towed in the tank and allowed to respond in free vibration to vortex-induced vibration in the cross-flow direction. The angle of attack of the model was varied from 0 to 90 degrees. The model was tested with and without helical strakes. Without strakes the model exhibited significant vibration at 0 and 90 degrees angle of attack. Strakes suppressed VIV at all angles of attack.

Turbulent Wake of a Stack and the Influence of Velocity Ratio

2006 ◽  
Author(s):  
M. S. Adaramola ◽  
D. Sumner ◽  
D. J. Bergstrom
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Reynolds Shear Stress ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Turbulent Wake ◽  
Mean Velocity ◽  
Distinct Structure ◽  
Flow Reynolds Number ◽  
Cross Flow Velocity

The effect of the jet-to-cross-flow velocity ratio, R, on the turbulent wake of a cylindrical stack of AR = 9 was investigated with two-component thermal anemometry. The cross-flow Reynolds number was ReD = 2.3×104, the jet Reynolds number ranged from Red = 7×103 to 4.6×104, and R was varied from 0 to 3. The stack was partially immersed in a flat-plate turbulent boundary layer, with a boundary layer thickness-to-height ratio of δ/H = 0.5 at the location of the stack. The flow around the stack was broadly classified into three flow regimes depending on the value of R, which were the downwash (R < 0.5), cross-wind dominated (0.5 < R < 1.5), and jet-dominated (R > 1.5) regimes. Each flow regime had a distinct structure to the mean velocity (streamwise and wall-normal directions), turbulence intensity (streamwise and wall-normal directions), and Reynolds shear stress fields.

On Vortex Induced Vibration in Two-Degree-of-Freedoms of Flexible Cylinders

2011 ◽  
Author(s):  
Weiping Huang ◽  
Weihong Yu
Keyword(s):  
Natural Frequency ◽  
Current Velocity ◽  
Coupling Effect ◽  
Great Influence ◽  
Cross Flow ◽  
Flexible Cylinder ◽  
Fluid Structure ◽  
Vortex Induced Vibration ◽  
Flow Vortex ◽  
Lock In

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.

scholarly journals Effect of Jet Inclination Angle and Hole Exit Shape on Vortical Flow Structures in Low-Reynolds Number Jet in Cross-Flow

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
Yufeng Yao ◽  
Mohamad Maidi ◽  
Jun Yao
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Inclination Angle ◽  
Qualitative Agreement ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Vortical Flow ◽  
Flow Structures ◽  
Good Qualitative Agreement ◽  
The Cross

Numerical studies have been performed to visualize vortical flow structures emerged from jet cross-flow interactions. A single square jet issuing perpendicularly into a cross-flow was simulated first, followed by two additional scenarios, that is, inclined square jet at angles of 30° and 60° and round and elliptic jets at an angle of 90°, respectively. The simulation considers a jet to cross-flow velocity ratio of 2.5 and a Reynolds number of 225, based on the free-stream flow quantities and the jet exit width in case of square jet or minor axis length in case of elliptic jet. For the single square jet, the vortical flow structures simulated are in good qualitative agreement with the findings by other researchers. Further analysis reveals that the jet penetrates deeper into the cross-flow field for the normal jet, and the decrease of the jet inclination angle weakens the cross-flow entrainment in the near-wake region. For both noncircular and circular jet hole shapes, the flow field in the vicinity of the jet exit has been dominated by large-scale dynamic flow structures and it was found that the elliptic jet hole geometry has maximum “lifted-off” effect among three hole configurations studied. This finding is also in good qualitative agreement with existing experimental observations.

Experimental Evaluation of Pure In-Line Vortex Induced Vibration (VIVx) of Low Mass-Damping Ratio Cylinder

2016 ◽  
Author(s):  
Mohammad Mobasher Amini ◽  
Antonio Carlos Fernandes
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Damping Ratio ◽  
Cross Flow ◽  
Current Channel ◽  
Number Range ◽  
Vortex Induced Vibration ◽  
Numerical Studies ◽  
Lower Amplitude ◽  
Low Mass

Numerous experimental and numerical studies have been carried out to better understand and to improve prediction of cylinder VIV (vortex Induced Vibration) phenomenon. The behavior of cylinder due to in-line vibration (VIVx) has been neglected in the earlier studies because of its lower amplitude in comparison with cross flow vibration (VIVy). However, some researchers have studied VIVx in 2DOF along with VIVy. Recent investigations show that response amplitude of structure caused by VIVx is large enough to bring it to consideration. This study focuses on understanding the origin and prediction of VIVx amplitude exclusively in 1DOF and subcritical flow regime. The experiments were performed in current channel on bare circular cylinder with low mass-damping ratio in Reynolds number range Re = 10000 ∼ 45000.

Investigating cross-flow vortex-induced vibration of top tension risers with different aspect ratios

2021 ◽  
Vol 221 ◽  
pp. 108497
Author(s):  
Guijie Liu ◽  
Haiyang Li ◽  
Yingchun Xie ◽  
Atilla Incecik ◽  
Zhixiong Li
Keyword(s):  
Cross Flow ◽  
Vortex Induced Vibration ◽  
Aspect Ratios ◽  
Flow Vortex

scholarly journals Trajectory of a synthetic jet issuing into high-Reynolds-number turbulent boundary layers

2018 ◽  
Vol 856 ◽  
pp. 531-551 ◽  
Author(s):  
Tim Berk ◽  
Nicholas Hutchins ◽  
Ivan Marusic ◽  
Bharathram Ganapathisubramani
Keyword(s):  
Reynolds Number ◽  
Boundary Layers ◽  
High Reynolds Number ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Turbulent Boundary Layers ◽  
Synthetic Jet ◽  
Actuation Frequency ◽  
The Cross ◽  
High Reynolds

Synthetic jets are zero-net-mass-flux actuators that can be used in a range of flow control applications. For some applications, the scaling of the trajectory of the jet with actuation and cross-flow parameters is important. This scaling is investigated for changes in the friction Reynolds number, changes in the velocity ratio (defined as the ratio between the mean jet blowing velocity and the free-stream velocity) and changes in the actuation frequency of the jet. A distinctive aspect of this study is the high-Reynolds-number turbulent boundary layers (up to $Re_{\unicode[STIX]{x1D70F}}=12\,800$) of the cross-flow. To our knowledge, this is the first study to investigate the effect of the friction Reynolds number of the cross-flow on the trajectory of an (unsteady) jet, as well as the first study to systematically investigate the scaling of the trajectory with actuation frequency. A broad range of parameters is varied (rather than an in-depth investigation of a single parameter) and the results of this study are meant to indicate the relative importance of each parameter rather than the exact influence on the trajectory. Within the range of parameters explored, the critical ones are found to be the velocity ratio as well as a non-dimensional frequency based on the jet actuation frequency, the cross-flow velocity and the jet dimensions. The Reynolds number of the boundary layer is shown to have only a small effect on the trajectory. An expression for the trajectory of the jet is derived from the data, which (in the limit) is consistent with known expressions for the trajectory of a steady jet in a cross-flow.

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