Vortex-induced Vibration Suppression Research Articles

Experiment study on vortex-induced vibration of a twin-box girder with large cantilever plates

Due to their good aerodynamic stability performance, twin-box girders are frequently adopted in long-span cable-supported bridges. However, they are also susceptible to vortex-induced vibration (VIV) since the central slot changes the flow patterns around a bridge girder. In this paper, the VIV performance of a twin-box girder with large cantilever plates was investigated through wind tunnel tests of sectional models with 1:75 and 1:30 scale ratios. Furthermore, the effects of increasing the damping ratio and installing various conventional aerodynamic countermeasures such as guide vanes, grid plates, and central stabilizers on VIV suppression of the twin-box girder were investigated. A new type of aerodynamic countermeasure named the L-shaped windshield was proposed to suppress the VIV response of the twin-box girder to an acceptable level. The results indicated that significant vertical VIV occurred for the twin-box girder, and increasing the damping ratio and installing conventional aerodynamic countermeasures could not suppress the VIV response of the twin-box girder effectively. The attachments obviously worsened the vertical VIV performance of the twin-box girder, and the attachments on the upper surface showed a more significant effect. It was further demonstrated that the L-shaped windshield is an effective countermeasure that can completely suppress the vertical VIV of the twin-box girder by greatly reducing the motion-induced vortexes in the central slot with the help of low turbulence in the turbulent flow field.

Vortex shedding characteristics and hydrodynamic forces of stationary and elastically mounted side-by-side cylinders fitted with small diameter control rods

Vortex shedding behind bluff bodies can induce noise and vibration problems when it engages in a feedback cycle of oscillations with an acoustic or structural mode. Therefore, several passive and active flow control techniques have been developed to suppress vortex shedding behind a single bluff body. However, less attention was given to the case of multiple bluff bodies in cross-flow. Therefore, in this paper, a numerical investigation is performed to study the effect of adding small diameter control rods in the vicinity of two side-by-side cylinders on the vortex shedding characteristics, the hydrodynamic fluid forces, as well as the suppression of vortex-induced vibration. The simulations are conducted at a Reynolds number of Re = 200 and the side-by-side cylinders have a spacing ratio of T∗=2.5. The number of control rods and their angular positions around the main cylinders are varied. Fitting the side-by-side cylinders with control rods has resulted in three different flow regimes compared to the base case with no control rods. These flow regimes depend on the angular positions of the control rods and they are classified as; bistable flow, stable biased flow, and merged wake flow regimes. The stable biased flow regime has resulted in the maximum reduction of the fluctuating lift coefficient of the side-by-side cylinders, especially when the control rods are placed at θ=135° from the flow stagnation point. Increasing the number of control rods around the cylinders has further reduced the fluctuating lift coefficient and produced a more symmetric wake at the rod angles which produce the stable biased flow, and the merged wake flow regimes. The vortex-induced vibration of the side-by-side cylinders is investigated when the control rods are placed at the angular position that results in a stable biased flow regime. It is revealed that fitting the cylinders with control rods at an angular position of θ=135° has resulted in reducing the vibration amplitude over the whole range of the simulated reduced flow velocities, which makes this technique a viable one to control the vortex shedding and the vortex-induced vibration of side-by-side cylinders.

Vortex induced coupled vibration of an elastically mounted square cylinder with a detached solid and flexible plate

The vortex induced coupled vibration of an elastically mounted square cylinder with a detached solid/flexible plate at Re=150 is numerically investigated in the present work. Influences of non-dimensional plate length L*, gap distance G* and plate flexibility ω* on vibration responses, flow physics and filament motion are analyzed. For a square cylinder-detached solid plate system, a short plate (L*= 0.25, 0.5) can suppress vortex induced vibration (VIV) in a wide range of G*(0≤G*≤2). In the optimal situation, the vibration can be suppressed almost completely (98% reduction in Ay*). A long solid plate suppresses VIV at a small G*. Nonetheless, it enhances vibration at a large G*. The effective range of G* (range of G* enables VIV suppression) shrinks fast with an increasing plate length. Two mechanisms for an effective VIV suppression are summarized by examining the transient flow fields. On the other hand, a square cylinder-detached flexible plate system maintains a more stable VIV suppression performance within a wide range of G* (0.5≤G*≤2.0) and ω* (0.5≤ω*≤3.0). A more compelling advantage is that, flexibility turns VIV enhancing to VIV suppression at large gap distance (G*=2.0). Although varying flexibility in a wide range gives marginal effect on response statistics, the filament motion undergoes drastic changes. Three types of flapping motion are observed. They are symmetric flapping, asymmetric flapping, and a most interesting one, flow induced reversed flapping (FIRF), which occurs at large gap distance and high flexibility (G*=2.0 and ω*=3.0). The necessary conditions and the onset of reversed flapping are also analyzed. FIRF can be viewed as an automatic gap distance adjusting mechanism. Through it, a shortened gap distance prevents strong and immediate vortex shedding behind the square cylinder, and a good VIV suppression performance can be obtained. This work can help in improving understanding of complex multi-physics coupling FSI problems. Moreover, analyses on VIV responses of a square cylinder-detached plate system can also provide guidance in passive flow control of VIV of a square cylinder.

Investigation of Vortex-Induced Vibration of Double-Deck Truss Girder with Aerodynamic Mitigation Measures

The long-span double-deck truss girder bridge has become a recommend structural form because of its good performance on traffic capacity. However, the vortex-induced vibration (VIV) characteristics for double-deck truss girders are more complicated and there is a lack of related research. In this research, wind tunnel tests were utilized to investigate the VIV characteristics of a large-span double-deck truss girder bridge. Meanwhile, the VIV suppression effect of the aerodynamic mitigation measures was measured. Furthermore, the VIV suppression mechanism was studied from the perspective of vortex shedding characteristics. The results indicated that the double-deck truss girder had a significant VIV when the wind attack angles were +3° and +5°. The aerodynamic mitigation measures had an influence on the VIV response of the double-deck truss girder. The upper chord fairing and lower chord inverted L-shaped deflector plate played a crucial role in suppressing VIV. Numerical analysis indicated that vortex shedding above the upper deck or in the wake region may dominate vertical VIV, while vortex shedding in the wake region of the lower deck may dominate torsional VIV. The upper chord fairing and lower chord inverted L-shaped deflector plate disrupted the original vortex shedding pattern in both regions, thereby suppressing VIV. This research can provide a foundation for bridge design and vibration suppression measures for large-span double-deck truss girder bridges.

Dynamic Response of Two-Degree-of-Freedom Riserless Drill String for Vortex-Induced Vibration Suppression and Enhancement

Dynamic Response of Two-Degree-of-Freedom Riserless Drill String for Vortex-Induced Vibration Suppression and Enhancement

Vortex-Induced vibration suppression for a cylinder with random grooves inspired by rough tree bark

The vortex-induced vibration (VIV) response of a 2-degree-of-freedom cylinder with random grooves is investigated numerically based on the Reynolds Average Navier–Stokes (RANS) method. The Newmark-β method is used to solve the equations of motion of the cylinder. The effects of the random groove on VIV suppression are discussed in detail. The coverage ratios (k) of the random groove include 0%, 25%, 50%, 75%, and 100%. The vibration suppression effect of k = 75% and k = 100% is not significant. However, the VIV amplitude of the cylinders with k = 25% is greatly suppressed. In particular, the cross-flow amplitude ratio is reduced from 1.50 (k = 0%, a smooth cylinder) to 0.65 (k = 25%). First, the boundary-layer separation point of the grooves is fixed, so the random grooves destroy the normal separation and development of the main vortices. Therefore, two rows of vortices with different sizes are generated on both sides of the cylinder, which may cause unstable vibration. Meanwhile, a series of small vortices are formed in the grooves. These small vortices cannot merge synchronously into the main vortices and further reduced the strength of the main vortices. Consequently, the driving force of the vibration, which is generated by the main vortices, is reduced. As a result, the VIV responses are suppressed.

Experimental investigation of vortex-induced vibrations of a flexibly mounted cylinder in a shear-thinning fluid

We show experimentally that shear thinning can cause suppression of vortex-induced vibration (VIV). Increasing shear thinning in a fluid flow causes a decrease in the critical Reynolds number at which VIV occurs. VIV occurs within a range of reduced velocity, called the lock-in range. The reduced velocity at which lock-in begins, the width of the lock-in range, and the oscillation amplitude decrease for a shear thinning fluid, and beyond a critical concentration, oscillations are completely suppressed.

Suppression of Vortex-induced vibration of a circular cylinder with a pair of curved plates

A pair of curved plates are installed behind the cylinder to suppress the VIV response of the cylinder. The effects of the distances (e = 1D, 2D, 3D and 6D) between the cylinders and the curved plates and plate lengths (L = 0.1D, 0.5D and 1D) on the VIV response are simulated by combining k-ω SST turbulence models and uRANS equations. The accuracy of the numerical simulation is verified by comparison with the experiment data. The results show that when e = 3D, the curved plate has the best vibration suppression effect on the VIV response. The maximum amplitude ratio is 0.56, which is 42% less than that of the bare cylinder (0.98). When e = 1D, the curved plates enhance the VIV response. Especially in the lower branch, the amplitude ratio reaches 0.93, which is far greater than that of the bare cylinder. In addition, when U*>10, the cylinder with a pair of curved plates exits the lock-in region. Besides, the vibration suppression effect of plate length on cylinder is further studied. When L = 1D, the curved plate has the best vibration suppression effect on the cylinder. The maximum amplitude ratio is 0.37, which is 62% less than that of the bare cylinder.

Flow control of an elastically mounted square cylinder by using an attached flexible plate

This work numerically investigates the flow control of an elastically mounted square cylinder by using an attached plate placing downstream. The flow control effect by using a long solid/flexible plate for a circular cylinder has been widely discussed. However, the effect of a short plate is not clear. In addition, few knowledge is known for VIV (vortex-induced vibration) suppression effect for a square cylinder by using a solid/flexible plate. The present work systematically studies the influence of plate length and flexibility on VIV suppression for an elastically mounted square cylinder at Reynolds number 150. First, the effect of a solid plate with non-dimensional length varying in a wide range 0.5≤L*≤3.0 is analyzed. Significant VIV suppression can be achieved by using an attached solid plate, even with a plate at a short length. The influence of flexibility is more complex. A short flexible plate is less effective than a solid plate with the same length. On the other hand, a long flexible plate with medium flexibility can further enhance VIV suppression. A maximum 96% reduction in the vibration amplitude can be achieved by using a long flexible plate with optimal flexibility. Additionally, two VIV suppression mechanisms for an elastically mounted square cylinder with an attached plate are concluded, and the influence of flexibility for both short and long plates is also analyzed.

Role of moveable guide vane with various configurations in controlling the vortex-induced vibration of twin-box girder suspension bridges: An experimental investigation

The purpose of this paper is to investigate the effects of a moveable guide vane with various configurations (i.e., horizonal length and stiffness) in controlling the vortex-induced vibration (VIV) of a long-span suspension bridge with twin-box girder. First, a series of VIV tests of the 1:50 scaled ratio of sectional model with various guide vane configurations were performed. The vertical and torsional displacements of the twin-box girder as well as the vertical response of the windward and leeward guide vane measured to analyze the movement characteristics of the main girder and guide vanes, respectively. The test results show that, the moveable guide vane could significantly reduce the maximum vertical and torsional displacement responses of the main girder with an immovable guide vane or without a guide vane, especial under the most unfavorable wind attack angle of +3°. In addition, a moveable guide vane with relatively low stiffness could produce a better outcome of VIV control. Furthermore, the increase of the horizontal length of the guide vane could have a negative impact on the VIV control of the bridge. Importantly, the maximum vertical amplitude of the moveable guide vane is generally larger than that of the main girder, indicates that the leeward guide vane could play an important role in the VIV suppression when the stiffness of the guide vane is over certain threshold (e.g., 19 g/mm).

Numerical investigation of vortex-induced vibrational responses to a flexible tensioned riser with symmetric grooves in uniform currents

The vortex-induced vibration (VIV) responses to a flexible tensioned cylindrical riser, which the cross section is fixed with two symmetric grooves, is numerically researched by the inhouse viv3D-FOAM-SJTU solver developed based on the OpenFOAM and thick strip model. The Reynolds-averaged Navier-Stokes (RANS) method and Euler-Bernoulli bending beam model are coupled to obtain the hydrodynamics forces and displacements in the vibration process of riser exposed to uniform current. The configurations of riser are designed to spanwise grooves with three different angles (45°,90°, 135°) to the incoming flow, and the three different groove depths and four flow velocities are selected for further investigation. Results show that the flow is broken in the groove, forming the internal small vortices, when the groove degree is 45°, the complex VIV responses are generated due to the change of flow separation point and the interference of internal small vortices on the development of large-scale vortices on the surface of the riser. As the groove degree reaches to 90°, the interference of internal small vortices leads to VIV suppression, and the internal small vortices is released directly into the wake field to enhance VIV with the groove degree = 135°. As the depth of the groove increases, the effect on the flow field is also enhanced, and the vortex structure along the span of the flow field is affected by the position and depth of the groove. Therefore, the geometries of the groove degree = 90° and depths = 0.12D, 0.16D (D is the riser diameter) present the best VIV suppression effect, and the configurations of two other groove degrees are failed to suppress the VIV well.

An experimental study on vortex-induced vibration suppression for submarine multispan pipelines

To ensure structural safety, it is necessary to reduce the vortex-induced vibration (VIV) of free-span pipelines in offshore engineering applications. In this study, an experimental investigation on VIV suppression for submarine multispan pipelines was conducted. The VIV response was suppressed by attaching helical strakes to the pipeline. By comparing the vibration response of a smooth multispan pipeline with that of a pipeline with an installed suppression device, the suppression effect of the helical strakes was explored. The coverage of the helical strakes was changed, and differences in the VIV suppression effects were observed in the experiment. The helical strakes effectively suppressed VIV of the multispan pipeline, and the maximum suppression efficiency exceeded 90%. The inhibition effect increased with increasing strake coverage. Furthermore, the burial depth of the pipeline was found to influence the VIV suppression effect.

Study on the parameters of detached splitter plate for VIV suppression

Cylindrical structures such as offshore risers and offshore platform legs will suffer fatigue damage due to Vortex-induced Vibration (VIV). It is necessary to study the suppression scheme of cylindrical VIV. The rigid splitter plate has the characteristics of simple structure, low maintenance cost, and no external energy. Therefore, it becomes one of the suitable VIV suppression schemes. Based on numerical simulations, the design of a downstream detached splitter plate is investigated at a fixed flow rate. The suppression effects of 3 main parameters, distribution gap, splitter plate width and splitter plate length, are analysed. The study found that there is an obvious effective action interval for the distribution gap. The splitter plate provides better suppression when the gap is within this interval. In addition, the length of the splitter plate is the most significant parameter for the suppression effect. When the length is too small, the vibration response of the cylinder will be further aggravated. As the length continues to increase, so does the overall suppression effect of the splitter plate. Therefore, when the 3 parameters are properly combined and the length is as long as possible within the feasible range, the splitter plate can achieve a significant suppression effect.

On the study of vortex-induced vibration of a straked pipe in bidirectionally sheared flow

Helical strakes are widely used to suppress vortex-induced vibration (VIV) in ocean engineering. However, the VIV response and suppression efficiency of the straked pipe are unclear under the recently discovered bidirectionally sheared flow field. Experiments on vortex-induced vibration for a flexible pipe with three kinds of helical strakes were carried out in an ocean basin. The bare pipe model was 28.41mm in diameter and 7.64m in length. Three kinds of helical strakes with different pitch/height (17.5D/0.15D, 17.5D/0.25D,and 17.5D/0.35D) were applied. The test was performed on a rotating test rig to simulate bidirectionally sheared flow conditions. Fiber Bragg Grating (FBG) strain sensors were arranged along the test pipe to measure bending strains, and the modal analysis approach was used to determine the VIV response. The reduced velocities based on the tested first natural frequency of the bare pipe in water reached 30.79. The cross-flow and in-line VIV amplitudes, VIV suppression efficiency, and fatigue damage are presented in this article. The results showed that the helical strakes can suppress bidirectionally sheared flow-induced VIV significantly at a high reduced velocity regime with fatigue damage suppression efficiency over 99% in the CF and IL directions, but cannot suppress the in-line initial displacement, which was also found in previous studies as a drawback of helical strakes.

Experimental exploration of unpowered propellers for vortex-induced vibration suppression of flexible riser

Passive control of the vortex-induced vibrations (VIVs) of flexible risers has been typically studied to alleviate their VIV responses by means of breaking the spanwise correlation, modifying the structural characteristic, or disturbing the flow field. However, this paper proposed using innovative suppression devices—unpowered propellers—to mitigate VIVs and output energy through passive rotation under flowing fluids. The effectiveness of three-, four-, and six-blade propellers for VIV suppression was experimentally examined in the Reynolds number range of 2600–10,400. Seven identical propellers were installed uniformly along a riser facing the incoming flow for VIV suppression. The response parameters of the riser models, including the displacement, frequency, trajectory, and fatigue damage, were investigated. Moreover, a comprehensive evaluation of the unpowered propellers, determined by the suppression efficiency and the cost, was also conducted. The experimental results showed that all three types of propellers significantly decreased the VIV amplitudes and inhibited high-order frequency components. Increasing the number of blades effectively enhanced the amplitude suppression of the propellers, whereas it had almost no effect on the vibration frequencies of the controlled risers. It is worth noting that the three-blade propellers with the best comprehensive evaluation may not be a reasonable choice in high-velocity water.

Experimental investigation on the effectiveness of serrated helical strakes in suppressing vortex-induced vibrations for a flexible riser

The effectiveness of an unconventional configuration of serrated helical strakes (SSs) in alleviating the vortex-induced vibrations (VIVs) of flexible risers was evaluated experimentally in the Reynolds number range of 2600–10,400. Five SSs with varying serration densities and lengths were designed and compared with conventional strakes (CSs) to highlight the unparalleled features of this new geometry. The VIV parameters of the bare and straked risers, including the displacement, frequency, fatigue damage, and suppression efficiency, were systematically investigated. The comprehensive evaluation of the helical strakes was also made considering the factors of amplitude suppression, frequency inhibition, drag force, and cost control. The experimental results confirmed that all the helical strakes were capable of suppressing the VIV responses of flexible riser models. With identical strake areas, the SSs were more effective in inhibiting the VIV amplitude and fatigue damage than the CSs; whereas, the serrated geometry had few effects in improving the reduction of VIV frequency. Moreover, serration density is a critical factor in determining the suppression performance of SSs under the same strake heights and areas. An increase in the strake area enhanced VIV suppression performance; however, excess strakes deteriorated the comprehensive evaluation index due to the increased cost.

Comparative Study of the Flow-Induced Vibration of a Circular Cylinder Attached With Front and/or Rear Splitter Plates at a Low Reynolds Number of 120

Abstract This paper numerically investigates the flow-induced vibration of a circular cylinder attached with front and/or rear splitter plates at a low Reynolds number of Re = 120. The effects of plate length and plate location on the hydrodynamic coefficient, vibration response, and flow wake are examined and discussed in detail. The results reveal that the hydrodynamic coefficient of the cylinder with a single rear plate is significantly reduced at Ur ≤ 8 (Ur is the reduced velocity), resulting in the vortex-induced vibration (VIV) suppression. Nevertheless, the galloping is excited at Ur > 8 due to the hydrodynamic instability, accompanied by the jump of response amplitude and hydrodynamic force, as well as the abrupt drop of response frequency. The alternate reattachment of shear layers on the plate surface introduces an extra lift force that strengthens the vibration response. By introducing an individual front plate, significant VIV suppression is achieved. The vibration exhibits variable patterns when the cylinder is equipped with bilateral plates, including the typical VIV mode, weak VIV-galloping coupling mode, and IB-galloping-DB mode (IB and DB represent the initial branch and desynchronization branch of VIV, respectively). The galloping branch in IB-galloping-DB mode is observed with an abrupt drop in response frequency, as well as a tiny time lag between the displacement and lift force. The vibration response is significantly suppressed when the cylinder is simultaneously equipped with a 1D front plate and a 1–2D rear plate due to the streamlined profile.

Flow-induced vibration of flexible cylinders covered by fixed fairings with different chord-thickness ratios

Fairings are important vortex-induced vibration (VIV) suppression devices in the offshore and marine engineering applications. For circular cylinders in the marine structures, both their mean deflection in the in-line direction and the oscillation amplitude in the cross-flow direction can be effectively reduced when the fairings work properly. However, plenty recent investigations report that when the rotational elements of fairings fail to function, the VIV suppression functions may be deprived and severe galloping oscillations may occur. However, very few studies discussed the galloping oscillation mechanism for slender flexible cylinders. We perform a numerical study on the fluid–structure interaction of flexible cylinders covered by fixed fairings with different chord-thickness ratios (c/t) using a self-developed fluid–structure interaction simulation code. The Reynolds number is 1.68×104, which is based on the incoming velocity and the diameter of the cylinder. It is found that large amplitude, low frequency and low order galloping responses are prominent in the cases where the flexible cylinder is covered by fairings with large c/t. The large added mass and the low fluid force oscillation frequency in galloping are found to induce the low vibration frequency and the low order ‘lock-in’ modes in flexible cylinder responses.

Experimental investigation on vortex-induced vibration of a long-span rail-cum-road bridge with twin separated parallel decks

Long-span rail-cum-road bridges with twin separated parallel decks have become a recommended structural form because of their superior traffic capacity. However, because of inconsistent dynamic characteristics of highway and railway bridges, different wake characteristics and special aerodynamic interference between the asymmetric twin decks, the vortex-induced vibration (VIV) characteristics for twin-deck bridges are more complicated. In this paper, wind tunnel tests were carried out to study the VIV characteristics of a long-span rail-cum-road bridge with twin separated parallel decks. Furthermore, fluctuating wind pressure of the highway and railway girders was measured to discuss the vibration phenomenon. The results indicated that the VIV of the railway girder only occurs upstream, while the VIV of the highway girder occurs both upstream and downstream. The aerodynamic interference has an impact on the VIV response of both upstream and downstream girders. 3° is still the most unfavorable wind incidence angle for the twin parallel deck bridges. Increasing structural damping helps to suppress VIV, but it cannot completely suppress the occurrence of VIV. Adjusting the wind fairing angle of the highway girder and sealing the handrail at intervals are both effective in controlling VIV, but the effects are different for upstream and down girders. For the twin separated parallel decks bridges, the VIV suppression effect of the aerodynamic measures needs to be comprehensively considered from the overall consideration of the twin decks under different incoming flow directions.

The key to suppress vortex-induced vibration: Stability of the structural mode

The vortex-induced vibration (VIV) problem is common in nature and engineering fields. Current passive or active control methods try to suppress VIV by changing the flow field or improving the flow stability based on the recognition that VIV is caused by resonance. But is VIV really caused by resonance? Tuned mass damper (TMD) has been used in VIV or other vibration control for many years. However, is TMD simply an anti-resonance or energy dissipation device in VIV suppression? With the ARX(Autoregressive with exogenous input)-based reduced-order model (ROM) and the fluid–structure interaction numerical simulation, the physical mechanism of the VIV suppression with TMD in the lock-in region is investigated at a low Reynolds number (Re=60). According to the root loci, the introduction of TMD does not change the unstable wake mode, but effectively improves the stability of the structural mode. The results obtained by numerical simulation reveal that the violent vibration turns to a micro-amplitude response and the final response frequency is consistent with the vortex shedding frequency. Therefore, VIV is a stability problem rather than a dynamic response problem. Meanwhile, TMD suppresses VIV via structural mode stability enhancement rather than anti-resonance and energy dissipation. In addition, the study also found that when the TMD natural circular frequency is between 0.65 and 1.0, the vibration suppression effect is independent of the initial amplitude. This frequency range happens to be the region where the structural mode is tightly coupled with the wake mode.