Improved Strake Design for Vortex Induced Motions of Spar Platforms

Irani, Mehernosh; Finn, Lyle

doi:10.1115/omae2005-67384

Cited by 15 publications

(10 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The tests are conducted by pulling the model and taking motion and drag measurement. Details of the experimental setup can be obtained from [4]. The model tests [4] were done for several current headings with different inflow current speeds.…”

Section: Model Testsmentioning

confidence: 99%

“…Details of the experimental setup can be obtained from [4]. The model tests [4] were done for several current headings with different inflow current speeds. The operating Reynolds numbers were in the range of 70,000 to 200,000.…”

Section: Model Testsmentioning

confidence: 99%

“…Rigorous experiments on scaled down spar models are frequently conducted to study their response. One such experiment series is documented in [4]. The model used was scaled at 1:40 (Froude scale) of an actual Truss Spar.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

CFD Simulation of Truss Spar Vortex-Induced Motion

Atluri

Halkyard

Sirnivas

2006

Volume 4: Terry Jones Pipeline Technology; Ocean Space Utilization; CFD and VIV Symposium

View full text Add to dashboard Cite

Helical strakes are used to suppress the Vortex-Induced Motion of Truss Spars. Model experiments have demonstrated the efficiency of strakes in the Truss Spar design but also indicate that the VIM response is sensitive to the details of strake design and placement of appurtenances around the Spar hull. It is desirable to study these hydrodynamic effects using CFD. The following paper is a continuation of some of the earlier CFD simulations on this subject (see, J. Halkyard, et al., "Benchmarking of Truss Spar Vortex-Induced Motions Derived from CFD with Experiments", Proceedings of OMAE'05). This paper in particular deals with the effect of holes in the strakes and appurtenances and their placement. All the simulations were done at model scale (1:40 scale model of an actual Truss Spar design) to compare the motions with experimental results. Mesh sensitivity and turbulence modeling issues are also discussed. Calculations were done using general purpose CFD code Acusolve TM .

show abstract

Section: Model Testsmentioning

confidence: 99%

Section: Model Testsmentioning

confidence: 99%

See 1 more Smart Citation

CFD Simulation of Truss Spar Vortex-Induced Motion

Atluri

Halkyard

Sirnivas

2006

Volume 4: Terry Jones Pipeline Technology; Ocean Space Utilization; CFD and VIV Symposium

View full text Add to dashboard Cite

show abstract

“…We study the vortex-induced motions of bare cylinders and straked cylinders using computational fluid dynamics (CFD) tools. The cylindrical structures used here resemble the hard tank of a truss spar model described by Irani and Finn (2005). A companion paper by Halkyard et al (2005) provides the benchmark study of CFD with model experiments, as well as examines the influence of current direction on the VIM of straked cylinders.…”

Section: Omae2005-67263mentioning

confidence: 99%

“…The latter can have implications on the mooring loads for a spar platform. Irani and Finn (2005) have conducted model tests on a truss spar platform with different strake configurations. They conclude that the geometry and orientation of strakes can be optimized for maximum performance.…”

Section: Introductionmentioning

confidence: 99%

CFD Analysis of Vortex-Induced Motions of Bare and Straked Cylinders in Currents

Thiagarajan

Constantinides

Finn

2005

24th International Conference on Offshore Mechanics and Arctic Engineering: Volume 3

View full text Add to dashboard Cite

It is widely acknowledged that the use of helical strakes for mitigation of vortex-induced motions (VIM) of surface piercing cylinders, such as spar platforms, is only partially effective. Using computational fluid dynamics tools, we compare the oscillation characteristics of a bare cylinder and a straked cylinder in uniform currents.Our model comprised of a straked cylinder with diameter of 0.741 m, aspect ratio of 1:1.9 and three helical strakes of height 13% of cylinder diameter. This geometry corresponds to the hard tank geometry of a scaled truss spar model known to exhibit VIM in tow tank testing. In the CFD simulations the cylinder is moored with linear springs to provide a range of reduced velocities.The fluid domain is made of an unstructured grid comprising of hexahedral elements. Fluid structure interaction utilizes grid stretching and a user defined function for solving the equations of motion. Turbulence modeling uses Detached Eddy Simulation (DES) and the boundary layer is modeled using a wall function with a surface roughness of 0.0003 m. Reynolds numbers are in the range of 50,000 to 100,000.Results for straked cylinder compares reasonably with published results, but under-predicts the peak response. In comparing with corresponding results for a bare cylinder without strakes, the spectral features of the transverse displacement show variations, which are found to be due to the spoiling effect of the strakes.

show abstract

Experimental and numerical studies of the pontoon effect on vortex-induced motions of deep-draft semi-submersibles

Liu

Xiao

Liang

et al. 2017

Journal of Fluids and Structures

View full text Add to dashboard Cite

The vortex-induced motion (VIM) is a critical issue in mooring and riser system design for column-type deepwater platforms. As regards to deep-draft semi-submersibles (DDS), even though VIM is mainly excited by vortex shedding around columns, the large-volume pontoons beneath the columns are also responsible for the wake interference, implying a non-negligible influence on VIM behavior. An experimental study and three-dimensional numerical simulations were performed to analyze the pontoon effect on the VIM of two semi-submersibles and a four-column structure without pontoons. The numerical results using Detached Eddy Simulation (DES) are in good agreement with the experimental measurements obtained from the towing model tests. The present investigations indicate that the resonant phenomenon is observed for all configurations. However, the four-column structure without pontoons shows the most significant transverse responses and yaw motions at both 0°- and 45°-incidences owing to the largest fluctuating lift forces induced by the well-established wake. Additionally, the negative values of work done by the pontoons at all reduced velocities confirm their damping effect on the VIM response

show abstract

Improved Strake Design for Vortex Induced Motions of Spar Platforms

Cited by 15 publications

References 0 publications

CFD Simulation of Truss Spar Vortex-Induced Motion

CFD Simulation of Truss Spar Vortex-Induced Motion

CFD Analysis of Vortex-Induced Motions of Bare and Straked Cylinders in Currents

Experimental and numerical studies of the pontoon effect on vortex-induced motions of deep-draft semi-submersibles

Contact Info

Product

Resources

About