Model Test of a Steel Catenary Riser in a Towing Tank

2009 ◽  
Author(s):  
Celso K. Morooka ◽  
Raphael I. Tsukada ◽  
Sergio da Silva ◽  
Ricardo Franciss ◽  
Cyntia G. C. Matt
Keyword(s):  
Model Test ◽  
Forced Oscillation ◽  
Cross Flow ◽  
Towing Tank ◽  
Steel Catenary Riser ◽  
Flow Response ◽  
Numerical Predictions ◽  
Steel Catenary Risers ◽  
Numerical Tools ◽  
Scr Model

The objective of the present work is the study of the dynamic behavior of steel catenary risers (SCRs), focusing on the contribution of vortex-induced vibration (VIV), through model test in a towing tank. Nowadays, a great deal of effort is being spent in order to better understand VIV’s contribution in the dynamics of riser structures through experiments, analytical analysis and numerical predictions. In the present work, the design of a SCR model test, along with its setup in a towing tank, will be described in detail and discussions of main results from the experiments will be presented. The experiment has been conducted under several simulated environmental condition combinations, varying the towing speed, riser top forced oscillation amplitudes, waves amplitudes and periods. Very promising results have been observed from the experiment. Riser oscillations due to high harmonics of vortex shedding were observed. Analysis of the experimental results, coupled with the support of numerical tools, showed the influence of the phenomena of traveling waves in the cross-flow response as is reported from the literature.

Model Test on Drag of Cylinders With Helical Grooves at High Reynolds Numbers

2010 ◽  
Author(s):  
Shan Huang ◽  
Neil Kitney
Keyword(s):  
Model Test ◽  
Cross Flow ◽  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Tank Model ◽  
Towing Tank ◽  
High Reynolds Numbers ◽  
High Reynolds ◽  
Helical Grooves ◽  
Four Cylinders

Towing tank model tests at high Reynolds numbers, up to 1.1×106, were carried out in order to investigate the effects of the triple-starting helical grooves on drag reduction of smooth and rough circular cylinders in uniform cross flow. In total, four cylinders were tested including smooth and rough cylinders with and without helical grooves.

A Truss Semisubmersible Optimized for the Post Katrina Environment in Gulf of Mexico Correlated With Model Test

2009 ◽  
Author(s):  
Chan K. Yang ◽  
John Murray ◽  
Hanseong Lee ◽  
Myoungkeun Choi ◽  
Cheng-Yo Chen ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Model Test ◽  
Oil And Gas ◽  
Vertical Motion ◽  
Scale Model ◽  
Natural Period ◽  
Steel Catenary Riser ◽  
Numerical Predictions ◽  
Wave Basin ◽  
Global Performance

This paper presents a Truss Semisubmersible (Truss Semi) design optimized to meet the post-Katrina Gulf of Mexico (GoM) environment criteria, with global performance correlated in 1:50 scale model tests in a wave basin. A conventional semisubmersible with a ring pontoon is facilitated with heave plates supported by the truss structure to increase heave natural period. The size of the semisubmersible hull and the configuration of the heave plates are optimized through frequency domain analysis to minimize the vertical motion enough to allow the dry trees to accommodate top tensioned production risers. The system includes eight production top tension risers (TTRs) connected to the production deck and a single drilling riser connected to the drilling deck. All of the TTRs are connected through the hydro-pneumatic tensioner system. One gas export and one oil export steel catenary riser (SCR) export the oil and gas to the storage facility. Structures designed for this deepwater area (4,300 ft) of the central Gulf of Mexico (GoM) must be designed to meet newly proposed environmental criteria [1]. The optimized Truss Semi was tested in the Offshore Technology Research Center (OTRC) model basin, to confirm the global performance, such as motion, air gap and loads on the heave plates. The numerical predictions correlate well with the model test results.

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.

UJI TARIK HIDRODINAMIKMODEL KAPAL BERSAYAP WiSE DENGAN LAMBUNG DASAR BERSTEP

2013 ◽  
Vol 12 (3) ◽  
Author(s):  
Iskendar Iskendar ◽  
Andi Jamaludin ◽  
Paulus Indiyono
Keyword(s):  
Comparative Study ◽  
Model Test ◽  
Hydrodynamic Model ◽  
Surface Effect ◽  
Center Of Gravity ◽  
Test Results ◽  
Flat Bottom ◽  
Towing Tank ◽  
Test Models ◽  
Wetted Surface Area

This paper describes hydrodynamic model tests of Wing in Surface Effect (WiSE) Craft. These craft  was fitted with  stephull  form in different location on longitudinal flat bottom (stepedhull planning craft) to determine the influences of sticking and porpoising motion performances. These motions are usually occured when the craft start to take-off from water surfaces. The test models with scale of 1 : 7 were comprised of 4 (four) stephull models and 1 (one) non-stephull model  as a comparative study. The hydrodynamic  tests were performed with craft speed of 16 – 32 knots (prototype values) in Towing Tank at UPT. Balai Pengkajian dan Penelitian Hidrodinamika (BPPH), BPPT, Surabaya. The resistance (drag) was measured by dynamo meter and the trim of model (draft changing at fore and aft  of model due to model speed) was measured by trim meter. By knowing the value of model trim, the wetted surface area can be determined. Then, the lift forces were calculated based on these measured values. The model test results were presented on tables and curves.  Test results show that models  with step located far away from center of gravity of the WiSE craft tend to porpoising and sticking condition, except if the step location on the below of these center of gravity. While model without step tends to sticking conditions.

Dynamic Optimization of Steel Catenary Risers Based on Reliability Using Metamodel

2010 ◽  
Author(s):  
Wenqing Zheng ◽  
Hezhen Yang
Keyword(s):  
Dynamic Optimization ◽  
Computational Cost ◽  
Minimum Cost ◽  
Probabilistic Constraints ◽  
Optimization Approach ◽  
Element Analysis ◽  
Steel Catenary Riser ◽  
Reliability Based Design ◽  
Minimum Cost Design ◽  
Steel Catenary Risers

Reliability based design optimization (RBDO) of a steel catenary riser (SCR) using metamodel is investigated. The purpose of the optimization is to find the minimum-cost design subjecting to probabilistic constraints. To reduce the computational cost of the traditional double-loop RBDO, a single-loop RBDO approach is employed. The performance function is approximated by using metamodel to avoid time consuming finite element analysis during the dynamic optimization. The metamodel is constructed though design of experiments (DOE) sampling. In addition, the reliability assessment is carried out by Monte Carlo simulations. The result shows that the RBDO of SCR is a more rational optimization approach compared with traditional deterministic optimization, and using metamodel technique during the dynamic optimization process can significantly decrease the computational expense without sacrificing accuracy.

Mitigation of Vortex-Induced Motions in a Monocolumn Platform

2009 ◽  
Author(s):  
Andre´ L. C. Fujarra ◽  
Rodolfo T. Gonc¸alves ◽  
Fernando Faria ◽  
Marcos Cueva ◽  
Kazuo Nishimoto ◽  
...  
Keyword(s):  
Model Test ◽  
Numerical Models ◽  
Cross Flow ◽  
Important Data ◽  
Data Set ◽  
Concept Model ◽  
Flow Motion

A great deal of works has been developed on the Spar VIM issue. There are, however, very few published works concerning VIM of monocolumn platforms, partly due to the fact that the concept is fairly recent and the first unit was only installed last year. In this context, the present paper presents a meticulous study on VIM for this type of platform concept. Model test experiments were performed to check the influence of many factors on VIM, such as different headings, wave/current coexistence, different drafts, suppression elements, and the presence of risers. The results of the experiments presented here are inline and cross-flow motion amplitudes, ratios of actual oscillation and natural periods, and motions in the XY plane. This is, therefore, a very extensive and important data set for comparisons and validations of theoretical and numerical models for VIM prediction.

Experiments with a steel catenary riser model in a towing tank

2013 ◽  
Vol 43 ◽  
pp. 244-255 ◽  
Author(s):  
Celso K. Morooka ◽  
Raphael I. Tsukada
Keyword(s):  
Towing Tank ◽  
Steel Catenary Riser

Sensitivity Study of Critical Parameters Influencing the Uncertainty of Fatigue Damage in Steel Catenary Risers

2010 ◽  
Author(s):  
Feng Zi Li ◽  
Ying Min Low
Keyword(s):  
Fatigue Damage ◽  
Cost Effective ◽  
Sensitivity Study ◽  
Structural Safety ◽  
Critical Parameters ◽  
Design Parameters ◽  
Steel Catenary Riser ◽  
Bending Stresses ◽  
Steel Catenary Risers ◽  
Touchdown Point

The most challenging aspect of a deepwater development is the riser system, and a cost-effective choice is the Steel Catenary Riser (SCR). Fatigue is often a governing design consideration, and it is usually most critical at the touchdown point (TDP) where static and dynamic bending stresses are highest. Unfortunately, it is also at this region that uncertainty is the maximum. The increased uncertainty casts doubt on the applicability of generic safety factors recommended by design codes, and the most consistent way of ensuring the structural safety of the SCR is to employ a reliability-based approach, which has so far not received attention in SCR design. As the number of basic random variables affects the complexity of a reliability analysis, these variables should be selected with caution. To this end, the aim of this paper is to draw up a comprehensive list of design parameters that may contribute meaningfully to the uncertainty of the fatigue damage. From this list, several parameters are selected for sensitivity studies using the commercial package Orcaflex. It is found that variations in seabed parameters such as soil stiffness, soil suction and seabed trench can have a pronounced influence on the uncertainty of the fatigue damage at the touchdown point.

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