Further Investigations on Vortex Self Induced Vibration (VSIV)

2011 ◽  
Author(s):  
Antonio Carlos Fernandes ◽  
Sina Mirzaei Sefat ◽  
Luis Victor Casca˜o ◽  
Pedro Vilas Boas ◽  
Ricardo Francis
Keyword(s):  
Rio De Janeiro ◽  
Horizontal Cylinder ◽  
Elastic Support ◽  
Experimental Facility ◽  
Transversal Motion ◽  
Steel Catenary Risers ◽  
Floating Platforms ◽  
Oscillating Motion ◽  
A Current ◽  
Oval Shape

An experimental facility has been designed to study the transversal and response associated with vortex-induced vibration of a totally submerged horizontal cylinder hang on horizontally elastic support under the influence of vertical harmonic oscillating motion. The study aims to analyze the vortex self induced vibration (VSIV) phenomena, which occurs for instance with Steel Catenary Risers (SRCs) the deep offshore connected to floating platforms. These vibrations occur even in the absence of a current. The experiments were conducted in a tank at the LOC/COPPE/UFRJ (Laboratory of Waves and Current of COPPE, Federal University of Rio de Janeiro). The tests were carried out with Keulegan-Carpenter numbers equal to 10 and 20 and for several exciting frequencies. The vertical trajectories of the VSIV motion were then classified based on its different configurations such as oval-shape, eight-shape and etc. Different ranges of reduced velocities were also considered. The amplitude and frequency of transversal motion and also the forces calculated.

Analysis of PIV Tests Results of the Vortex Self Induced Vibration (VSIV) of a Cylinder

2012 ◽  
Author(s):  
Antonio Carlos Fernandes ◽  
Sina Mirzaei Sefat ◽  
Luis V. Cascão ◽  
Ricardo Franciss
Keyword(s):  
Rio De Janeiro ◽  
Vertical Motion ◽  
Horizontal Cylinder ◽  
Elastic Support ◽  
Experimental Apparatus ◽  
Steel Catenary Risers ◽  
Floating Platforms ◽  
Oscillating Motion ◽  
Insight Into ◽  
Oval Shape

The Vortex Self Induced Vibration (VSIV) of cylinders is a phenomenon which occurs in the nature with devices such as Steel Catenary Risers (SRCs) in the deep offshore connected to floating platforms. The devices oscillate transversely due the own vertical motion. This is a currentless (therefore different form VIV) problem. To gain more insight into the nature of VSIV problem, an experimental apparatus was constructed which measure the transversal and response associated with vortex-induced vibration of a totally submerged horizontal cylinder hang on horizontally elastic support under the influence of vertical harmonic oscillating motion. The experiments were conducted in a tank at the LOC/COPPE/UFRJ (Laboratory of Waves and Current of COPPE, Federal University of Rio de Janeiro). The VSIV phenomena of the cylinder in different exciting amplitudes and exciting frequencies could generate different vertical trajectories of VSIV motion such as oval-shape, eight-shape and etc. This paper aims to describe the behavior of the flow around the cylinder during the VSIV motion based on the PIV tests on VSIV motion for different Keulegan-Carpenter numbers and for several exciting frequencies.

scholarly journals Health-related Quality of Life in Women with Cervical Cancer

2019 ◽  
Vol 41 (04) ◽  
pp. 242-248 ◽  
Author(s):  
Larissa dos Santos ◽  
Luciana Castaneda ◽  
Suzana de Aguiar ◽  
Luiz Thuler ◽  
Rosalina Koifman ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Cervical Cancer ◽  
Rio De Janeiro ◽  
Well Being ◽  
Health Related Quality ◽  
Simultaneous Treatment ◽  
Related Quality ◽  
Health Related ◽  
A Current

Objective To analyze the factors associated with health-related quality of life (HRQoL) in women with cervical cancer (CC) in a single center in Rio de Janeiro, state of Rio de Janeiro, Brazil. Methods A cross-sectional study in women with a diagnosis of CC followed-up in the gynecology outpatient clinic of the Hospital do Câncer II (HCII, in the Portuguese acronym) of the Instituto Nacional de Câncer (INCA, in the Portuguese acronym). The data were collected from March to August 2015. Women with palliative care, communication/cognition difficulty, undergoing simultaneous treatment for other types of cancer, or undergoing chemotherapy and/or radiation therapy were excluded. For the evaluation of the HRQoL, a specific questionnaire for women with CC was used (Functional Assessment of Cancer Therapy – Cervix Cancer [FACT-Cx]). The total score of the questionnaire ranges from 0 to 168, with higher scores indicating a better HRQoL. Results A total of 115 women were included in the present study, with a mean age of 52.64 years old (standard deviation [SD] = 12.13). The domains of emotional (16.61; SD = 4.55) and functional well-being (17.63; SD = 6.15) were those which presented the worst scores. The factors that had an association with better HRQoL in women with CC were having a current occupation, a longer time since the treatment and diagnosis, and women who had undergone hysterectomy. Conclusion Considering the domains of HRQoL of the women treated for cervical cancer, a better score was observed in the domains of physical and social/family well-being. For most domains, better scores were found between those with a current occupation, with a longer time after the diagnosis and treatment, and among those who had undergone a hysterectomy.

Steel Lazy Wave Riser Optimization Using Artificial Intelligence Tool

2020 ◽  
Author(s):  
Mayank Lal ◽  
Abhilash Sebastian ◽  
Feng Wang ◽  
Xiaohua Lu
Keyword(s):  
Artificial Intelligence ◽  
Genetic Algorithm ◽  
Design Process ◽  
Oil And Gas ◽  
Time Domain Analysis ◽  
Fatigue Performance ◽  
Wave Form ◽  
Steel Catenary Risers ◽  
Performance Drivers ◽  
Floating Platforms

Abstract Use of steel lazy wave risers has increased as oil and gas developments are happening in deeper waters or in parts of the world with no pipeline infrastructure. These developments utilize FPSO’s with offloading capabilities necessary for these developments. However, due to more severe motions compared to other floating platforms, traditional catenary form of risers are unsuitable for such developments and this is the reason Steel lazy wave risers (SLWR) are required. SLWRs have shown to have better strength and fatigue performance and lower tensions at the hang-off compared to steel catenary risers. A suitable Lazy-Wave form of the catenary riser is achieved by targeted placement of a custom configured buoyancy section. The strength and fatigue performance of steel lazy wave risers are governed by parameters such as length to start of this buoyancy section, length of the buoyancy section, hang-off angle and the buoyancy factor. Achieving these key performance drivers for a SLWR takes several iterations throughout the design process. In this paper, genetic algorithm which is an artificial intelligence optimization tool has been used to automate the generation of an optimized configuration of a steel lazy wave riser. This will enable the riser designer to speed up the riser design process to achieve the best location, coverage and size of the buoyancy section. The results that the genetic algorithm routine produces is compared to a parametric study of steel lazy wave risers varying the key performance drivers. The parametric analysis uses a regular wave time domain analysis and captures trends of change in strength and fatigue performance with change in steel lazy wave parameters.

VSIV (Vortex Self-Induced Vibration) Kinematics

2008 ◽  
Author(s):  
Antonio C. Fernandes ◽  
Erika M. C. Silva ◽  
Ricardo Franciss ◽  
Fabio M. Coelho ◽  
Severino F. S. Neto
Keyword(s):  
Graduate School ◽  
Transverse Direction ◽  
Horizontal Cylinder ◽  
Forced Oscillations ◽  
Lateral Motion ◽  
Steel Catenary Riser ◽  
The Past ◽  
Waves And Currents ◽  
Dimensional Parameters ◽  
A Current

The Vortex Induced Vibration (VIV) of cylindrical lines that may occur when the lines are submitted to currents has been extensively discussed in the past few years and its behavior has become well known. However, it is not so well known that the vibrations may occur in a current-less situation, induced by the lateral motion of the structure itself. The present work refers to the last as the Vortex Self-Induced Vibration, the VSIV. This occurrence has been made clear in the LOC/COPPE/UFRJ (Laboratory of Waves and Currents of COPPE, the Graduate School of Federal University of Rio de Janeiro) by specifically designed tests. In these tests, a totally submerged horizontal cylinder was submitted to harmonic forced oscillations, being free to move in the transverse direction of the forced excitation. The VSIV then showed up, with the cylinder segment, describing vertical trajectories in two (vertical 8-shape), three, four, etc., almost circular trajectories (called the rings in the work). Subsequently, the work shows that the measurements in full scale with the VIV bottle on a Steel Catenary Riser in the PETROBRAS 18 platform also indicate the existence of the VSIV. The tests were carried out with Keulegan-Carpenter equal to 10, 20 and 30 and for several amplitudes. The response of the cylinder was represented in non-dimensional parameters corresponding to the amplitude, the excitation and the response frequencies.

Development and Qualification of Alternative Solutions for Improved Fatigue Performance of Deepwater Steel Catenary Risers

2007 ◽  
Author(s):  
Rajiv K. Aggarwal ◽  
Marcio M. Mourelle ◽  
Steinar Kristoffersen ◽  
Henri Godinot ◽  
Pedro Vargas ◽  
...  
Keyword(s):  
Laboratory Testing ◽  
Fatigue Testing ◽  
High Strength ◽  
Operating Conditions ◽  
Fatigue Performance ◽  
Steel Catenary Riser ◽  
Regulatory Bodies ◽  
Steel Catenary Risers ◽  
Floating Platforms ◽  
Floating Systems

Several initiatives have been undertaken by the operators, engineering companies, product manufacturers, and regulatory bodies to enable increased use of steel catenary riser (SCR) design in development of deepwater and ultra-deepwater fields. Some of these efforts focus on improvement in understanding of soil-structure interaction at SCR touch down zone (TDZ) and its impact on fatigue damage estimates through analytical studies, laboratory testing, or in-field monitoring of SCR behavior. Through recent studies and laboratory testing work for floating platforms with SCR, the need for significant enhancement of SCR design at TDZ through implementation of alternate solutions has been identified. This paper presents a summary of the work undertaken in a Joint Industry Project (JIP) during 2004 to 2007 [1, 2] to develop solutions and undertake qualification tasks for four alternatives with potential to improve fatigue performance at TDZ by factor of up to 10 or more. The solutions considered at SCR TDZ include: thick light-weight coating over steel riser sections; steel riser sections with upset ends; high strength steel riser sections with integral connectors; and a titanium segment. The major qualification tasks undertaken for each solution will be identified and discussed. The qualification program undertaken for each solution varied and in some cases, it also included manufacturing of samples, laboratory and full-scale fatigue testing, and post-failure evaluation. Through significant qualification activities undertaken in this JIP, progress has been made to bring these solutions to project ready state for their consideration at the frond end engineering design (FEED) stage. Such design enhancements would enable increase in selection of SCR design for production and export riser applications under severe operating conditions, harsh environment, and floating systems with high motions.

New Design Configuration of Steel Catenary Risers With Pull-Tube for Spars

2011 ◽  
Author(s):  
Shan Shi ◽  
Charlie Mao ◽  
Jenny Yang ◽  
Nishu Kurup
Keyword(s):  
Finite Element ◽  
Finite Element Program ◽  
Additional Advantage ◽  
Nonlinear Contact ◽  
Element Program ◽  
Steel Catenary Risers ◽  
Bending Loads ◽  
A Current ◽  
Water Depths ◽  
Over Time

In previous Spar designs where pull tubes were used to board the risers (either export or flowline risers), the pull-tube extended a considerable distance beyond the keel and used a tapered design to form a bend restrictor that supported the riser throughout the riser/hull interface. In a current Spar design, the pull-tube is terminated at the hull keel and the bending loads are carried by a double sided stress-joint in the riser that pivots on a centralizer located near the bottom of the pull-tube. Essentially, this is an adaptation of the double-sided stress joint used for top tensioned risers exiting the bottom of their buoyancy can stems to the similar condition of an SCR exiting a pull tube terminating at the Spar’s keel. This new pull-tube and SCR configuration can be applied for both Truss and Classic Spars. SCRs boarding Spars through pull tubes have several advantages over stress joints or flex-joints anchored in porches, notably, eliminating both the need for divers to make large piping connections at 500′ to 600′ water depths and the possibility of those connections leaking over time. Moving the bend restrictor function from the pull tube to the riser provides the additional advantage of adding flexibility for the Spar to accommodate future risers whose size and weight are not known at the time the pull tubes are designed and the platform is installed. With the stress joint as part of the riser, the bend restrictor can be custom designed for each riser since the pull tube works the same for all risers. The SCR and stress joint, pull-in and in-place analyses have been performed by using the finite element program ABAQUS. The nonlinear capabilities of ABAQUS including the hybrid, gap and contact element formulations are utilized in the analysis of the pull-in process. The nonlinear contact elements with finite sliding capability are modeled with an exponential over-closure relationship.

Sleeved Stress Joint for Steel Catenary Riser Application

2010 ◽  
Author(s):  
S.-H. Mark Chang ◽  
Paul Stanton ◽  
Sunil Kuriakose ◽  
Hugh Thompson
Keyword(s):  
Bending Moment ◽  
Variable Stiffness ◽  
Floating Platform ◽  
Steel Catenary Riser ◽  
High Fatigue ◽  
Steel Catenary Risers ◽  
Design Requirements ◽  
Floating Platforms ◽  
Oil Gas ◽  
Economical Alternative

Steel catenary risers (SCRs) have been widely used for oil/gas/water transport on floating platforms for the last fifteen years. Flex joints and tapered stress joints are often used for interface between the SCR and platform. Flex joints and tapered stress joints need to be designed to meet both the stiffness and flexibility requirements. A stress joint requires high stiffness to withstand the bending moment induced by the SCR and at the same time needs to be sufficiently flexible so as not to overstress the SCR. To achieve these complex requirements, a sleeved stress joint (SSJ) provides a sound technical and economical alternative for the interface between the SCR and platform. A sleeved stress joint utilizes multiple pipes to provide variable stiffness and to meet the strength and flexibility requirements. In the design of a SSJ, the number of sleeves, and the outer diameters and wall thicknesses of the sleeved pipes can be adjusted to achieve the design requirements. In addition, the locations of welds in the sleeved pipes can be placed to achieve the high fatigue performance that is important in stress joint design. Feasibility of the SSJ design is verified through state-of-the-art computer modeling. Generic cases of SSJ design applied to the porch and pull tube of a floating platform are presented. The design concept is compared with traditional flex joint and tapered stress joint designs. The technical and economic advantages of such a design are discussed.

A Parametric Study on Effects of Environmental Loadings on Fatigue Life of Steel Catenary Risers (Using a Nonlinear Cyclic Riser-Soil Interaction Model)

2010 ◽  
Author(s):  
Mehrdad Kimiaei ◽  
Mark Randolph ◽  
Ivan Ting
Keyword(s):  
Fatigue Damage ◽  
Deep Water ◽  
Interaction Model ◽  
Fatigue Assessment ◽  
Wide Range ◽  
Non Linear ◽  
Wave Heights ◽  
Steel Catenary Risers ◽  
Vessel Motion ◽  
Floating Platforms

Steel catenary risers (SCRs) are often the preferred option for subsea tie-back to floating platforms in deep water due to their conceptual simplicity, ease of construction and installation and simple interface with the flowlines. Fatigue design of SCRs, particularly in the touch down area (TDA), has always been one of the major engineering challenges. Traditionally, fatigue assessment of SCRs has usually been highly conservative, because of lack of precise understanding of the non-linear soil-riser-interaction in the TDA. Most fatigue studies are based on assumed linear stiffness for the seabed, partly because of the lack of robust non-linear riser-seabed interaction models and partly because the linear response simplifies the fatigue study. The recent availability of non-linear seabed response models provides an opportunity to improve fatigue assessment, but it is first necessary to evaluate how best to conduct fatigue studies for such nonlinear systems which can be sensitive to wide range of input parameters. This paper outlines a new advanced numerical model, considering nonlinear cyclic riser-soil interaction behavior, used to determine the contribution of different loading parameters on fatigue damage of SCRs in the TDA in deep water soft sediments. The main loading parameters considered are: different motions of floating vessels, wave heights, wave periods and wave packs ordering. Numerical modeling has shown that over 95% of the fatigue damage corresponds to floating vessel motion parallel to the riser axis at the connection point to the vessel. It is also shown that riser response at TDA is highly influenced with amplitude and period of the environmental loadings.

scholarly journals SIMULTANEOUS WAVE AND CURRENT FORCES ON A PIPELINE

1980 ◽  
Vol 1 (17) ◽  
pp. 106
Author(s):  
David A. Knoll ◽  
John B. Herbich
Keyword(s):  
Small Diameter ◽  
Horizontal Cylinder ◽  
Random Wave ◽  
Ocean Bottom ◽  
Hydrodynamic Loads ◽  
Fluid Force ◽  
Interaction Of Waves ◽  
Drag Forces ◽  
Waves And Currents ◽  
A Current

The hydrodynamic loads on an offshore pipeline resting on the ocean bottom are a function of parameters associated with waves and currents acting near the pipeline. There have been many studies conducted to develop the criteria needed to estimate the hydrodynamic loads imposed by waves and currents. Many of these studies have investigated the effect of these phenomena individually, but to date only limited research has been directed towards evaluating the combined effect. In general, the investigations of the interaction of waves and currents and their effect on the fluid force have been directed toward vertical piles1'2'3'1*'5 and structures in a random wave field with a current present;6'7'8'9 however, the fluid force of waves in the presence of currents on pipelines has not been directly addressed. The purpose of this research was to investigate the interaction of waves and currents and its relationship to the forces on submerged pipelines. A model pipeline in a wave-flume was used to obtain experimental values which were compared to values predicted by the Morison equation in conjunction with the superposition of the waves and a current. The Morison equation10 was used to evaluate the forces on a horizontal cylinder resting on the bottom. The two major input parameters required by this equation are (1) the water particle kinematics of velocity and acceleration; and (2) the coefficients of drag and inertia. The testing program investigated the drag forces developed by the combined waves and a current. The inertia forces were assumed small when compared to the drag forces since a relatively small diameter cylinder was used in the experiments, thus the accelerations were small.

Time-Domain Calculations of Drift Forces on Floating Two-Dimensional Object in Current and Waves

1994 ◽  
Vol 38 (02) ◽  
pp. 97-103
Author(s):  
H. J. Prins ◽  
A. J. Hermans
Keyword(s):  
Added Mass ◽  
Horizontal Cylinder ◽  
Second Order ◽  
Floating Body ◽  
Infinite Length ◽  
Two Dimensional ◽  
Damping Coefficients ◽  
Dimensional Object ◽  
A Current ◽  
Drift Forces

In this paper the influence of a current on the drift forces acting on a floating body is studied. A theory has been developed which is correct up to second-order in the current velocity. A numerical algorithm has been found which solves the time-dependent equations and is stable for all current velocities. To test this algorithm, a two-dimensional case has been studied, i.e., the drift forces on a horizontal cylinder of infinite length. A computer program has been developed and very encouraging results have been found for the added-mass and damping coefficients and the drift forces. It is shown that especially for higher velocities the second-order terms in the velocity become very important.

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