Analysis of vortex induced vibrations of marine risers

Vortex induced vibrations (VIV) can be a severe problem to marine risers with regard to fatigue damage and drag loading. In order to design marine risers, therefore, it is necessary to have good theoretical and numerical models for prediction of VIV. Full-scale data are needed for verification of th...

Full description

Saved in:
Bibliographic Details
Published inModeling, identification and control Vol. 24; no. 2; pp. 71 - 85
Main Authors KAASEN, Karl E, LIE, Halvor
Format Journal Article
LanguageEnglish
Published Oslo Research Council of Norway 01.04.2003
Norsk Forening for Automatisering (NFA)
Norwegian Society of Automatic Control
Subjects
Applied sciences
Computer science; control theory; systems
Control theory. Systems
Exact sciences and technology
Least Squares Estimation
Miscellaneous
Modal Analysis
Vortex Induced Vibration. Marine Risers
Energy analysis
Statistical analysis
Vibration
Modal analysis
Fast Fourier transformation
Estimation
Fatigue
Marine
Drag
Least squares method
Accelerometer
Vortex
Riser
Damaging
Gravity
Online AccessGet full text

Cover

More Information
Summary:Vortex induced vibrations (VIV) can be a severe problem to marine risers with regard to fatigue damage and drag loading. In order to design marine risers, therefore, it is necessary to have good theoretical and numerical models for prediction of VIV. Full-scale data are needed for verification of the models. To this end, three drilling risers were instrumented with accelerometers and rotation-rate devices for measurement of VIV. Also, sea current was measured at number of depths for reference. A large quantity of data was collected during the time the instrument system was in operation. In order to choose data records for further investigation and comparison with theoretical models the raw data had to be conditioned and converted to a suitable form. The paper describes how the riser lateral displacements were derived from the measurements. A major task has been to rid the acceleration measurements of the influence of gravity due to the riser's rotations out of the vertical and include the measurements of angular motion in a consistent way. This has been done using modal decomposition and a least-squares method combined with frequency-domain calculation to estimate the modal weights. MATLAB was used for the calculations and the presentation of results. An example of results is given.
ISSN:0332-7353
1890-1328
DOI:10.4173/mic.2003.2.1