Dynamic behaviors of conventional SCR and lazy-wave SCR for FPSOs in deepwater

Kim, Seungjun; Kim, Moo-Hyun

doi:10.1016/j.oceaneng.2015.06.039

Cited by 45 publications

(14 citation statements)

References 14 publications

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“…Thus, [16] described R and Q as model-specific "tuning knobs" that determine filter performance and expressed choosing them as "spirit of observer design". First, P 1 was set large enough to make the initial convergence fast, as Equation (18). This is because the initial state is uncertain.…”

Section: Main Formulas For Inverse Wave Estimationmentioning

confidence: 99%

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Real-Time Inverse Estimation of Ocean Wave Spectra from Vessel-Motion Sensors Using Adaptive Kalman Filter

2019

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The real-time inverse estimation of the ocean wave spectrum and elevation from a vessel-motion sensor is of significant practical importance, but it is still in the developing stage. The Kalman-filter method has the advantages of real-time estimation, cost reduction, and easy installation than other methods. Reasonable estimation of high-frequency waves is important in view of covering various sea states. However, if the vessel is less responsive for high-frequency waves, amplified noise may occur and cause overestimation problem there. In this paper, a configuration of Kalman filter with applying the principle of Wiener filter is proposed to suppress those over-estimations. Over-estimation is significantly reduced at high frequencies when the method is applied, and reliable real-time wave spectra and elevations can be obtained. The simulated sensor data was used, but the proposed algorithm has been proved to perform well for various sea states and different vessels. In addition, the proposed Kalman-filter technique is robust when it is applied to time-varying sea states.

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Section: Main Formulas For Inverse Wave Estimationmentioning

confidence: 99%

“…The total number of 1831 quadrilateral panels was used after the convergence test. The details of the vessel are given in [18]. Figure 5 is the RAO of the FPSO.…”

Section: Main Formulas For Inverse Wave Estimationmentioning

confidence: 99%

Real-Time Inverse Estimation of Ocean Wave Spectra from Vessel-Motion Sensors Using Adaptive Kalman Filter

2019

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“…The finite element (FE) model of the nonlinear HPT and the floating platform motion is implemented in CHARM3D, a fully-coupled time-domain dynamic-analysis program for floating bodies, mooring lines/tendons, and risers (Ran 2000, Koo et al 2004, Yang and Kim 2011, Kang and Kim 2012, Bae and Kim 2013, Kang et al 2013, Kang et al 2014, Kim and Kim 2015. The frequency-dependent hydrodynamic coefficients and the first-order and second-order wave excitation forces and moments are calculated by the near-field method by using WAMIT (Lee and Newman 1991), a diffraction/radiation panel program.…”

Section: Modeling Of Coupled Dynamics Of Platform Riser and Hpt Undementioning

confidence: 99%

Tension variations of hydro-pneumatic riser tensioner and implications for dry-tree interface in semisubmersible

Kang

Kim

Aramanadka

2017

Ocean Systems Engineering

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In real sea environments, excessive dynamic axial tension variations can be exerted on the toptensioned risers (TTRs) and lead to structural integrity issues. The traditional riser-tension-variation analysis, however, by using parametric formulation is only conditionally valid under certain strict limits and potentially underestimates the total magnitudes of tension variations. This phenomenon is especially important for the long stroke tensioner in dry-tree semisubmersible with larger global heave motion and longer stroke. In this paper, the hydro-pneumatic tensioner (HPT) is modeled in detailed component-level which includes a set of hydraulic and pneumatic components. The viscous fluid frictional effect in the HPT is considered. The main objectives are (i) to develop a detailed tension variation model of the HPT; (ii) to identify the deviations between the conventional parametric formulation and component-level formulation; (iii) to numerically analyze the tension variation of long stroke tensioner in a dry-tree semisubmersible (DTS). The results demonstrate the necessity of component-level formulation for long stroke tensioner in the development of DTS.

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“…In marine environment, offshore steel pipes (e.g. rigid risers) bear dynamic loads long-termly generated by wave, current, wind, and 2nd order floater motions (Kim and Kim 2015;Chibueze et al 2016;Li et al 2019). The cyclic bending loads, as one of the dominate load cases, is frequently applied on fatigue critical zones such as hang-off zone, sag bend, arch bend and the touch down zone.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis on the SIF of internal surface cracks in steel pipes reinforced with CRS subjected to bending

Jiang

Hopman

2019

Ships and Offshore Structures

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In this paper, Composite Repair System (CRS) is applied to repair the circumferential internal surface cracked steel pipes subjected to bending. The Stress Intensity Factor (SIF) is quantitatively analysed by means of numerical simulations, and the crack growth rate is predicted by using the Paris' law. First, the three-dimensional finite element (FE) model is developed, and its reliability of evaluating SIF of internal surface crack in CRS reinforced pipe is validated. Then based on the FE method and combined with Paris' law, a case study is deployed to predict the internal surface crack growth in steel pipes reinforced with CRS. The results show that CRS have significantly reduced the SIF of the internal surface crack and decrease the crack growth rate, while unchanging the variation trend of the crack aspect ratio. Afterwards, a parametric study is performed in order to guide the optimisation design of CRS reinforcement.

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Dynamic behaviors of conventional SCR and lazy-wave SCR for FPSOs in deepwater

Cited by 45 publications

References 14 publications

Real-Time Inverse Estimation of Ocean Wave Spectra from Vessel-Motion Sensors Using Adaptive Kalman Filter

Real-Time Inverse Estimation of Ocean Wave Spectra from Vessel-Motion Sensors Using Adaptive Kalman Filter

Tension variations of hydro-pneumatic riser tensioner and implications for dry-tree interface in semisubmersible

Numerical analysis on the SIF of internal surface cracks in steel pipes reinforced with CRS subjected to bending

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