A Motion Response Analysis of a Tension Leg Platform in Stokes Waves

Having deep view in structural response of tension leg platform is important issue not only for response analysis but also for engineering design. Coupling between surge and heave motions of tension leg platform is such a problem. Here, tension leg platform motions are considered only in surge and heave degrees of freedom without pitch effect. The coupled term of heave is a nonlinear differential equation. Because the focus of this article is on this term, therefore, Duffing equation of motion in the surge direction is linearized. The wave forces are calculated using Airy’s wave theory and Morison’s equation, ignoring the diffraction effects. Current force also can be very important in dynamic analysis of tension leg platform. Because it affects the term of heave that is coupled with surge. It is shown that the effect of surge motion coupling on heave motion is very important in large displacement of surge motion in many sea states. The main result is that the coupling effects appeared in some frequencies such as heave and surge frequency, twice the frequency of wave, twice the natural surge frequency, and summation and difference of frequency of wave and surge frequency.

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Motion Response Analysis of Floating Wind Turbine Combined with Wave Energy Converter

APAC 2019 ◽

10.1007/978-981-15-0291-0_150 ◽

2019 ◽

pp. 1099-1106

Author(s):

K. Chaitanya Sai ◽

Ajay H. Patil ◽

D. Karmaka

Keyword(s):

Wind Turbine ◽

Wave Energy ◽

Wave Energy Converter ◽

Response Analysis ◽

Energy Converter ◽

Motion Response ◽

Floating Wind Turbine

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Stochastic Response of Tension Leg Platform to Wave and Current Forces

Journal of Energy Resources Technology ◽

10.1115/1.3231428 ◽

1989 ◽

Vol 111 (4) ◽

pp. 221-230 ◽

Cited By ~ 5

Author(s):

A. Ertas ◽

J.-H. Lee

Keyword(s):

Constant Current ◽

Response Analysis ◽

Stochastic Dynamic ◽

Superposition Method ◽

Random Waves ◽

Stochastic Response ◽

Tension Leg Platform ◽

Single Degree Of Freedom ◽

Simulation Techniques ◽

Wave Induced

The linear analysis in the frequency domain is presented for the surge motion of a tension leg platform (TLP) in the case of random waves only and random waves with constant current. A single-degree-of-freedom model of a TLP is employed for response. The superposition method, one of the simulation techniques, is applied to random sea wave, and the response analysis of TLP in time is developed with wave velocity and wave acceleration simulations. Wave-induced forces are calculated using the modified Morison equation, which takes into account relative motion. Computational methods for both analyses are developed, and the results of stochastic, dynamic response of the TLP, with and without the presence of current, are presented and compared.

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Dynamic response analysis of a small-scale model tension leg platform

Marine Structures ◽

10.1016/0951-8339(92)90002-7 ◽

1992 ◽

Vol 5 (6) ◽

pp. 491-513 ◽

Cited By ~ 5

Author(s):

Ney Roitman ◽

Ricardo F.M. Andrade ◽

Ronaldo C. Batista

Keyword(s):

Dynamic Response ◽

Scale Model ◽

Small Scale ◽

Response Analysis ◽

Tension Leg Platform ◽

Dynamic Response Analysis ◽

Small Scale Model

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Motion response analysis for a Resonance-Free SWATH

Journal of the Japan Society of Naval Architects and Ocean Engineers ◽

10.2534/jjasnaoe.10.83 ◽

2009 ◽

Vol 10 ◽

pp. 83-96 ◽

Cited By ~ 2

Author(s):

Hajime Kihara ◽

Motoki Yoshida ◽

Hidetsugu Iwashita ◽

Takeshi Kinoshita

Keyword(s):

Response Analysis ◽

Motion Response

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A Fundamental Study on Motion Characteristics and Cargo Handling Efficiency of the Large-Scale Floating Coal Transshipment Station

Volume 6: Ocean Space Utilization ◽

10.1115/omae2018-77727 ◽

2018 ◽

Author(s):

Hiroaki Eto ◽

Yoh Shikita ◽

Tomoki Ikoma ◽

Koichi Masuda ◽

Hiroaki Kihara

Keyword(s):

Large Scale ◽

Mutual Interference ◽

Response Analysis ◽

Bulk Carrier ◽

Motion Response ◽

Cargo Handling ◽

Wave Drift ◽

Bulk Carriers ◽

Drift Force ◽

Motion Characteristics

This paper describes the motion characteristics and cargo handling efficiency of the Large-Scale Floating Coal Transshipment Station (LFTS). Indonesia is a main country supplying coal in the Asia-Pacific region, it is important to ensure a stable coal supply to Japan. Because the topography of the seabed near East Kalimantan Island, Indonesia’s main coal production area, is shallow, it is difficult for bulk carriers to reach the coast. Therefore, LFTS is proposed, which will be used as a relay base between coal-barging barges from land and bulk carriers offshore. By installing LFTS, improvement of coal transport efficiency is expected. In considering feasibility of the LFTS system, it is important to know the cargo handling operation rate in the target area, LFTS can load 500,000 tons of coal and the draft will fluctuate greatly depending on the loading condition of coal. Therefore, when the draft is shallow, the freeboard becomes large and resonates with long-term component of the wind load and when the draft is deep, the wave force and fluid force including the slowly varying wave drift force affect the fluctuation. Also, LFTS and bulk carrier are large-scale structures, the fluid forces acting on both affect each other, so the influence of hydrodynamic mutual interference between two floating bodies cannot be ignored. In this study, fluid analysis in consideration of the hydrodynamic mutual interference of LFTS system is conducted. And, response analysis of LFTS and a bulk carrier in irregular wave which considered compound external forces such as wave load and slow varying wave drift force, wind load, tidal current was performed. As a result, it was confirmed that the motion response of LFTS was not upset because LFTS was large. Therefore, without considering the motion response of the LFTS, the cargo handling efficiency is calculated from the response analysis results of the bulk carrier and the oceanic condition of the setting sea area. As a result, the cargo handling efficiency is satisfied in the state where bulk carrier is installed leeward of LFTS, and it was confirmed that the LFTS system could be operated satisfactorily if the installation was appropriate.

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Dynamic Response Analysis of a Triangular Tension Leg Platform

Volume 7: Ocean Engineering ◽

10.1115/omae2015-41480 ◽

2015 ◽

Author(s):

Qiang Guo ◽

Gang Ma ◽

Liping Sun ◽

Hongwei Wang ◽

Na Cui

Keyword(s):

Time Domain ◽

Three Dimensional ◽

Response Analysis ◽

Mooring System ◽

Preliminary Design ◽

Tension Leg Platform ◽

Operation Conditions ◽

Motion Responses ◽

Tendon Tension ◽

The Time Domain

The tension leg platform is widely used in the world. In this paper, a newly developed tension leg platform is evaluated under the environment loads of the South China Sea. The focus is on the coupling response of the platform hull and tendons. The three dimensional potential theory is used to analyze the new developed tension leg platform and its mooring system in the time domain. The new developed TLP is in a triangular-shape with three group tension legs. Every group consists of five tendons; the mooring system has been optimized after preliminary design. Coupling analysis in time domain has been conducted to evaluate its motion and tendon tension under different environmental loads. The results demonstrate the great improvement in the motion responses of this new developed TLP. The coupled motion responses of this platform with tendon lines system in extreme environmental conditions have also been evaluated in order to evaluate the safety in operation conditions.

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