Monocolumn behavior in waves: Experimental analysis

Sphaier, Sergio H.; Torres, Fernando Gómez; Masetti, Isaias Quaresma; Costa, Ana Paula; Levi, Carlos

doi:10.1016/j.oceaneng.2006.10.017

Cited by 40 publications

(9 citation statements)

References 3 publications

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“…The problem has been identified for a broad number of practical applications. Sphaier et al [4] shows that the heave motions of a new platform concept, the Monocolunm Production, Storage and Offloading system (MPSO) [5], are significantly affected by the moonpool design. In Chen et al [3] the problem is presented for side-by-side offloading operations.…”

Section: The Moonpool Effectsmentioning

confidence: 99%

The Dynamic Effects of Water Column Inside the Turret of an FPSO

2013

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Thanks to the evolution of hardware and software, the direct computation of dynamic loads is becoming a common practice on the design of offshore floating units for both extreme and fatigue assessments. In the specific case of FPSOs, usually the loads prescribed by Classification Societies for oil tankers are adopted. Nevertheless, the direct computation may be used in order to adapt those prescribed extreme loads to consider the specific operational profile of FPSOs. Also the performance of spectral fatigue analysis is commonly accepted in lieu of the Rules prescriptions. The state-of-the-art is to employ potential theory for the hydrodynamic calculations. In this theory, the fluid is considered ideal and therefore no viscous dissipation is included. In spite of the reasonable accuracy of that theory for the computation of large bodies' behavior, in the case of FPSOs with internal turret it may overpredict the free surface elevation inside the turret around resonance frequencies, which may impact both global and local loads acting on the hull. In reality, however, it is expected that a lot of dissipation is generated by the turret structure and components which would bring the wave elevation to much lower levels. In this paper, the relevance of the phenomenon for the structural assessment of an FPSO is evidenced and the effects of dissipation are discussed based on modified potential theory results and CFD RANS analysis. Nomenclature FPSO Floating Production Storage and Offloading CFDComputational Fluid Dynamics RANS Reynolds-Averaged Navier Stokes

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Section: The Moonpool Effectsmentioning

confidence: 99%

The Dynamic Effects of Water Column Inside the Turret of an FPSO

2013

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“…The moonpool bottom of the truss spar platform or the monocolumn hull were changed to reduce the adverse motions. 17–21 The recess structure, baffle and appendage were installed in the moonpool. 22–25 The doors, the flaps, the cut-out parts and the wedge were arranged in the moonpool to reduce the ship resistance.…”

Section: Introductionmentioning

confidence: 99%

Reducing bubble generation and sweepdown effect on a research vessel with a moonpool

Yao

Huang

Shi

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part M:

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Some research vessels set moonpools for sonars installation. The moonpool provides a relatively good working environment for sonar in a harsh marine environment. At the same time, other acoustic detection equipment are installed along the ship bottom behind the moonpool. Due to the exist of the sonar with a variable cross-section, the number of bubbles generated in the moonpool increases. The bubbles generated in the moonpool expel and flow along the vessel bottom to the stern, which leads to the sweepdown effect. The performance of the sonar and other acoustic detection equipment degrades by the bubbles around. However, the research on reducing bubble generation in the moonpool and sweepdown effects is rare. So in present paper the reduction effects of damping devices such as the flange and choke deck on the bubble generation in the moonpool are investigated experimentally. Then, in order to reduce the sweepdown effects of bubbles on the ship bottom, three other damping devices which are double flaps, diversion channel and wedge are investigated. It can be seen that through reducing the area of bubble leakage in the moonpool the distribution position of bubbles can be effectively restricted and the width and thickness of the bubbles reduce.

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“…e adverse effects were the increase in resistance, increase in structural motion, green water, and so on [8][9][10][11][12][13]. To reduce the adverse effects, the damping devices were researched [14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Research on Oscillating Characteristics of the Shear Layer on the Ship Bottom with a Moonpool under the Action of the Current and Wave

Huang

Yao

Shi

et al. 2021

Mathematical Problems in Engineering

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For some research vessels, a sonar is installed in the moonpool, and some acoustic detection equipment are installed on the ship bottom behind the moonpool, which helps to avoid the impact of the high-speed flow. The moonpool causes the ship bottom discontinued, forming a particular shear layer oscillation. The shear layer oscillation affects the bubble generation and motion in and behind the moonpool. The sonar and acoustic equipment will malfunction when surrounded by many bubbles. However, there is almost no research on the shear layer oscillation near the moonpool. So, in this paper, by measuring the pressure near the moonpool and monitoring the fluid motion in the moonpool and bubbles’ distribution along the ship bottom, the shear layer oscillation near the moonpool is studied experimentally under the action of the incident current and wave. Furthermore, the effects of the sonar and the moonpool shape are investigated. It can be seen that the shear layer oscillation excites the fluid motion in the moonpool. The sonar forms a complicated boundary in the moonpool, resulting in the increase in the frequency of the shear layer oscillation. The shear layer propagates along the ship bottom in the form of the ship bottom wave. Clarifying the oscillating characteristics of the shear layer along the ship bottom with a moonpool is conducive to the design of moonpools in the research ships, and the detection instruments are arranged in the right place along the ship bottom, so as to make sure the detection instruments work properly and detect the marine environment more accurately.

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Monocolumn behavior in waves: Experimental analysis

Cited by 40 publications

References 3 publications

The Dynamic Effects of Water Column Inside the Turret of an FPSO

The Dynamic Effects of Water Column Inside the Turret of an FPSO

Reducing bubble generation and sweepdown effect on a research vessel with a moonpool

Research on Oscillating Characteristics of the Shear Layer on the Ship Bottom with a Moonpool under the Action of the Current and Wave

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