• Title/Summary/Keyword: Moon pool

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Flow Analysis of Two-Dimensional Floating Body with Moon Pool Using a Numerical Wave Tank (수치 파동 수조를 이용한 부유체의 문풀 (Moon Pool) 유동해석)

  • Koo, Weon-Cheol;Lee, Kyoung-Rok
    • Journal of the Society of Naval Architects of Korea
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    • v.48 no.2
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    • pp.107-112
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    • 2011
  • The aim of this study is to analyze the hydrodynamic properties of a 2D floating body with moon pool using a 2D fully nonlinear Numerical Wave Tank(NWT). This NWT was developed based on the Boundary Element Method(BEM) with potential theory and fully nonlinear free surface boundary conditions. Free surface elevations in the moon pool were calculated in the time domain for various frequencies of forced body motions. The added-mass and damping coefficients of the heaving body were also obtained. The present numerical results were compared with the analytic and experimental results and their accuracy was verified.

Evaluation of Structural Integrity of the ISO-based Moon Pool Type Diver Boats (ISO 기반 Moon Pool형 다이버 보트 구조 건전성 평가)

  • Kang, Byoung-mo;Oh, Woo-jun;Na, Hyun-ho;Choi, Ju-seok
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.5
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    • pp.597-603
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    • 2018
  • This Study investigates the Structural Integrity of Boats for Divers, given increased demands for Underwater and Recreational use. We conducted research on a Small Catamaran with a Moon Pool in the center of the Hull, using the Finite Element Method to calculate allowable stress based on the ISO Rule. We computed the coefficients defined in ISO 12215-5 and TC118.1225-7, and determined the suitability of using the ISO Standard and Allowable Stress Design method (ASD) by applying Longitudinal Bending Moment, Torsional moment, and Bottom Slamming Load. We also applied the Ultimate Strength Design Method (LFRD) using Finite Element Analysis (FEA). As a Result of this Research, it was found that ships with a Moon Pool do have Structural Integrity according to their Design in accordance with ISO and KR Regulations.

Welding Deformation and Its Correction of Cylindrical Moon Pool Structure (원통형 문풀 구조물의 탑재 시 변형과 수정)

  • Seong, Woo-Jae;Chun, Kwang-San
    • Journal of the Society of Naval Architects of Korea
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    • v.56 no.5
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    • pp.389-395
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    • 2019
  • Turret mooring type Floating Production Storage and Offloading (FPSO) is designed to rotate the hull around a turret system. The system is mounted inside a cylindrical moon-pool structure of the ship hull structure. The upper part of the moon-pool structure called Bogie Support Structure (BSS) is supported on ring type rail structure (bogie), so high roundness is required at the top of the structure. In this study, the deformation measured during BSS installation was compared with the predicted values through the thermal elasto-plastic analysis, and the causes of deformation were analyzed. Deformation behavior of cylindrical structure with a very large diameter compared to the thickness was investigated. In addition, a proper welding sequence and correction method for the deformed structure were proposed. This study can be an example of the solution to the tolerance problem of large cylindrical structures.

CFD Analysis of Two-Dimensional Floating Body with Moon Pool under Forced Heave Motion (문풀을 가지는 2차원 부유체의 강제 상하동요에 대한 CFD 해석)

  • Heo, Jae-Kyung;Park, Jong-Chun;Kim, Moo-Hyun
    • Journal of Ocean Engineering and Technology
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    • v.25 no.2
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    • pp.36-46
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    • 2011
  • A two-dimensional floating body with a moon pool under forced heave motion, including a piston mode, is numerically simulated. A dynamic CFD simulation is carried out to thoroughly investigate the flow field around a two-dimensional moon pool over various heaving frequencies. The numerical results are compared with experimental results and a linear potential program by Faltinsen et al. (2007). The effects of vortex shedding and viscosity are investigated by changing the corner shapes of the floating body and solving the Euler equation, respectively. The flow fields, including the velocity, vorticity, and pressure fields, are discussed to understand and determine the mechanisms of wave elevation, damping, and sway force.

A Study on the Weld-Induced Deformation and Residual Stress Analysis at FPSO Moon Pool Structure (FPSO Moon Pool 구조의 용접변형과 잔류응력에 관한 연구)

  • Han, Sung-Woo;Lee, Joo-Sung;Kim, Sang-Il
    • Journal of the Society of Naval Architects of Korea
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    • v.48 no.5
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    • pp.473-478
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    • 2011
  • Welding process generates distortion and residual stress in the weldment due to rapid heating and cooling. Welding distortion and residual stress in the welded structure result in many troubles such as dimensional inaccuracies in assembling and safety problem during service. The accurate prediction of welding residual stress is thus very important to improve the quality of weldment and find the way to reduce itself. This paper presents the simulation of welding-induced residual stress analysis to examine the cause of cracking in the SUS-overlay welding specimen at FPSO Moon Pool structure.

A Study on the Weld-induced Residual Stress Analysis at FPSO Moon Pool Structure (FPSO Moon Pool 구조에서 발생되는 용접 잔류응력에 관한 연구)

  • Lee, Joo-Sung;Han, Sung-Woo;Lee, Sang-Hoon;Kim, Sang-Il
    • Journal of Welding and Joining
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    • v.29 no.3
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    • pp.70-75
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    • 2011
  • Welding process generates distortion and residual stress in the weldment due to rapid heating and cooling. Welding distortion and residual stress in the welded structure result in many troubles such as dimensional inaccuracies in assembling and safety problem during service. The accurate prediction of welding residual stress is thus very important to improve the quality of weldment and find the way to reduce itself. This paper presents the simulation of welding-induced residual stress analysis to examine the cause of cracking in the SUS-overlay welding specimen at FPSO Moon Pool structure.

A Study of the Characteristics of Unsteady Laminar Jet Submerged into a Suppression Pool (응축 풀 내의 비정상 층류 제트의 유동 특성에 관한 연구)

  • Choi, Yong Moon;Kim, Chong Bo
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.17 no.4
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    • pp.499-507
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    • 1988
  • The pressure suppression pool of BWR(Boiling Water Reactor) is subjected to hydrodynamic impact in the event of a LOCA(Loss of Coolant Accident). The pressure increase in the reactor dry cell would force the existing water of a vent pipe into the suppression pool. When the water is ejected through the pipe opening into the suppression pool, an abrupt downward force is transmitted to the suppression pool floor. Consequently, many structures installed within the pool must be able to withstand these forces. In order to determine the optimum safe locations of the pool structures, numerical analysis have been carried out to investigate the hydrodynamic behavior of the water jet. In the present analysis, a two-dimensional numerical model is utilized to solve transient flow equations.

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Variability of Surface Chlorophyll Concentration in the Northwest Pacific Ocean (북서태평양의 표층엽록소 변동성)

  • Park, Ji-Soo;Suk, Moon-Sik;Yoon, Suk;Yoo, Sin-Jae
    • Ocean and Polar Research
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    • v.30 no.3
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    • pp.277-287
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    • 2008
  • We collected information on seasonal and interannual variability of surface chlorophyll a concentration between 1997-2007 from the Northwest Pacific Ocean. Satellite data were used to acquire chlorophyll a and sea surface temperature from six regions: East Sea/Ulleung Basin, East China Sea, Philippin Sea, Warm Pool region, Warm Pool North region, and Warm Pool East region. Mixed layer depth (MLD) was calculated from temperature profiles of ARGO floats data in four of the six regions during 2002-2007. In the East Sea/Ulleung Basin, seasonal variability of chlorophyll a concentration was attributed to seasonal change of MLD, while there was no significant relationship between chlorophyll a concentration and MLD in the Warm Pool region. Interannual anomaly in sea surface temperature were similar among the East Sea, East China Sea, Philippin Sea, and Warm Pool North region. The anomaly pattern was reversed in the Warm Pool East region. However, the anomaly pattern in the Warm Pool region was intermediate of the two patterns. In relation to chlorophyll a, there was a reversed interannual anomaly pattern between Warm Pool North and Warm Pool East, while the anomaly pattern in the Warm Pool region was similar to that of Warm Pool North except for the El $Ni\tilde{n}o$ years (1997/1998, 2002/2003, 2006/2007). However, there was no distinct relationship among other seas. Interestingly, in the Warm Pool and Warm Pool East regions, sea surface temperature showed a pronounced inverse pattern with chlorophyll a. This indicates a strong interrelationship among sea surface temperature-MLD-chlorophyll a in the regions. In the Warm Pool and Warm Pool East, zonal distribution of chlorophyll a concentration within the past 10 years has shown a good relationship with sea surface temperature which reflects ENSO variability.