URANS simulations for a flooded ship in calm water and regular beam waves

Sadat-Hosseini, H.,Kim, D.H.,Carrica, P.M.,Rhee, S.H.,Stern, F. Pergamon Press 2016 Ocean engineering Vol.120 No.-

CFD simulations are conducted for zero-speed damaged passenger ship SSRC in calm water and waves with 6DOF motions including flooding procedure in calm water, roll decay in calm water and motions in regular beam waves for various wavelengths. The simulations model the 6DOF soft spring experimental mount, the one- and two-room flooding compartment configurations, including both intact and damaged conditions. For flooding and roll decay, simulations show ability to predict the trend of increases in roll period and damping due to flooding, as reported in ITTC. The damping magnitudes were often under-predicted with large errors while the roll period and compartment water height were well predicted. Two-room compartment simulation showed three times larger damping than one-room compartment cases whereas the roll period was similar for both conditions. For wave cases, all motions show primarily 1st order responses, except for parametric roll condition which shows large ½ harmonic responses for the intact ship. The 2nd order responses are small for both damaged and intact ship. The larger roll period and damping for the damaged ship shift the peak of responses to smaller wave frequency and reduce the amplitude of responses. The average error is often large for 1st order intact ship pitch and damaged ship surge and pitch. The errors are larger for most ½ and 2nd order responses. Large errors could be partially due to the complex mounting system in the experiment. Overall, current CFD results show better predictions than those reported for potential flow solvers even though the computational cost is larger.

국부적인 선체 손상 시 유입수의 동적 특성에 관한 연구

김윤호(Yoon-Ho Kim),이규정(Kyu-Jung Lee),조석규(Seok-Kyu Cho),홍사영(Sa-Young Hong) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

When a ship is damaged and flooded, the motion of the damaged-ship is significantly influenced by the flooding water dynamics. To evaluate the dynamic characteristics of the damaged ship, it is necessary to analyze the forces and the moments applied on the ship walls. In this study, the model experiments were conducted to simulate the simple damaged part of ITTC RORO passenger and the numerical analysis by FLOW3D was carried out with the three-dimensional models. The internal flow was demonstrated and the forces and the moments applied on the ship wall was measured and calculated. The results of computational simulations approximately agree with those of the model experiments. It is shown that three dimensional numerical simulation can be applied to flooding water dynamics.

선내탑재 의사결정지원 시스템을 위한 발라스트 최적화 알고리즘에 관한 연구

신성철(Sung-Chul Shin) 한국항해항만학회 2005 한국항해항만학회지 Vol.29 No.10

선박 침수 사고의 경우, 선박의 운용 책임자가 취할 수 있는 대응방안이 한정되어 있어 정확한고 신속한 의사결정을 위해서는 기존의 안전관련 시스템을 활용한 효율적인 의사결정 지원 시스템이 필요하다. 수밀 및 준수밀 문, 격벽 밸브, 배수 펌프 등과 같이 침수 사고 시작동하는 대부분의 시스템들은 침수가 선박 전체로 전파되는 것을 막도록 충분한 구획분할 정도를 확보하는데 목적이 있다. 침수 시나리오가 파국적이지 않다고 가정하더라도 발라스트 탱크의 사용은 침수 전파 방지와 선박 안정성을 향상하기 위한 매우 효과적인 방안이 될 수 있다. 본 논문에서는 침수 손상 시 최적의 대응방안을 위해 채워져야 하는 발라스트 탱크들을 선정하고, 각 발라스트 탱크의 수위를 결정하는 최적화 알고리즘을 기술한다. Because there are only a limited number of means of action that are available for the master to pursue in the event of flooding, onboard decision support system has been required. The majority of systems activated during a flooding emergency (such as watertight and semi-watertight doors, bulkhead valves, dewatering pumps etc.) almost exclusively aim to restore a sufficiently high level of subdivision to prevent flooding from spreading through the ship. Even though assuming the flooding scenario is not catastrophic, the use of ballast tanks can be an additional and very effective tool to ensure both prevention of flooding spreading and also improve ship stability. This paper describes an optimization algorithm devised to choose the set of ballast tanks that should be filled in order to achieve an optimal response to a flooding accident.

선박 디젤엔진용 로터 캡 디스크 스프링의 피로해석 연구

양영준 한국기계기술학회 2021 한국기계기술학회지 Vol.23 No.4

Diesel engine is used many industrial fields such as ship, power plant and big-sized vehicles and so on. Roto cap is one of the parts of system of intake and exhaust valve. Roto cap consists of body, disc spring, spring & steel ball, retainer and stop ring. Disc spring is known as taking cyclic load and cyclic load leads to fatigue damage. This study aims to investigate the stability of disc spring due to fatigue damage. As the results, the fatigue life of disc spring according to cylic load could be predicted using fatigue analysis. Consequently, disc spring showed the stability of about 1.7~2 times for criterion load of 1370N.

Study of damage safety assessment for a ship carrying radioactive waste

Lee, Dong-Kon,Choi, Jin,Park, Beom-Jin,Kang, Hee-Jin,Lim, Suk-Nam The Society of Naval Architects of Korea 2012 International Journal of Naval Architecture and Oc Vol.4 No.2

Ship damage caused by maritime casualties leads to marine pollution and loss of life and property. To prevent serious damage from maritime casualties, several types of safety regulations are applied in ship design. Damage stability regulation is one of the most important safety issues. Designs of ships for long international voyages must comply with these regulations. Current regulations, however, do not consider the characteristics of the operating route of each ship and reflect only ship size and type of cargo. In this paper, a damage safety assessment was undertaken for a ship carrying radioactive waste in actual wave conditions. Damage cases for safety assessment were constructed on the basis of safety regulations and related research results. Hull form, internal arrangement, loading condition and damage condition were modeled for damage safety simulation. The safety simulation was performed and analyzed for 10 damage cases with various wave heights, frequency and angle of attack on an operating route. Based on evaluation results, a design alternative was generated, and it was also simulated. These results confirmed that damage safety analysis is highly important in the design stage in consideration of the operating route characteristics by simulation. Thus a ship designer can improve safety from damage in this manner.

Study of damage safety assessment for a ship carrying radioactive waste

Dongkon Lee,Jin Choi,Beom Jin Park,Hee Jin Kang,Suknam Lim 대한조선학회 2012 International Journal of Naval Architecture and Oc Vol.4 No.2

Ship damage caused by maritime casualties leads to marine pollution and loss of life and property. To prevent serious damage from maritime casualties, several types of safety regulations are applied in ship design. Damage stability regulation is one of the most important safety issues. Designs of ships for long international voyages must comply with these regulations. Current regulations, however, do not consider the characteristics of the operating route of each ship and reflect only ship size and type of cargo. In this paper, a damage safety assessment was undertaken for a ship carrying radioactive waste in actual wave conditions. Damage cases for safety assessment were constructed on the basis of safety regulations and related research results. Hull form, internal arrangement, loading condition and damage condition were modeled for damage safety simulation. The safety simulation was performed and analyzed for 10 damage cases with various wave heights, frequency and angle of attack on an operating route. Based on evaluation results, a design alternative was generated, and it was also simulated. These results confirmed that damage safety analysis is highly important in the design stage in consideration of the operating route characteristics by simulation. Thus a ship designer can improve safety from damage in this manner.

Ship Stability Calculation for Cause Analysis of No. 501 Oryong Sinking Accident

Sang-Gab Lee,Jae-Seok Lee,Jee-Hun Kim 한국항해항만학회 2018 한국항해항만학회 학술대회논문집 Vol.2018 No.추계

Deep-sea fishing vessel No. 501 Oryong was fully flooded through the openings and was sunk down to the bottom of sea due to the very rough sea weather on the way of evasion after fishing operation in the Bearing Sea with many crews dead and/or missed. In this study, calculation of ship stability was carried out using KST-SHIP(ship calculation system of KST), considering the effect of flow fluid and fish catch arrangement according to the progress of its sinking accident, and damage stability was analyzed. For this study, intact stability calculation of its accident ship under the full load departure condition and its calculation result were verified by comparing with each other, and intact stability according to displacement from the departure of accident ship just before the accident was calculated and analyzed. Damage stability was calculated according to the progress during sinking accident and also analyzed.

Parameter space exploration for the probabilistic damage stability method for dry cargo ships

Milatz Bas,de Winter Roy,van de Ridder Jelle D.J.,van Engeland Martijn,Mauro Francesco,Kana Austin A. 대한조선학회 2023 International Journal of Naval Architecture and Oc Vol.15 No.-

The prediction of the statutory attained subdivision index is a challenging issue for the initial design of ships due to the design freedom offered by a probabilistic damage stability assessment. To this end, optimisation techniques integrated with a parametric model of the internal layout may generate a preliminary subdivision design, fulfilling damage stability regulations and cargo volume requirements. The present study explores using a multiobjective constrained optimisation algorithm coupled with a parametric model of a single hold cargo vessel, first investigating two design goal alternatives and secondly performing a global sensitivity analysis on the design variables for the most promising solution. The adoption, in parallel, of state-of-the-art practices shows the validity of the obtained solutions and the time benefits for designers. Nonetheless, the non-linear nature of probabilistic damage stability does not allow for clearly identifying the most impactful parameters on the attained survivability index.

Preliminary tests of a damaged ship for CFD validation

Lee, Sung-Kyun,You, Ji-Myoung,Lee, Hyun-Ho,Lim, Tae-Gu,Rhee, Shin-Hyung,Rhee, Key-Pyo The Society of Naval Architects of Korea 2012 International Journal of Naval Architecture and Oc Vol.4 No.2

One of the most critical issues in naval architecture these days is the operational safety. Among many factors to be considered for higher safety level requirements, the hull stability in intact and damaged conditions is the first to ensure for both commercial and military vessels. Unlike the intact stability cases, the assessment of the damaged ship stability is very complicated physical phenomena. Therefore it is widely acknowledged that computational fluid dynamics (CFD) methods are one of most feasible approaches. In order to develop better CFD methods for damaged ship stability assessment, it is essential to perform well-designed model tests and to build a database for CFD validation. In the present study, free roll decay tests in calm water with both intact and damaged ships were performed and six degree-of-freedom (6DOF) motion responses of intact ship in regular waves were measured. Through the free roll decay tests, the effects of the flooding water on the roll decay motion of a ship were investigated. Through the model tests in regular waves, the database that provides 6DOF motion responses of intact ship was established.

Preliminary tests of a damaged ship for CFD validation

이성균,Ji-Myoung You,Hyun-Ho Lee,Taegu Lim,이신형,이기표 대한조선학회 2012 International Journal of Naval Architecture and Oc Vol.4 No.2

One of the most critical issues in naval architecture these days is the operational safety. Among many factors to be considered for higher safety level requirements, the hull stability in intact and damaged conditions is the first to ensure for both commercial and military vessels. Unlike the intact stability cases, the assessment of the damaged ship stability is very complicated physical phenomena. Therefore it is widely acknowledged that computational fluid dynamics (CFD) methods are one of most feasible approaches. In order to develop better CFD methods for damaged ship stability assessment, it is essential to perform well-designed model tests and to build a database for CFD validation. In the present study, free roll decay tests in calm water with both intact and damaged ships were performed and six degree-of-freedom (6DOF) motion responses of intact ship in regular waves were measured. Through the free roll decay tests, the effects of the flooding water on the roll decay motion of a ship were investigated. Through the model tests in regular waves, the database that provides 6DOF motion responses of intact ship was established.