• Ocean Systems Engineering
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• 제10권1호
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• pp.87-110
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• 2020

Catamaran has recently been a choice to support a typical vertical axis turbine in floating tidal current energy conversion system. However, motion responses associated with the catamaran can reduce the turbines efficiency. The possibility to overcome this problem isto change the catamaran parameter by varying and simulating the demi-hull separations to have lower motion responses. This simulation was undertaken by Computational Fluid Dynamic (CFD) using potential flow analysis. Cases of demi-hull separation were considered, with ratios of demi-hull separation (S) to the breadth of demi-hull (B), ^S/_B of 3.45, 4.95, 6.45, 7.2 and 7.95. In order to compare to the previous works in the literature, the regular wave was set with wave height of 0.8 m. Furthermore, the analysis was carried out by irregular waves with significant wave height, H_s, of about 0.09 to 1.5 m and the wave period, T, of about 1.5 to 6 s or corresponding to the wave frequency, ω, of about 1.1 to 4.2 rad/s. The wave spectrum was derived from the equation of the International Towing Tank Conference (ITTC). For the case of turbines-loaded catamaran under consideration, the new finding is that the least significant amplitude response can be satisfied at the ratio ^S/_B of 7.2. This study indicates that selecting a right choice of demi-hull separation ratio could contribute in reducing motion responses of the tidal current turbines-loaded catamaran.

• 로봇학회논문지
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• 제11권4호
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• pp.217-225
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• 2016

Dynamic Positioning (DP) is used to automatically maintain the position and heading of a floating structure subjected to environmental disturbances. A DP control system is composed of a motion controller to compute the desired force and moment and a thrust allocator to distribute the computed force and moment to multiple thrusters considering mechanical and operational constraints. Among various thruster configurations, azimuth thrusters or propeller/rudder pairs tend to make the allocation problem difficult to solve, because these types of propulsion systems include nonlinear constraints. In this paper, a dynamic positioning strategy for a twin-thruster ship that is propelled by two azimuthing thrusters is addressed, and a thrust allocation method which does not require a numerical optimization solver is proposed. The applicability of the proposed method is demonstrated with an experiment using an autonomous boat.

• 대한조선학회논문집
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• 제45권4호
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• pp.361-369
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• 2008

The optimized distance between skegs and angle of the skeg for a standard twin-skeg type LNG carrier were presented using the CFD and model tests. The evaluation method of self-propulsion performance was derived based on the results of CFD and confirmed the validity through model tests. The analyses to assess self-propulsion performance using CFD were shown by flow line patterns on the skeg surface, nominal wake distribution in the propeller plane and the evaluation for flow balance around stern skegs. The optimized ship that was applied to the optimized two design parameters in stern skeg arrangement for target ship was derived in this work. Finally speed performance of mother ship which is existing ship and optimized ship were compared through CFD and model tests. And the usefulness about the evaluation method of self-propulsion performance was reconfirmed.

• 대한조선학회논문집
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• 제29권3호
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• pp.102-116
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• 1992

하나 또는 두개의 지주를 가지는 소수선면 쌍동선의 유체동역학적 특성에 대한 비교 연구결과를 다루었다. 두 모형선으로 정수중에서의 저항, 파랑중에서 정지 및 속도를 가질 때의 6자유도 운동응답, 그리고 파랑하중 등을 수조 실험실에서 측정하였으며 수치해석결과들과 자세하게 비교하였다. 본 연구 결과에 의거하여 두 SWATH 모델들의 장단점을 열거하였으며 이는 SWATH선의 설계 고려에 유익하게 쓰여질 수 있다고 생각된다.

• 해양환경안전학회지
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• 제24권1호
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• pp.126-132
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• 2018

본 연구에서는 쌍동형 카페리에 다수 존재하는 유공판의 좌굴강도 설계 수행 결과 및 개선사항을 논의하고 있다. 카페리와 같이 길이가 50미터 이상이고, 길이/폭의 비가 12보다 큰 중/소형 고속선박은 상대적으로 두께가 얇고 연강을 사용함으로서 좌굴강도가 취약해질 가능성이 농후하다. 특히, 작업자의 접근 및 통로로 활용되는 유공판에서 좌굴강도가 취약해질 가능성이 있다. 안전한 구조설계를 위해서는 유공주위의 면내 하중 재 분포에 의한 좌굴강도 및 최종강도에 대한 명확한 검토가 필요하다. 본 연구에서는 유공판의 좌굴 및 최종강도 특성에 영향을 미치는 매개변수의 영향을 종합적으로 고려하기 위하여 유한요소해석 프로그램인 ANSYS를 활용한 비선형시리즈 해석을 수행하였으며, 주요 변수(종횡비, 유공비, 유공형상)들에 대한 영향을 검토하였다. 이 결과를 바탕으로 하여, 유공판의 좌굴강도를 결정짓는 가장 큰 인자는 유공비였으며, 종횡비와 유공의 형상은 그 영향이 미비하였다.

• 대한조선학회지
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• 제24권4호
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• pp.71-83
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• 1987

There is at present a growing interest in the use of SWATH(Small Waterplane Area Twin Hull )ship for a variety of purposes due to their good seakeeping characteristics, small speed reduction in wave, and large deck area. Highly sophisticated design technology is requested to develop the SWATH ship. This paper describes the design technology for high speed coastal passenger SWATH ship which includes feasibility study, general arrangement and hull form design, resistance and propulsion test, motion test in regular waves, control fin design, and structural design.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.518-530
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• 2020

The present study concerns the stern slamming load of container carriers, with stern bulb arrangement variation. First, a series of wedge drop tests were conducted using simple wedge models with fixed deadrise angles, and tests with the cross-section models of practical container carrier sterns were followed. The deadrise angle of the simple wedge ranged from 0° to 10°. The pressure measurement results of the simple wedge drop tests were distributed between empirical formula and analytic solution, so the experimental setup was validated. In the cases of practical hull cross-sections, the water entry of the bulb prior to that of the transom resulted in characteristic water film generation and delayed pressure peak appearance. The trapped air between the bulbs damped the pressure in the twin skeg hull case, reducing the pressure peak and causing the pressure oscillation during water entry.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 추계학술대회 논문집
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• pp.220-225
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• 2003

• 한국항해학회지
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• 제12권3호
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• pp.39-53
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• 1988

반 잠수식 저 수선면적 쌍동선(Small WAterplane Area Twin Hull) 의 총 저항 추정을 위한 새로운 전산 program 개발에 대해서 개략적으로 설명하였다. SWATH ship의 총저항을 조파 저항, 표면 마찰 저항, Fin 저항 및 부가 저항의 합으로 계산하였다. 개발된 program의 정확성을 확인하기 위해서 수치 해석결과를 세 가지 SWATH 모델들의 실험치와 비교하였다.

• 해양환경안전학회지
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• 제24권7호
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• pp.923-929
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• 2018

본 연구에서는 쌍동선체의 선수형상에 대해 일반적으로 적용되고 있는 재래식과 선수 돌출의 반전형 선수 형상에 대한 저항성능 및 항주자세를 수치해석을 통해 분석하고, 반전형 선수형상에 대해서는 모형시험을 통하여 수치해석과 비교분석하였다. 반전형 선수형상은 재래식 선수형상보다 선수 발산파 파정의 생성위치를 선미방향으로 이동시켜 개선된 조파현상을 보였으며, 저항 및 안정된 항주자세 결정에 효과적이며 선체 저항이 약 2.95 % 개선되었다. 반전형 선수형상에 대한 수치해석 및 모형시험 비교분석 자료는 향후 선형설계 활용에 유용할 것으로 판단된다.