• International Journal of Ocean System Engineering
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• 제3권4호
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• pp.169-174
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• 2013

The computational fluid dynamics software FLUENT is used to calculate and compare the hydrodynamic performance of the propeller-rudder system of a 42-m trawler, which is installed with a ducted propeller. The effects of rudder on the hydrodynamic performance of the ducted propeller and the wake flow behind the propeller are firstly investigated. In addition, the different rudder angles are also considered to further study the performance of this system.

• Journal of Ship and Ocean Technology
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• 제12권4호
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• pp.20-31
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• 2008

Development of rudder gap flow blocking device for lift augmentation and cavitation suppression is presented. In order to verify the performance of this device, cavitation visualization and surface pressure measurements were carried out in a cavitation tunnel. Numerical simulations were conducted using a computational fluid dynamics code for more rigorous verification. The new rudder system is equipped with cam devices, which effectively close the gap between the horn/pintle and movable wing parts. The experimental and computational results show that the proposed rudder system is superior to the conventional rudder systems in terms of the lift augmentation and cavitation suppression.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권2호
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• pp.177-184
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• 2017

The Coanda effect is the phenomenon of a fluid jet to stay attached to a curved surface; when a jet stream is applied tangentially to a convex surface, lift force is generated by increase in the circulation. The Coanda effect has great potential to be applied practically applied to marine hydrodynamics where various lifting surfaces are being widely used to control the behavior of ships and offshore structures. In the present study, Numerical simulations and corresponding experiments were performed to ascertain the applicability of the Coanda effect to a horn-type rudder. It was found that the Coanda jet increases the lift coefficient of the rudder by as much as 52% at a jet momentum coefficient of 0.1 and rudder angle of $10^{\circ}$.

• 한국해양공학회지
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• 제27권6호
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• pp.112-118
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• 2013

This paper reports the results of a comparative study on rudder performance between the steel rudders that have been used in coastal angling fishing boats in the 20-GT class and the newly developed FRP composite material rudders. In order to compare the rudder performances of these two types, a sea trial test was carried out to investigate the speed performance, fuel consumption, and ship's turning ability. The results showed that the sea trial performance of the FRP composite rudder was better than that of the steel rudder type in terms of the sea speed, fuel consumption rate, and turning ability.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2010년도 춘계학술대회
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• pp.387-388
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• 2010

선박의 조종성능 향상을 위해 적용되고 있는 쌍동타의 유체력 평가를 위해 $Re=1.5\times10^4$에서 쌍동타의 상 하부 리더 간격을 변화시켜 주위 유동을 계측하였다. 영각에 따른 쌍동타 주위에서 생성되는 와의 생성과 소멸 메커니즘을 이해하기 위해 속도 및 에너지 분포를 2-프레임 그레이레벨 상호상관 PIV기법을 이용하여 비교 분석하였다. 쌍동타의 상 하부 간극의 영향에 따른 측압력은 0.75L에서 향상되었다.

• 대한조선학회논문집
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• 제43권5호
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• pp.568-577
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• 2006

With the increase of ship size and speed, the loading on the propeller is increasing, which in turn increases the rotational speed in the propeller slipstream. The rudder placed in the propeller slip stream is therefore subject to severe cavitation with the increased angle of attack due to the increased rotational induction speed of the propeller. In the present paper the surface panel method, which has been proved useful in predicting the sheet cavitation on the propeller blade, is applied to solve the cavity boundary value problem on the rudder. The problem is then solved numerically by discretizing the rudder and cavity surface elements of the quadrilateral panels with constant strengths of sources and dipoles. The strengths of the singularities are determined satisfying the boundary conditions on the rudder and cavity surfaces. The extent of the cavity, which is unknown a priori, is determined by iterative procedure. Series of numerical experiments are performed increasing the degree of complexity of the rudder geometry and oncoming flows from the simple hydrofoil case to the real rudder in the circumferentially averaged propeller slipstream. Numerical results are presented with experimental results.

• 한국항해항만학회지
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• 제29권10호
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• pp.839-845
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• 2005

조타에 의해 불규칙파 중 선박의 선수동요 및 횡요를 제어하는 횡요 감소시스템에 관한 연구를 수행하였다. 횡요를 포함한 선박 운동 시뮬레이션을 위해 4-자유도 조종 운동방정식을 사용하였고, 선체에 가해지는 외력으로서 파강제력이 고려되었다. 파강제력은 3차원 특이점 분포법에서 얻어진 주파수 전달함수로부터 시간영역해석법을 적용하였다. 선수동요와 횡요를 제어하는 PD 제어기를 각각 구성하고, 이를 선형 결합하여 횡요 감소 조타 제어기를 구성하였다. 조타 속도 및 타의 종류를 변화시켜 선수동요 및 횡요의 제어효율을 검토하였다.

• 수산해양기술연구
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• 제56권2호
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• pp.172-182
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• 2020

In order to offer specific information needed to assist in operation of a ship with same type rudder through evaluating the maneuverability of training ship A-Ra with flapped rudder, sea trials based full scale for turning test, zig-zag test with rudder angle 10° and 20°, and spiral test at service condition were carried out on starboard and port sides around Jeju Island according to the standards of maneuverability of IMO. As a result, the angular velocity of port turn was higher than that of starboard turn. Therefore, the size of turning circle was longer on the starboard side. In addition, variation of the transfer due to various factors was more stable than those of the others. In the Z-test results, the mean of 1st and 2nd overshoot angles were 9.8°, 6.3° and 15.3°, 9.2° respectively when the port and starboard was 10°; the 1st overshoot angle were 18°, 13.7° when using 20°. Her maneuverability index T' and K' can be easily determined by using a computer with the data obtained from Z-test where K' and T' are dimensionless constants representing turning ability and responsiveness to the helm, respectively. In the Z-test under flap rudder angle 10°, the obtained K' value covered the range of 2.37-2.87 and T' was 1.74-3.45. Under the flap rudder angle 20°, K' and T' value showed 1.43-1.63, 1.0-1.73, respectively. In the spiral test, the loop width was unstable at +0.3° and -0.5°-0.9° around the midship of flap rudder. As a result, course stability was comparatively good. From the sea trial results, training ship ARA met the present criterion in the standards of maneuverability of IMO.

• 대한조선학회논문집
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• 제48권2호
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• pp.128-133
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• 2011

In the present study, the flow fields in between the propeller and the semi-spade rudder are investigated by using PIV technique to find out the influences of both simulated hull wake and propeller wake on the incident flow to the rudder. The velocity fields are measured at the propeller rotation angle of $180^{\circ}$ and the rudder deflection angles of $0^{\circ}$. Flow fields measured at each rudder deflection angle are analyzed in terms of angle-of-attack against the rudder leading edge. The hull wake increases the angle-of-attack more than that in the uniform inflow condition, forming the angle-of-attack of about $20^{\circ}$ at 0.7R(R=propeller radius) position. The distribution of the angle-of-attack is strongly affected by the stagnation point around the leading edge and camber effect of the rudder. These effects provide asymmetric distribution of angle-of-attack with respect to the leading edge of the rudder.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 추계학술대회 논문집
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• pp.55-61
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• 2005

조타에 의해 불규칙파$\cdot$중 선박의 선수동요 및 횡요를 제어하는 횡요 감소시스템에 관한 연구를 수행하였다. 횡요를 포함한 선박 운동 시뮬레이션을 위해 4-자유도 조종 운동방정식을 사용하였고, 선체에 가해지는 외력으로서 파강제력이 고려되었다. 파강제력은 3차원 특이점 분포법에서 얻어진 주파수 전달함수로부터 시간영역해석법을 적용하였다. 선수동요와 횡요를 제어하는 PD 제어기를 각각 구성하고, 이를 선형 결합하여 횡요 감소 조타 제어기를 구성하였다. 조타 속도 및 타의 종류를 변화시켜 선수동요 및 횡요의 제어효율을 검토하였다.