• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.813-824
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• 2004

The paper studies the effect of neighboring blade rows on flutter characteristics of cascading blades. For this purpose the computation program to calculate the unsteady blade loading based on the un-steady lifting surface theory for contra-rotating annular cascades was formulated and coded. Then a computation program to solve the coupled bending-torsion flutter equation for the contra-rotating annular cascades was also developed. Some results of the flutter analysis are presented. The presence of the neighboring blade row gives rise to significant change in the critical flutter condition when the main acoustic duct mode is of cut-on state.

• 대한조선학회논문집
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• 제41권3호
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• pp.13-21
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• 2004

This paper deals with a theoretical and experimental method for the design of a biased asymmetric pre-swirl stator propulsion system which is an energy saving device by recovering a propeller rotational energy. In the case of slow-speed ships, the upward flow is generated along the afterbody hull form at the propeller plane. The generated upward flow cancels the rotating flow of the propeller at the starboard part while it increases at port part. The present biased asymmetric pre-swirl stator propulsion system consists of three blades at the port and one blade at the starboard which can recover the biased rotating flow effectively. This paper provides the design concept which gives more simple and a high degree of efficiency and the experimental results for the compound propulsion system.

• 한국해양공학회지
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• 제33권5호
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• pp.377-386
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• 2019

Flexible composite propellers have a relatively large deformation under heavy loading conditions. Thus, it is necessary to accurately predict the deformation of the blade through a fluid-structure interaction analysis. In this work, we present an LST-FEM method to predict the deformation of a flexible composite propeller. Here, we adopt an FEM solver called OOFEM to carry out a structural analysis with an orthotropic linear elastic composite material. In addition, we examine the influence of the lamination direction on the deformation of the flexible composite propeller.

• 대한조선학회지
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• 제27권3호
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• pp.1-10
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• 1990

본 논문에서는 얇은 배 이론, Hess & Smith방법, 유사실적자료 및 모형실험결과를 이용하여 고속콘테이너선의 선형을 개발한 연구결과가 소개도어 있다. 양력면이론에 의해 설계된 고효율 프로펠러는 캐비테이션과 변동압력에서 좋은 성능을 보였으며, 유한요소법에 근거한 최적설계기법으로 선체구조설계와 선체진동해석을 수행하였다. 끝으로, 새로이 개발된 본 고속콘테이너선의 성능을 실선 시운전결과와 비교, 검토하였으며, 이로부터 속력, 진동 및 기타성능에 있어서의 우월성이 확인되었다.

• 대한조선학회논문집
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• 제34권3호
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• pp.9-18
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• 1997

복합추진장치가 포함된 경우와 포함되지 않은 경우의 축대칭 물체 주위 유동특성을 조사하기 위한 실험적 수치적 연구가 수행되었다. 축대칭 물체주위 유동특성 파악을 위해 선박해양공학연구센터의 캐비테이션 터널에서 표면압력분포와 LDV 장치를 이용한 주위유속분포 계측 시험이 우선적으로 이루어졌으며, 비압축성 RANS 방정식을 유한체적법으로 해석하는 수치적 방법이 표준 k-${\varepsilon}$ 난류모형을 이용하여 수행되었다. 선체와 프로펠러 상호작용은 양력면이론에 의하여 계산된 유기속도를 프로펠러 면에 분포하여 경계조건으로 처리하는 방법을 택하였다. 추진장치의 여러 가지 배열변화에 따른 실험적 결과를 기반으로 타당한 수치적 방법이 개발될 수 있다고 생각된다.

• 대한조선학회지
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• 제21권3호
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• pp.27-34
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• 1984

When a ship is travelling in following seas, the encounter frequency is reduced to be very low. In that case broaching phenomenon is most likely to occur, and it may be due to wave exciting forces acting on ships. It is thought that the wave exciting forces acting on ships in following seas almost consist of two components. One is hydrostatic force due to Froude-Krylov hypothesis, and the other is hydrodynamic lift force due to orbital motion of water particles below the wave surface. In the present paper, the emphasis is laid upon wave exciting sway force, yaw moment and roll moment acting on ships in following seas. The authers take the case that the component of ship speed in the direction of wave propagation is equal to the wave celerity, i.e., the encounter frequency is zero. Hydrostatic force components are calculated by line integral method on Lewis form plane, and hydrodynamic lift components are calculated by lifting surface theory. Furthermore captive model tests are carried out in regular following waves generated by means of a wave making board. Through the comparison between calculated and measured values, it is confirmed that the wave exciting forces acting on ships in following seas can be predicted in terms of present method to a certain extent.

• 대한조선학회논문집
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• 제35권1호
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• pp.80-87
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• 1998

선미의 불균일유동장에서 작동하는 박용 프로펠라의 구조적 안전을 평가하는 강도해석 프로그램을 개발하였다. 이 논문은 여러 가지 선종에 대하여 실선자료를 기초로 하여 선속과 스큐각의 관계를 제시하였고, 대형 고속 컨테이너선박의 초기설계시 강도측면에서 스큐각의 최적화를 위하여 여러 가지 스큐각에 대한 프로펠라 강도해석을 수행하였다. 프로펠라 날개는 양력면이론으로부터 계산된 표면압력과 원심력을 받고 있다. 선박의 전진 및 후진시의 프로펠라날개의 구조응답을 구하기 위하여 정적 구조해석을 수행해서 그 결과를 기초로 피로강도를 평가하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.472-478
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• 2004

This paper describes the characteristics of the unsteady pressure on the stator surface induced by rotor viscous wakes. The primary object of this study is to investigate the effects of axial spacing between the rotor and the stator and three-dimensional vane geometries such as stator sweep and stator lean on the unsteady pressure fluctuations on the stator vane. To predict these fluctuations, unsteady three-dimensional Navier-Stokes analyses are performed. Furthermore, a three-dimensional analytical method using unsteady lifting-surface theory is also used to elucidate the mechanism of interaction of passing rotor wakes with downstream stator. Five different fan configurations with three sets of stator geometries, which are three radial stator configurations with different axial spacing, the swept stator and the swept and leaned stator, are used for this study. It is found that, in axial spacing between rotor and stator, the effect of radial phase skew of incoming rotor wake is important for the reduction of the induced unsteady pressure in addition to the rotor wake decay. It is also shown that incorporation of stator sweep and lean is effective to reduce this unsteady pressure.

• 대한조선학회논문집
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• 제36권1호
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• pp.47-52
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• 1999

캐비테이션 터널에서 캐비티가 발생한 프로펠러에 의하여 평판에 작용하는 변동압력이 계측정도를 향상시키고, 프로펠러 회전수 영향을 최소화 하였다. Sydney Express선의 프로펠러 변동압력에 대한 타기관의 계측치 특성과 비교한 결과 당 연구소 계측치는 매우 안정적 경향을 보였다. 그리고 모형선과 실선의 변동압력 계측치 및 평판에 작용하는 변동압력 계측치의 크기와 경향을 비교한다. 평판의 변동압력 계측치로부터 실선 변동압력을 추정코자 양력면 이론에 의한 수치계산에 의해 도출된 강체경계율을 적용하여 타당성을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.604-609
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• 2001

This numerical analysis uses the lifting surface method and frequency-domain panel method based on the linear compressible aerodynamic theory. Increased knowledge of flow conditions within mixed-flow fan should indicates means of improving performance of these turbomachines. Thus, only an approximate solution is obtained whose prime intent is to recognize the most significant characteristics of the "ideal" geometry. For a given set of operating condition, the flow conditions within mixed-flow fan depend on the geometry of the machine (three-dimensional flow effects) and on the properties of the fluid. But most treatments of the problem have been concerned with the two-dimensional flow effects for incompressible, non-viscous fluids. Interest in the field of mixed-flow fan resulted in the undertaking of a program to develop reliable design procedures that would avoid the need for lengthy development work.