• International Journal of Naval Architecture and Ocean Engineering
• /
• 제5권4호
• /
• pp.502-512
• /
• 2013

Simulations of cavitation flow and hull pressure fluctuation for a marine propeller operating behind a hull using the unsteady Reynolds-Averaged Navier-Stokes equations (RANS) are presented. A full hull body submerged under the free surface is modeled in the computational domain to simulate directly the wake field of the ship at the propeller plane. Simulations are performed in design and ballast draught conditions to study the effect of cavitation number. And two propellers with slightly different geometry are simulated to validate the detectability of the numerical simulation. All simulations are performed using a commercial CFD software FLUENT. Cavitation patterns of the simulations show good agreement with the experimental results carried out in Samsung CAvitation Tunnel (SCAT). The simulation results for the hull pressure fluctuation induced by a propeller are also compared with the experimental results showing good agreement in the tendency and amplitude, especially, for the first blade frequency.

• 대한조선학회논문집
• /
• 제45권4호
• /
• pp.353-360
• /
• 2008

A numerical model for the analysis of the marine propeller including wake roll-up is presented. In this study, we apply a higher-order panel method, which is based on a B-spine representation for both generations of the propeller geometry and hydrodynamic solutions, to predict the flow around the propeller blades. The present model is validated by comparison of the experimental measurements. The results show that the present method is able to predict the improved pressure distributions on the blade surface, especially very close to propeller tip regions, where other panel methods without the wake roll-up model give erroneous results.

• 대한조선학회논문집
• /
• 제39권3호
• /
• pp.8-17
• /
• 2002

RANS 방정식의 수치 해법을 사용해서 선박용 추진기 주의의 점성 유동을 계산함으로써 모형 프로펠러 3개(P4119, P4842, KRISO 포드 프로펠러)의 단독 성능을 해석하였다. 프로펠러 단독성능과 날개 압력 분포 그리고 프로펠러 근방의 평균 속도 분포에 대한 본 연구의 수치 해석 결과를 실험 결과와 비교하였으며, 대체로 두 결과가 서로 잘 일치하는 것이 확인되었다. 그러나, 프로펠러 날개 앞날의 압력과 포드 프로펠러의 단독 성능에 대한 본 연구의 결과는 실험 결과와 잘 맞지 않는 것으로 나타났다.

• 해양환경안전학회지
• /
• 제30권1호
• /
• pp.108-117
• /
• 2024

본 연구에서는 너클 라인이 다수 존재하면서 안팎 형상이 비대칭으로 설계된 특이점을 갖는 쌍동선의 자항성능을 예측하기 위해 CFD 해석을 수행하였고, 해석 기법에 따른 차이를 파악하기 위해 MRF(Moving Reference Frame) 기법과 SDM(Sliding Mesh) 기법을 적용하였다. MRF 기법을 적용한 경우에는 time step당 프로펠러를 1˚ 회전시켰고, SDM 기법의 경우 10˚, 5˚, 1˚씩 회전시키며 각 기법별 예측된 자항성능을 비교하였다. 자항점 추정을 위한 몇 가지 프로펠러 회전수에서의 해석 결과 중 프로펠러의 토크는 기법에 따른 차이가 거의 없었지만 추력 및 선체가 받는 저항은 MRF 기법보다는 SDM 기법을 적용했을 때 더 낮게, SDM 기법의 time step당 프로펠러 회전각이 작을수록 높게 계산되었다. 선형 내삽을 통해 추정된 자항점의 프로펠러 회전수, 추력, 토크와 실선 확장법을 사용해 추정된 실선의 전달동력, 반류 계수, 추력 감소 계수 및 프로펠러 회전수도 동일한 경향을 보였으며, 대부분의 자항효율은 반대의 경향을 보였다. 프로펠러 후류의 경우 MRF 기법을 적용했을 때 정확도가 떨어졌고, SDM 기법의 time step당 프로펠러 회전각에 따라 표현되는 후류의 차이는 거의 없었다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제17권3호
• /
• pp.50-59
• /
• 1993

Usually ship is propelled by the conventional propeller. When the conventional propeller is used for ship's propulsion, reduction of propeller noise is big issue in some special vessel. In order to reduce the acoustic noise of the propeller, novel propulsion system named as MHD propulsion system has been studied among researchers. In this paper, thruster characteristic analysis and system analysis of MHD propulsion system have been carried out. Firstly basic experimental apparatus is designed, fabricated and installed and test is carried out. Test results are compared with numerical analysis. It is confirmed that test results agreed with numerical results satisfactorily.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2012년도 추계학술대회 논문집
• /
• pp.562-567
• /
• 2012

Noises from the large scale marine propeller are calculated numerically on non-cavitation condition. The hydrodynamic analysis are carried out by potential based panel method with time marching free wake approach. The distribution of hyrodynamic loads on the propeller surface and noise signals are obtained using the unsteady Bernoulli's equation and the Farasssat formula respectively. It turns out that the noise signal shows strong peak at the blade passage frequency. Noise signals and directivity patterns for both the thickness and the loading noise are compared with each other. The directivity pattern for the loading noise shows minor lobe at the backward side of the rotating disc plane.

• 대한조선학회논문집
• /
• 제54권1호
• /
• pp.10-17
• /
• 2017

This paper deals with a comparison of performance between tip rake propeller and normal propeller in P.O.W condition. In comparison with normal propeller, tip rake propeller is good at preventing occurring negative effect: tip vortex, etc. But, officially formulated information about tip rake propeller doesn't become known. So this paper makes design variables about rake factors and applies them to propeller geometry. And propellers applied design variables are compared with each other about open water propeller efficiency. Also this paper confirms a vorticity reduction at propeller tip.

• 한국해양공학회지
• /
• 제8권1호
• /
• pp.71-83
• /
• 1994

The axial and torsional coupled vibration of marine propeller shafts can be mainly caused by actual shape of the crank shaft and hydrodynamic forces and moments due to propellers : the former leads to stiffness matrix coupling and the latter leads to inertia and damping matrix coupling. In the present paper the characteristics of the coupled vibration of marine propeller shafts due to hydrodynamic coupling is investigated in details. First, the modelling procedure of the system and analysis technique are also developed. To verify the present method the numerical calculations were also performed. Finally, the results were compared with existing data in the literature and it was found to be in good agreement.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2002년도 춘계학술대회 논문집
• /
• pp.231-236
• /
• 2002

By using the infinite dimensional optimization[Jang and Kinoshita(2000)]. which is based on the Hilbert space theory, optimal marine propellers are studied. The mathematical uniqueness for the optimized propeller is shown in this study. As a numerical example, the MAU type propeller is considered and used as the initial guess for the optimization method. The numerical results for an optimal marine propeller is illustrated for the pitch distribution.

• 한국정밀공학회지
• /
• 제17권9호
• /
• pp.53-61
• /
• 2000

The manufacture of a marine propeller typically requires long lead time to generate 5-axis tool path. Hence it may take several weeks to manufacture a satisfactory propeller with a general purpose CAD/CAM system. In this research a dedicated 5-axis CAD/CAM system for machining marine propellers has been developed, The system employs various methods to enhance the productivity : interference-free tool path generation employing check vectors and optimum cutter size determinants. In addition an iterative NURBS modeling technique is used to improve the accuracy of the modeled surface and effective cutting conditions are determined and recommended empirically to increase the productivity. The proposed CAD/CAM system has been implemented with C++ and OpenGL graphic library on the Windows system. The system validation and sample results are also given and discussed.