• 한국해양공학회지
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• 제26권6호
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• pp.39-45
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• 2012

Underwater robots are generally used for the construction of seabed structures, deep-sea ecosystem research, ocean energy development, etc. A ducted marine propulsor is widely used for the thruster of an underwater robot because of its collision protection, efficiency increase, cavitation reduction, etc. However, the flow of a ducted propeller is very complex because it involves strong flow interactions between the blade impeller and duct. The present work aimed to design a ducted propeller using 2-D strip theory and CFD analysis. The hydrodynamic forces (i.e. and ) were computed to set the local angle of attack in a spanwise direction of the propeller blade. After the propeller design, performance coefficients such as the thrust, torque, and efficiency were computed to check whether the designed performance was achieved. To validate the present analysis, the thrust was compared with experimental data and good agreement was obtained.

• 설비공학논문집
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• 제9권1호
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• pp.14-22
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• 1997

The position of propeller fan from duct inlet is one of basic parameters for the design of propeller fan. To investigate the effect of its position on fan characteristics, the inlet flow fields and relative flow angles were measured by a 5-hole pitot tube. The experimental results indicate that the ratio of radial flow introduced from propeller circumference to total inlet flow increases with the increase of propeller distance from duct inlet. When fan operates without duct, the total flow rate and the radial flow ratio are higher than those of any other positions of propeller relative to duct inlet. The radial flow ratio decreases as a flow coefficient and the propeller distance decrease. Therefore the front flow fields can be adjusted in some extent by varying the propeller distance according to a fan loading. The inlet flow angles are decreasing a little as a rotational speed and the propeller distance decrease. In the present case it was judged that the deviation angle of outlet flow became negative owing to a flow separation near a trailing edge.

• 한국항공우주학회지
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• 제38권10호
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• pp.955-965
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• 2010

초소형 무인기 추진용 MH-75 프로펠러는 자유와 설계기법을 이용하여 설계변수인 허브팁 비, 비틀림각 분포, 최대 캠버의 위치와 크기 그리고 시위 길이를 변화시키며 설계 요구조건을 만족하도록 공력설계 되었다. MH-75 프로펠러는 주파수영역 패널법을 이용하여 설계요구조건을 만족시키고, 다양한 초소형 무인기에 적용이 가능하도록 정지추력 특성과 비행속도 및 회전수 변화에 따른 성능 특성을 예측하였다. 그리고 MH-75 프로펠러의 공력해석 결과를 검증하기 위해 프로펠러의 추력특성에 대한 풍동시험을 수행하였다. MH-75 프로펠러의 추력 성능은 설계요구조건을 만족하였으며, 저레이놀즈 수 영향을 고려하기 위한 2차원 익형 해석용 XFOIL 프로그램에 비해 3차원 효과를 고려하는 주파수영역 패널법을 이용하는 것이 비교적 풍동시험 결과와의 오차가 적음을 확인하였다.

• 수산해양기술연구
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• 제52권4호
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• pp.347-355
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• 2016

In this study, a new designed propeller was applied on 24 ton class squid jigging vessel to reduce of fuel consumption. The selected squid jigging boat was under construction at the shipyard to determine the resistance of the hull through the model experiment. The propeller design was carried out by using the experimental data and ITTC procedures. Sea trials were performed by measuring the speed and the horsepower required by the condition of five power levels of engine load, namely 70%, 80%, 90%, MCR and maximum engine power. The speed and delivered horse power were compared between the conventional propeller and the new design propeller. Delivered horse power by installing the new propeller takes 90% engine load at start-up conducted by decreased 9.06%. The measuring speed is increased up to the 0.6 knots in the low-speed range to high range. This study showed that only the design and installation of a new propeller can improve the propulsion efficiency of the boats; furthermore, reduce fuel costs can be achieved at the same time by improving the increased cruising speed.

• 한국항해학회지
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• 제14권3호
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• pp.15-33
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• 1990

In recent years, propellers with various blade configurations such as highly skewed propellers are often fitted to ships from the viewpoint of reduction of vibration and noise. In the design of such propellers, design charts based on methodical series tests are to be complemented by theoretical calculations for accurate estimation of propeller open-water characteristics. The author intended to develop a method to estimate propeller open-water characteristics based on Quasi -Vortex - Lattice Method originally developed by Lan for solving planar thin wings, The Quasi - Vortex - Lattice Method has the simplicity and flexibility of Vortex - Lattice Method. Its accuracy is comparable to that of the Vortex - Lattice Method. Converged solution can be obtained with a small number of control points and further, leading edge suction force can be calculated directly. In the present paper, a numerical method to estimate propeller open-water characteristics based on the Quasi - Vortex - Lattice Method is reviewed and its application to marine propellers is described in detail. Comparison of propeller open-water characteristics obtained by the present method with experimental data showed good agreement for a wide variety of propellers including highly skewed propellers.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1081-1086
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• 2008

During the manufacturing process of a propeller for a large scale commercial ships, several times of turn-over process should be required. Propeller turn-over is a indispensible process but not easy because of its heavy weight and complicate shape. Recently, we developed a new type of turn-over system for a large scale propeller. The system consists of turning roller devices, sliding transfer system, clamping devices and so on. In this paper, we described the design process which includes mechanical structure design, dynamic analysis and assembly with a laser tracker.

• International Journal of Naval Architecture and Ocean Engineering
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• 제1권1호
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• pp.29-38
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• 2009

A ship's screw-propeller produces thrust by rotation and, at the same time, generates rotational flow behind the propeller. This rotational flow has no contribution to the generation of thrust, but instead produces energy loss. By recovering part of the lost energy in the rotational flow, therefore, it is possible to improve the propulsion efficiency. The contra-rotating propeller (CRP) system is the representing example of such devices. Unfortunately, however, neither a design method nor a full-scale performance prediction procedure for the CRP system has been well established yet. The authors have long performed studies on the CRP system, and some of the results from the authors' studies shall be presented and discussed.

• 대한조선학회논문집
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• 제49권6호
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• pp.528-533
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• 2012

Flexible composite propellers are subject to large deformation under heavy loading, and hence the hydrodynamic performance of deformed propeller might deviate from that of the metallic propeller under negligible deformation. To design the flexible propeller, it is therefore necessary to be able to evaluate the structural response of the blades to the hydrodynamic loadings, and then the influence of the blade deformation upon the hydrodynamic loadings. We use the lifting-surface-theory-based propeller analysis and design codes in solving the hydrodynamic problem, and the finite-element-method program formulated with 20-node iso-parametric solid elements for the analysis of the structural response. The two different hydrodynamic and structural programs are arranged to communicate through the carefully-designed interface scheme which leads to the derivation of the geometric parameters such as the pitch, the rake and the skew distributions common to both programs. The design of flexible propellers, suitable for manufacturing, is shown to perform the required thrust performance when deformed in operation. Sample design shows the fast iteration scheme and the robustness of the design procedure of the flexible propellers.

• 한국해양공학회지
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• 제25권4호
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• pp.48-53
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• 2011

Current trends in propeller design have led to the need for extremely complex blade shapes, which place great demands on the accuracy of design and analysis methods. This paper presents a new proposal for improving the prediction of propeller performance with a vortex lattice method using the lifting surface theory. The paper presents a review of the theory and a description of the numerical methods employed. For 8 different propellers, the open water characteristics are calculated and compared with experimental data. The results are in good agreement in the region of a high advanced velocity, but there are differences in the other case. We have corrected the parameters for the trailing wake modeling in this paper, and repeated the calculation. The new calculation results are more in agreement with the experimental data.

• Journal of Advanced Research in Ocean Engineering
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• 제4권2호
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• pp.78-85
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• 2018

This paper presents a study of the effects of the free surface to marine propeller including the mesh effect of the models. In the present study, we conduct the numerical simulation for propeller performance employing the openwater test. The numerical simulations compare the meshing strategies for the propeller and show the effects on both thrust and torque. OpenFOAM is applied to solve the propeller problem and then open water performances of KCS propeller (KP505) are estimated using a Reynold-averaged Navier-Stokes equations (RANS) solver and the turbulence of the $K-{\omega}$ SST model. Unstructured meshes are used in the numerical simulation employing hexahedral meshing for mesh generation. The arbitrary mesh interfacing (AMI) and multiple rotating frame (MRF) are compared to define the best meshing strategy. The meshing strategies are evaluated through 3 classifications, i.e., coarse, medium, and fine mesh. Thus, the propeller can be performed utilizing the best mesh strategy. The computational results are validated by comparison with the experimental results. The $K_T$, $K_Q$, and efficiency of the propeller are compared to an experimental result and for all of the meshing strategies. Thus, the simulations show the influence of meshing in order to perform the propeller performances.