• Ocean Systems Engineering
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• 제2권2호
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• pp.83-97
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• 2012

In the present work, design procedure and computer simulation of an AUV are documented briefly. The design procedure containing the design of propulsion system and CFD simulation of hydrodynamics behavior of the hull leads to achieve an optimum mechanical performance of AUV system. After designing, a comprehensive one dimensional model including motor, propeller, and AUV hull behavior simulates the whole dynamics of AUV system. In this design, to select the optimum AUV hull, several noses and tails are examined by CFD tools and the brushless motor is selected based on the first order model of DC electrical motor. By calculating thrust and velocity in functional point, OpenProp as a tool to select the optimum propeller is applied and the characteristics of appropriate propeller are determined. Finally, a computer program is developed to simulate the interaction between different components of AUV. The simulation leads to determine the initial acceleration, final velocity, and angular velocity of electrical motor and propeller. Results show the final AUV performance point is in the maximum efficiency regions of DC electrical motor and propeller.

• 대한조선학회논문집
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• 제60권4호
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• pp.231-239
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• 2023

In order to improve the propeller Cavitation Inception Speed (CIS) performance, it needs to modify the propeller geometry and the wake distribution that flows into the propeller. In the previous study, the twisted angles of the V-strut were modified to improve propeller CIS, cavitation behavior and pressure fluctuation performances. Then the propeller behind the modified V-strut (New strut) showed better cavitation characteristics than that behind the existing V-strut (Old strut). However, the CIS of Suction Side Tip Vortex (SSTV) and Pressure Side Tp Vortex (PSTV) showed a big difference at behind each V-strut. In this study, the balance design is conducted to minimize the difference between SSTV CIS and PSTV CIS at behind each V-strut. To improve the propeller CIS performance, 1 propeller is designed at behind the old strut and 3 propellers are designed at behind the new strut. The propeller CIS is increased through the balance design and the stern appendage modification. The final propeller CIS is increased about 5.3 knots higher than that of the existing propeller at behind the old strut. On the basis of the present study, it is thought that the better improvement method for the propeller CIS would be suggested.

• 대한조선학회논문집
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• 제57권2호
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• pp.61-69
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• 2020

Due to its flexibility of the composite propeller blade, it is necessary to design a shape capable of generating a desired load at a design point in consideration of the shape change of the propeller. In order to design it, we need to evaluate not only the hydrodynamic force around it, but also its structural response of flexible propeller according to its deformation. So, it is necessary to develop a design tool to predict the hydroelastic performance of a flexible propeller with deformation considering fluid-structure interaction and special operating conditions. Finally a design optimization tool for flexible propellermade of CFRP is required. In this study, a design methodology of the specific flexible composite propeller is suggested, considering fluid-structural interaction analysis of the specific flexible propeller.

• 해양환경안전학회지
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• 제20권3호
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• pp.296-303
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• 2014

The Axiom propeller is a unique 3 bladed propeller and it enables to generate the same amount of thrust going ahead as it does going astern because of its 's' type skew-symmetric blade section. A earlier variant of the design (Axiom I propeller) performed a low propeller efficiency, maximum 35 % efficiency, and further blade outline design was carried out to achieve a higher efficiency. The optimized new blade outline (Axiom II propeller) has more conventional Kaplan geometry shape than Axiom I propeller. Model tests of open water performance and propeller cavitation for both propellers were conducted at Emerson Cavitation Tunnel in order to compare their performances. Experiment results revealed that Axiom II propeller provides a maximum 53 % efficiency and provides better efficiency and cavitation performance over the Axiom I propeller under similar conditions.

• 대한조선학회논문집
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• 제54권1호
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• pp.10-17
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• 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.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.918-927
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• 2020

Flows induced by hybrid CRP pod propulsion systems (CRP-POD) are fundamentally characterized by unsteadiness. This work presents a numerical study on the unsteady flow of a CRP-POD at behind-hull condition based on CFD (Computational Fluid Dynamics). Unsteady RANS method is adopted, coupled with SST k-u turbulence model and sliding mesh method. The propeller thrusts and torques obtained by CFD is validated by model tests and acceptable agreements are obtained. The time histories of shingle-blade loads and pressures near the hull surface are recorded for the analysis of unsteady flow features. The cases of forward propeller alone and aft propeller alone are also computed to distinguish the hull-propeller interaction and propeller-propeller interaction. The results show the blade loads of both forward and aft propellers strongly fluctuate with phase angles. For the forward propeller, the blade load fluctuation is mainly governed by the hull-propeller interaction, while the aft blade load is remarkably affected by the propeller-propeller interaction in terms of the load average and fluctuation pattern. The fields of pressure, vorticity and velocity are also analyzed to reveal the unsteady flow features.

• 한국항공우주학회지
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• 제40권12호
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• pp.1017-1024
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• 2012

깃끝단 후퇴각을 가지는 최신 터보프롭 항공기의 프로펠러 블레이드에 대한 공력설계 및 해석을 수행하였다. 프로펠러 형상 설계를 위한 익형은 HS1 계열을 적용하였다. 와류-깃요소 이론(Vortex-Blade element theory)을 기반으로 하고 최소에너지 손실 조건을 만족하는 Adkins의 방법을 적용하여 Conventional 프로펠러 블레이드에 대한 공력설계 및 성능해석을 하였다. 목표 항공기의 설계점에서 코드 길이와 피치각을 변경해 가며 프로펠러 형상을 생성하였다. Conventional 프로펠러 블레이드 형상 정보를 기반으로 코드 길이, 깃끝단 후퇴각을 수정 적용하여 최신 프로펠러를 설계하였다. 전산유체역학을 이용한 설계된 최신 프로펠러 공력특성 분석을 통하여 최신 프로펠러가 적절하게 설계되었음을 확인하였다.

• 대한조선학회지
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• 제22권2호
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• pp.35-48
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• 1985

The present work develops a method of evaluating thrust deduction and wake for different loads of the propeller using the concerted application of the theoretical tools and experimental techniques. It also shows the applicability of the new method to the design of optimum hull form. Firstly, the problem of hull-propeller interaction was analyzed in terms of inviscid as well as viscous components of the thrust deduction and wake. The wavemaking resistance of a hull and propeller were mathematically represented by sources on the hull surface and sink on the propeller plane, respectively. The strength of sink was determined by utilizing the radial distributions of propeller load and nominal wake. The resistance increment due to a propeller and the axial perturbation flow induced by the hull in the propeller plane were calculated. Especially, the inviscid component of the thrust deduction was calculated by subtraction the wavemaking resistance of a bare hull, the wavemaking resistance of a free-running propeller and the augmentation of propeller resistance due to hull action from the wavemaking resistance of the hull with a propeller. The viscous components of the thrust deduction and wake were estimated as functions of propeller load which were established by the propeller load varying test after deduction the calculated inviscid components. Secondly, an analysis method of powering performance was developed based on the potential theory and the propeller load varying test. The hybrid method estimates the thrust deduction, wake and propeller open-water efficiency for different propeller load. This method can be utilized in the analysis of powering performance for the propeller load variation such as the added resistance due to hull surface roughness, the added resistance due to wind, etc. Finally, the hybrid method was applied to the optimum design of hull form. A series of afterbody shapes was obtained by systematically varying the waterplane and section shapes of a parent afterbody without changing the principal dimensions, block coefficient and prismatic coefficient. From the comparison of the predicted results such as wavemaking resistance, thrust deduction, wake and delivered power, an optimum hull form was obtained. The delivered power of the optimized hull form was reduced by 5.7% which was confirmed by model tests. Also the predicted delivered power by the hybrid method shows fairly good agreement with the test result. It is therefore considered that the new analysis method of powering performance can be utilized as a practical tool for the design of optimum hull form as for the analysis of powering performance for the propeller load variation in the preliminary design stage.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권3호
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• pp.246-255
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• 2017

The proposed design methodology represents a new approach to optimize the propeller-hull system simultaneously. In this paper, two objective functions are considered, the first objective function is Lifetime Fuel Consumption (LFC) and the other one is cost function including thrust, torque, open water and skew efficiencies. The variables of the propeller geometries (Z, EAR, P/D and D) and ship hull parameters (L/B, B/T, T and $C_B$) are considered to be optimized with cavitation, blades stress of propeller. The well-known evolutionary algorithm based on NSGA-II is employed to optimize a multi-objective problem, where the main propeller and hull dimensions are considered as design variables. The results are presented for a series 60 ship with B-series propeller. The results showed that the proposed method is an appropriate and effective approach for simultaneously propeller-hull system design and is able to minimize both of the objective functions significantly.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.648-651
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• 2010

FAR25급 터보프롭 항공기에서 프로펠러는 고속으로 비행할 수 있는 추력을 얻기 위해 공기역학적으로 우수하며 높은 효율을 가져야 한다. 프로펠러 형상 설계를 위한 익형은 전형적인 터보프롭 항공기 프로펠러에 사용되는 Clark-Y를 적용하였다. 프로펠러 공력설계 및 해석에는 최소에너지손실을 위한 조건을 만족시키도록 설계하는 와류-깃요소 이론(Vortex-Blade element theory)에 근거한 Adkins의 방법을 이용한 Javaprop을 이용하였다. 시위길이와 피치각 분포를 변경해 가며 FAR25급 터보프롭 항공기의 설계점에 가장 효율적인 프로펠러 형상을 생성하였으며, 전산유체역학을 이용하여 생성된 프로펠러 공력특성 분석을 통해 프로펠러 설계결과가 FAR25급 터보프롭 항공기에 적용 가능함을 확인하였다.