• Journal of Aerospace System Engineering
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• v.13 no.3
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• pp.56-63
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• 2019

Performance analyses were performed on a propeller developed for use in a PAV (Personal Air Vehicle) under 600 kg Maximum Take-Off Weight (MTOW). The actuator disc theory and CFD analyses were used to estimate the hovering time with regards to MTOW variation for a given battery weight. The interference induced power factor kint was introduced to account for the effect of flow interference between the propellers and to estimate the performance of counter-rotating propellers. The Maximum Figure of Merit (FM) value of the propeller pitch was determined and the design RPM range for the required power inversely obtained from the CFD results. Previous research indicate that the flight time of large multi-copter is limited by the available battery energy density. Similarly, the propeller pitch settings and spacing are important factors in reducing the kint value.

• Bulletin of the Society of Naval Architects of Korea
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• v.32 no.3
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• pp.12-18
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• 1995

본 고에서는 중소형 선박의 초기설계시 필요로 하는 종합적인 저한추진성능 추정 프로그램을 다루고자 한다. 국내의 중소형 선박 설계자들이 많이 사용하고 있는 도표 및 회귀식을 선종별로 고루 모아서 손쉽게 사용할 수 있도록 전산화하였다. 이 프로그램에는 저항추진계수의 추정, 프로펠러의 간략한 설계 및 단독효율 추정, 전달동력과 회전수의 추정이 포함되어 있다.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.1
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• pp.50-59
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• 1997

Shipbuilder checks the status of main engine and propeller operation before sea trial. Generally these tests are carried out at a quay during fitting out of the ship. For these tests the operator has to estimate the maximum RPM with permissible torque and thrust to ensure the safety of the mooring line and ship. In this paper, the propeller characteristics according to the draft variation for a moored ship is inveatigated. From these tests, it is shown that shaft submergence is a dominant parameter in the propeller performance at shallow shaft submergence and that the propeller performance is dependent upon the propeller RPM when the shaft submergence is kept unchanged. In this study, a simple formula of the required thrust for a given propeller shaft submergence and propeller RPM is derived. 1be propeller thrust, which is calculated by another formula in case of dtep draft, is compared with results of bollard pull test for FPSO.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.1
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• pp.73-86
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• 1993

This paper describes a potential-based panel method for the prediction of steday performance of a marine propeller operating in a uniform oncoming flow. An integral equation with unknown dipole strengths is formulated by distributing the normal dipoles and/or sources on the blade and hub surfaces and the wake sheet, and is solved numerically upon discretization. A hyperboloidal panel has been adopted to compute the potential induced by a normal dipole on a non-planar quadrilateral panel. The Kutta condition is satisfied by iteratively annulling the pressure jumps at the trailing edge. Extensive convergence tests are carried out, and the influence of the wake model upon performance is studied. Predicted performance is shown to correlate well with the experiments.

• Journal of Korea Fishing Vessel Association
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• v.29
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• pp.31-39
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• 1986

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.108-117
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• 2024

In this study, simulations based on computational fluid dynamics were performed for self-propulsion performance prediction of a catamaran that has asymmetrical inside and outside hull form and numerous knuckle lines. In the simulations, the Moving Reference Frame (MRF) or Sliding Mesh (SDM) techniques were used, and the rotation angle of the propeller per time step was different to identify the difference using the analysis technique and condition. The propeller rotation angle used in the MRF technique was 1˚ and those used in the SDM technique were 1˚, 5˚, or 10˚. The torque of the propeller was similar in both the techniques; however, the thrust and resistance of the hull were computed lower when the SDM technique was applied than when the MRF technique was applied, and higher as the rotation angle of the propeller per time step in the SDM technique was smaller in the simulations for several revolutions of the propeller to estimate the self-propulsion condition. The revolutions, thrust, and torque of the propeller in the self-propulsion condition obtained using linear interpolation and the delivered power, wake fraction, thrust deduction factor, and revolutions of the propeller obtained using the full-scale prediction method showed the same trend for both the techniques; however, most of the self-propulsion efficiency showed the opposite trend for these techniques. The accuracy of the propeller wake was low in the simulations when the MRF technique was applied, and slight difference existed in the expression of the wake according to the rotation angle of the propeller per time step when the SDM technique was applied.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.2
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• pp.68-74
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• 1995

The statistical analysis system is necessary to predict the resistance and powering performance quickly and precisely at the initial design stage. The authors propose the several functions of the performance prediction program and the structures of data bank. The program includes several series charts, regression coefficients and adapted regression analysis method based on the data bank to predict the resistance and propulsive coefficients. The calculation procedure to find out the principal dimensions and open-water efficiency of the optimum propeller is also included. The evaluation for the program and data bank is conducted by the arbitrarily selected 14 ship models. The results show good agreement with experiments within 5% mean prediction error.

• The Journal of the Acoustical Society of Korea
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• v.42 no.6
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• pp.529-535
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• 2023

Noise originating from incipient propeller cavitation is assumed to come from a limited number of sources emitting a broadband signal. Conventional methods for cavitation localization have limitations because they cannot distinguish adjacent sound sources effectively due to low accuracy and resolution. On the other hand, sparse Bayesian learning technique demonstrates high-resolution restoration performance for sparse signals and offers greater resolution compared to conventional cavitation localization methods. In this paper, an incipient propeller cavitation localization method using sparse Bayesian learning is proposed and shown to be superior to the conventional method in terms of accuracy and resolution through experimental data from a model ship.

• Journal of Ocean Engineering and Technology
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• v.24 no.4
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• pp.66-71
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• 2010

Numerical prediction of propeller performance plays an important role in a marine propeller design process. Program developers are consistently trying to improve diminish predicted errors, and program users need to keep up with the latest ones with minimum expenditure of time and money. We have developed an internet based design system in which clients can design propellers with remote access. In this paper, optimized Internet based Propeller Design and Analysis System (iProDAS) for transferences of the massive data is presented, and a sample design using iProDAS is examined.

• Journal of Navigation and Port Research
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• v.46 no.3
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• pp.168-178
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• 2022

In this study, the resistance test, the vertical static angle of the attack test and VPMM test will be conducted to estimate the maneuverability of underwater vehicles with ahead propeller. The vertical static test will be conducted within the range of -40deg to 40deg, to investigate the cross-flow drag at high incidence angles. The tests will be conducted by dividing the propeller rotation into a case in which the propeller rotates at a specific rpm, and a case in which the propeller rotates naturally, according to the towing speed. Hydrodynamic coefficients of vertical direction will be estimated by the captive model tests. Additionally, the vertical dynamic stability index based on estimated hydrodynamic coefficients will be calculated and the impact of the propeller revolution state on the index will be investigated. The results are expected to be used as reference test data for underwater vehicles with ahead propeller.