• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.3
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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.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.4
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• pp.310-315
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• 2017

Recently constructed ships are equipped with high efficiency propeller for low fuel consumption and comfortable operation. Based on the torsional vibration analysis of the shaft system of the high efficiency propeller, using the propeller damping method considering the characteristics of previous propeller designs, a considerable amount of analysis errors are found to be generated. These errors are expected to increase as the development of high efficiency vibration propellers continues. In this paper, errors in torsional vibration analysis, in accordance with various propeller damping methods, are reviewed. In addition, a propeller damping method suitable for use at present is suggested by reviewing the comparison results of analysis and measurement values according to the propeller damping methods for vessels adopting the high efficiency direct-coupled propeller with 10MW class.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.123-128
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• 2016

The effect of propeller surface roughness condition on ship performance is very significant even the influence of fouling on propeller performance is not well established compared to biofouling on the hull surface. In present study, predictions of open water efficiency of propeller are made for three different fouling conditions, and its application is given for the 7m full-scale propeller of a medium-size tanker in open water condition. The numerical predictions of propeller efficiency loss due to fouling are based on the results from laboratory-scale drag measurements and boundary layer similarity law analysis presented in Schultz (2007) together with an in-house unsteady lifting surface code which is an appropriate tool to predict the effect of propeller surface roughness on propeller performance. The results of this study indicate that the subject propeller with the small calcareous fouling ($k_s=0.001$) can lead to as high as 15 % loss at the propeller operating condition (J=0.5) and the loss of propeller efficiency due to fouling should be evaluated while the ship is operating.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.6
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• pp.453-460
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• 2017

In order to investigate propulsion efficiency and cavitation characteristics for expanded area ratio variation of the 8800TEU class container propeller, a series of performance tests were conducted at Large Cavitation Tunnel (LCT) and Towing Tank (TT) in KRISO. The cavitation test of the existing propellers (KP1029 & KP1030) was conducted using FRP model ship in LCT. On the basis of LCT test results, it was required to design propeller with better propulsion efficiency and cavitation performance. Two propellers (KP1171 & KP1172) with decreased expanded area ratio were designed on the basis of KP1029 propeller. The new design propellers showed higher efficiency than KP1029 and reasonable cavitation performance. In the future, they will be applied as the standard propeller for the propeller design of the large container ship. Through the performance test and prediction results for the new design propellers, it is thought that high-load propeller with better propulsion efficiency and cavitation performance will be developed constantly.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.4
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• pp.476-486
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• 2010

Fishing efficiency of a trawl vessel can be enhanced by increasing the swept area per unit time, which can be attained either by increasing the mouth size of the net, or by increasing the towing speed. To improve fishing and fuel efficiency of trawl vessels targeting fishes of greater mobility, in which the towing speed is more critical in determining fishing efficiency, we conducted a series of model tests to evaluate the performance of the newly-designed nozzle propeller before installing it in a trawl vessel to verify its towing speed and fuel efficiency in the sea. By conducting further model tests in the experimental basin, we redesigned the propeller of stern trawler to improve the resistance and propulsion performance. Through actual fishing operations, we evaluated the improvement in fuel and fishing efficiency by installing the new nozzle propeller. The trawling speed increased by 0.6kts at the same engine power (RPM), while the engine margin increased by more than 20%. The increased towing speed by installing the redesigned propeller is expected to enhance fishing performance through increasing the number of hauling- and casting operations per unit times, while shortening the towing duration. Analysis of the Catch-Per-Unit-Effort (CPUE) data indicated that the mean CPUE of trawl fishery increased from 3.04kg/m in year 2007 to 6.15kg/m in year 2008, confirming enhanced fishing efficiency by adopting the redesigned propeller.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.132-145
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• 1992

A series of design, theoretical analysis and model test procedures is presented for the development of an axisymmetric stator-propeller system. A preswirl stator is located in front of a propeller in order to improve the propulsion efficiency by cancellation of the slip stream rotational velocity due to the propeller. Model test results show that propulsion efficiency gain due to the symmetric stator-propeller system is about 3% compared to the single propeller. This efficiency gain would increase for full scale application since the pressure drag coefficient of the stator would decrease due to increasement of turbulent intensity behind the hull wake and increasement of Reynolds number.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.6
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• pp.416-423
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• 2023

Recently, the design point of the propeller is gradually changing due to the demand for energy saving and environmental protection. Until recently, self-propulsion model tests were conducted using stock propellers and geometry information was provided to propeller designers, but the range of existing stock propellers did not keep up with the changing design points, and the range of series propellers required in the initial design was also insufficient. Future propeller performance requires high performance and eco-friendliness, and the need for expansion of series propellers has increased. In order to respond to future needs and provide a wide range of advantages in propeller design, KRISO manufactures about 100 series propellers and builds series data through a model tests. In this paper, the approach method for deriving the representative optimal shape to be applied to the 4-blade series propeller in the initial stage of series propeller development was summarized.

• Journal of Ocean Engineering and Technology
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• v.37 no.5
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• pp.181-189
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• 2023

The fuel consumption of marine diesel engines holds paramount importance in contemporary maritime transportation and shapes energy efficiency strategies of ocean-going vessels. Nonetheless, a noticeable gap in knowledge prevails concerning the influence of ship hull conditions and propeller roughness on fuel consumption. This study bridges this gap by utilizing artificial intelligence techniques in Matlab, particularly convolutional neural networks (CNNs) to comprehensively investigate these factors. We propose a time-series prediction model that was built on numerical simulations and aimed at forecasting ship hull and propeller conditions. The model's accuracy was validated through a meticulous comparison of predictions with actual ship-hull and propeller conditions. Furthermore, we executed a comparative analysis juxtaposing predictive outcomes with navigational environmental factors encompassing wind speed, wave height, and ship loading conditions by the fuzzy clustering method. This research's significance lies in its pivotal role as a foundation for fostering a more intricate understanding of energy consumption within the realm of maritime transport.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.4
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• pp.266-274
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• 2016

Many researchers have been trying to improve the propulsion efficiency of a propeller. In this study, the numerical analysis is carried out for the POW(Propeller Open Water test) performance of a propeller equipped with an energy saving device called PHVC(Propeller Hub Vortex Control). PHVC is aimed to control the propeller hub vortex behind the propeller so that the rotational kinetic energy loss can be reduced. The unsteady Reynolds Averaged Navier-Stokes(URANS) equations are assumed as the governing flow equations and are solved by using a commercial CFD(Computational Fluid Dynamics) software, where SST k-ω model is selected for turbulence closure. The computed characteristic values, thrust, torque and propulsion efficiency coefficients for the target propeller with and without PHVC and the local flows in the propeller wake region are validated by the model test results of KRISO LCT(Large Cavitation Tunnel). It is concluded from the present numerical results that CFD can be a good promising method in the assessment of the hydrodynamic performance of PHVC in the design stage.

• The KSFM Journal of Fluid Machinery
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• v.19 no.2
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• pp.11-15
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• 2016

In this study, the generation of the propeller hub vortex was analyzed and a PBCF(Propeller Boss Cap Fins) was designed to control the propeller hub vortex. A RANS(Reynolds-averaged Navier-stokes) approach is employed to predict the hub vortex characteristics. The hub profile is an important factor but only a small increase (1.9%) of efficiency was obtained with the hub profile modification. The propeller hub vortex was eliminated by installing the PBCF and as a result, the propeller efficiency was increased by 5.6%.