• Journal of the Society of Naval Architects of Korea
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• v.53 no.6
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• pp.494-502
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• 2016

The accurate assessment of hull-appendage interaction in the early design stage is important to control the inflow to the propeller plane, which can cause undesirable hydrodynamic effects in terms of cavitation phenomenon. This paper describes a numerical analysis for the flow around a fully appended surface ship model for which KRISO has carried out a model test in the Large Cavitation Tunnel(LCT). This numerical study was performed with the LCT model test in a complementary manner for a good reproduction of the wake distribution of surface ships. A second order accurate finite volume method provided by a commercial computational fluid dynamics(CFD) program was used to solve the governing Reynolds Averaged Navier-Stokes(RANS) equations, where the SST $k-{\omega}$ model was used for turbulence closure. The numerical results were compared to available LCT experimental data for validation. The calculations gave good predictions for the boundary layer profiles on the walls of the empty cavitation tunnel and the wake at the propeller plane of the fully appended hull model in the LCT.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.2
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• pp.39-45
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• 2005

The aim of this research is to predict the thickness and loading noise of the round-tip shaped Hartzell propeller currently used in the general aviation aircraft. Before implementing the noise analysis, the pressure distribution on the propeller was obtained by using the free wake panel method and unsteady Bernoulli's equation. The noise signal at observer position can be obtained by using the FW-H equation. The noise prediction results for the propeller indicates that the thickness noise has s symmetric directivity pattern with respect to the tip path plane, while the noise due to loading shows higher noise directivity toward downstream than the upstream direction from the rotor plane. The loading noise is dominant rather than the thickness noise in normal operating condition.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.1
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• pp.80-87
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• 1998

This paper deals with the evaluation of structural safety to fatigue strength of marine propeller blades having high skew angle and operating in irregular wake field. The determination of the optimum skew angle of a propeller blade is one of the important task at the initial design stage especially in the case of high speed vessel such as container ships. A computer program system has been developed to evaluate the structural safety to fatigue strength and has been applied to several propeller blades with varying skew angle within a wide range. In the parametric study the pressure acting on the blade surface is calculated using the non-lineal lifting surface theory and the structural analysis is performed using MSC/NASTRAN. The relationship between skew angle and structural safety to fatigue strength is investigated and this paper ends with describing the optimum skew angle of a propeller blade.

• Bulletin of the Society of Naval Architects of Korea
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• v.22 no.2
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• pp.12-26
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• 1985

This paper describes the experimental method to predict the propeller induced fluctuating pressure on the hull surface. Cavitations of the three model propellers with varying degree of skews, $0^{\circ},\;36^{\circ}\;and\;72^{\circ}$, were observed and the fluctuating pressure induced by the cavitating propellers in the flat plate above these propellers were measured simultaneously at 9 points in the wake field generated by the wire-mesh screens. Another model propeller designed for the dummy model ship was tested in a similar way behind the dummy model ship. The effects of skew variation on the cavitation patterns and fluctuating pressures were illustrated, and the influence of tip-clearances on the fluctuating pressures was also demonstrated. As a result, it is shown that the level of fluctuating pressure and cavity extent could be controlled to some extent by introducing the skews and tip clearances.

• Journal of the Korean Society of Visualization
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• v.19 no.2
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• pp.48-55
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• 2021

In order to design a propeller with high efficiency and excellent cavitation performance, theoretical and experimental studies on the cavitation and noise characteristics according to the blade section shape are essential. In general, sheet cavitation, bubble cavitation, and cloud cavitation are the main causes of hull vibration and propeller surface erosion. However vortex cavitation, which has the greatest influence on the noise level because the fastest CIS in ship propeller, has been researched for a long time and studies have been conducted recently to control it. In this experiment, the development process of cavitation was measured by using three dimensional wings with two different wing section and wing tip shapes, and the noise level at that time was evaluated. In addition, we evaluated the relationship between cavitation inception and hydrodynamic force using three component load cell and we measured the velocity field of wing wake using LDV.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.2
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• pp.81-89
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• 2019

In this study, wind tunnel test on Quad-Tilt Propeller which has tandem wings is carried out to analyze the aerodynamic interference effect of front wing and propeller on rear wing during forward flight. Using 6-axis balance system, forces and moments of whole aircraft were measured and using strain gauge at wing root, bending moments were measured to observe change of aerodynamic force of each wings. A 12-hole probe was used to measure the flow field in the wing and propeller wake. Flow characteristics were observed qualitatively through flow visualization experiment using tuft and smoke. To measure the aerodynamic interference by elements, the influence of front wing and propeller on rear wing was analyzed by changing the wings and propellers mount combination.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.5
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• pp.453-459
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• 2009

The DSME guide plate(GP) has been developed with the target to improve the cavitation and vibration performance when used with discharging cooling water around the outlet of LNG carrier. It was proven that it could as well be applied as a powerful wake control device on its own, even without discharging cooling water. However, it has to be taken into account that it inevitably results in speed loss. This study shows the possibility to design a GP which simultaneously improves both vibration and speed performance. The study intends to outline how to design the preliminary GP configurations from both the vibration and the speed performance points of view. Further, the study offers design guidance for the hull form and the propeller when adapting GP as a wake control device.

• Journal of the Korean Society of Safety
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• v.10 no.1
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• pp.3-8
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• 1995

The anemometer measurements were obtained from stationary hot-film probe mounted between the forward and rear rotors of a model CRP which rotated the forward and different directions. Data collection was done at several locations between rotors. To establish rotor-rotor interaction flow mechanism that contributes noise increasement of the CRP, methods of simple and the double condition-at sampling have been developed. The former uses to find similarity of the wake the later fixes the forward rotor position in time or space and permits averaging the mean wake at any fixed rotor angular location. The variation of the forward wake Is strongly depending upon the rear rotor location.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.6 s.144
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• pp.593-600
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• 2005

The finite volume based multi-block RANS code, WAVIS developed at KRISO, is used to simulate the turbulent flow field around the KRISO container ship (KCS) and the modified KRISO tanker (KVLCC2M). The realizable k-$\varepsilon$ turbulence model with a wall function is employed for the turbulence closure. The free surface flow with and without propeller is mainly investigated for the KCS and the double model flow is concerned for the KVLCC2M which is obliquely towed in still water. The computed results are compared with the experimental data provided by CFD Tokyo Workshop 2005 in terms of wave profiles, hull surface pressure and wake distribution with and without propeller for the HCS and wake distribution and hydrodynamic forces and moments with various drift angles for the KVLCC2M.

• 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.