• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.825-834
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• 2008

Nose chine shape optimization study has been performed to maximize the directional stability at high angle of attack supersonic flow. Various chine shapes are generated using super ellipse equation. By numerically investigating the directional stability characteristics of those shapes, the baseline configuration for the shape optimization has been selected using the three-dimensional Navier-Stokes equations. The configuration is represented by the NURBS curves which can adjust the surface geometry by the control points. The response surfaces are constructed to obtain optimum shape which has high directional stability characteristics and lift-to-drag ratio. From this study, an efficient configuration design and optimization process which utilizes the parameter-based configuration generation techniques and approximation method has been established, then 29% improvement of the directional stability by strong vortexes from chine nose is accomplished.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.3
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• pp.273-285
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• 1996

Generally, the flow around the ship's hull often appear 3-dimensional separation at the bow and stem, and the vortex by this flow affects greatly the resistance propulsive efficiency and maneuverability of the ship. This study is compared the calculated result based on the streamlines calculation method with the experimental result by oil fIlm method to analyze the patterns and characteristics of the flows around the ship's hull of chine form. DTMB Series 62, 4667-1 vessel was selected as a sample ship of chine form and model ship was painted with the mixture of oil-color, paint, and poly wax at the surface of the vessel and tested in the model towing tank of Inha University. The results obtained in this study are listed briefly as follows ; 1. For the single chine form, after $4\frac{1}{2}$ station the streamlines are crossed at the chine line and the streamlines are converted to the vortex follow the chine line. 2. For the single chine form, the vortex appered increases and severely in and arround the stern. 3. The approximate streamlines for the ship's hull of chine form can be assigned by the use of the Watanabe's basic transformation formular.

• Bulletin of the Society of Naval Architects of Korea
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• v.10 no.1
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• pp.33-44
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• 1973

Chine형 선체단면 주상체의 자유표면에서의 상하운동에 수반되는 부가질량과 감쇠력을 Ursell-Tasai 방법에 의하여 계산하였다. Chine형에서 구하여진 결과는 같은 선체단면적 계수와 반폭흘수비를 갖는 등가 Lewis형의 결과와 비교하였고 선체단면의 형상이 부가질량 및 감쇠력에 미치는 영향을 고찰하였다. Chine형과 등가 Lewis형 선체단면 주상체에 파고가 일정한 횡파가 입사할 때의 상하운동을 고찰하였다. 이상과 같은 계산 및 고찰을 통하여 다음 결과를 얻었다. 1) 자유표면이 부가질량에 미치는 영향은 chine형이 등가 Lewis형단면보다 큰 값을 갖는다. 2) 선체단면적계수와 반폭흘수비가 같은 경우에 감쇠력의 크기는 Lewis form, single chine, double chine순서이다. 3) 선체단면계수와 반폭흘수비는 상하운동에 가장 큰 영향을 미치는 것으로 생각되며, 선체단면의 기하학적인 변형이 운동에 미치는 영향은 중요한 요소가 되질 못한다. 4) 감쇠력계수와 선체단면계수와의 관계는 간단한 관계를 유지한다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.5
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• pp.566-573
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• 2017

The chine of high speed vessels does not only play a role in changing position when planing but also helps balancing the hull. It also has a great influence on resistance performance. However, designing a chine requires a lot of experience because it is influenced by various factors such as displacement, transom shape, draft and width. Such a design is not based on an empirical formula, but the purpose of this study is to provide basic guidelines regarding the shape of chine through calculation. This design was developed using Yacht-one, a commercial design program, and analysis was performed using Star-CCM+, also a commercial analysis program. Analysis of the hull selected in this study was carried out by Dynamic Fluid Body Interaction (DFBI) method. Analysis of the chine was carried out at chine angles of 15, 16, 17, and 19degrees, at a speed of 30knots. The result indicated that the highest trim occurred at 16 degrees among the four chine angles considered, and the highest heave occurred at 15degree. In terms of resistance performance, minimum resistance was observed at 16 degrees. Consequently, for minimum ship resistance, it is necessary to complete calculations in accordance with the chine angles, ${\pm}2$ degrees from the initial chine angle, which should be carried out a the design stage.

• Bulletin of the Society of Naval Architects of Korea
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• v.9 no.1
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• pp.1-6
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• 1972

To contribute towards more accurate estimation of the virtual coefficient for the vertical vibration of the chine-type ship, experimentally obtained three-dimensional correction factors, J, of added mass of prismatic beams having cross section shape of hypotrocoid characters, slightly concaved Lewis form and elliptic form are investigated in connection with the applicability of an approximate analytical calculation method compared to that proposed by T. Kumai[6] for the Lewis form cylinders, and synthetically in compared with the experimental works on various cross section shapes of the other type by L.C. Burril et al[8] and the analytical works on the ellipsoid of revolution by F.M. Lewis[1] and J.L. Taylor[2]. The experimental results show that the aforementioned analytical method gives, unlike that for the Lewis form cylinders, considerably larger J-values for the chine-type cylinders, and that the influence of the character of the cross section shape on J-values is not remarkable in practical sense. Finally, considering in synthesis the experimental results on prismatic beams, the Burril's works on palabolic plan form and elliptic plan form, and that the chine-type ship usually has a hull form of transom stern, it is fairly safe to say, at the present stage, that adoptation of the Taylor's J-values will not results in any large error in estimation of the virtual inertia coefficients of the chine-type ships.

• Bulletin of the Society of Naval Architects of Korea
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• v.5 no.2
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• pp.45-50
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• 1968

The added mass and the added moment of inertia of a hard chine hull for heave and pitch were calculated by strip method. For the $k_2$ coefficients, Hwang's values for the straight-framed sections were used and for $k_2$ coefficients Porter's values for ellipses were used in the calculation. Comparisons on added mass and added moment of inertia of hard chine hull with those of ordinary hull form were briefly discussed. The results of the calculation for hard Chine hull give greater valves than ordinary ships at zero Froude Number. Beam draft ratio seems to be much influenced on the added mass and added moment of inertia.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.2
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• pp.92-97
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• 2006

Hull forms of a high speed small boat have been developed through numerical studies. A round bilge type hull form has been drived form a using chine hull form with HCAD, a hull form variation software. Wave resistance and the flow fields around the ships have been computed using well-known software, WAVIS. This software employs Rankine source method with non-linear tree surface condition as well as dry transom boundary conditions. The round bilge hull form showed better resistance performance than to the chine hull form for the whole speed range. However, considering the building and labor costs of the small shipyard, the chine hull form has been selected and its wave resistance characteristics has been improved by modifying the bow regions and applying the stem wedge. It is found that the effect of stem wedge is quite satisfactory to improve the resistance characteristics of high speed chine hull form.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.4
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• pp.341-349
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• 1994

From the results of model tests, statistical regression analysis for EHP estimation based on hull form parameters is adopted in this study. From this result, the method for estimation of EHP and optimization of hull form parameters at the initial design stage of fishing boats is developed. This method is applied to two standard fishing boats with chine lines. The EHP s are estimated and compared to experimental results. From the optimization of four principal hull form parameters of these fishing boats, approximately 19% of resistance reduction at the design speed is achieved and thus certifies that this method can be used efficiently for the initial design of hull forms of fishing boats.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.89-93
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• 2002

Resistance performance of 6.67 G/T class fishing vessel is experimentally investigated in low and middle speed ranges to find out the effect of a new chine. The tests are performed for four different cases in the circulating water channel(CWC). Wave patterns are observed together to make clear the relation between the resistance performance and the wave characteristics. The results show that the new chine can be one of the effective device to reduce the resistance.

• Bulletin of the Society of Naval Architects of Korea
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• v.11 no.1
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• pp.1-8
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• 1974

Hydrodynamic forces and moments produced by the swaying oscillation on the free surface were exactly calculated by Ursell-Tasai method for the cylinders with Kim's chine form sections and the sway responses of the cylinders of those chine form sections among the regular beam sea were also calculated. The results of the computation were compared with those of Lewis form sections. It is concluded that the effects of the section form on the added mass, and damping are small, if the section forms had same beam-draft ratio and sectional area coefficient in the case of sway motion. It is also known that the above little effects of section shapes on the basic hydrodynamic forces do not effect on the sway motion responses of cylinderical bodies among the regular beam sea. The sway motion responses of cylinderical bodies are varied linearly with the wave numbers.