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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Society of Naval Architects of Korea
Journal Basic Information
Journal DOI :
The Society of Naval Architects of Korea
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Volume & Issues
Volume 34, Issue 4 - Nov 1997
Volume 34, Issue 3 - Aug 1997
Volume 34, Issue 2 - May 1997
Volume 34, Issue 1 - Feb 1997
Selecting the target year
Development of Two Dimensional Blade Section with High Efficiency for Marine Propeller
Na, Yun-Cheol ; Song, In-Haeng ; Ahn, Jong-Woo ;
Journal of the Society of Naval Architects of Korea, volume 34, issue 1, 1997, Pages 11~23
This paper contains a new approach to blade section design method for marine propellers. The hydrodynamic characteristics of 2-D section are highly influenced by its geometrical parameters i.e., thickness and camber distributions and leading edge radius etc. To consider fully turbulent flow field near 2-D section. the finite volume method with k-
turbulent model which solve Reynolds time averaged Navier-Stokes(RANS) equation is applied. In this study, O-type grid system that can provide many calculation points on blade surface is used. The results were compared with those of the experiment of NACA0012 to confirm the accuracy of the developed codes. The goal of this study is the development of a blade section with high efficiency and low drag. To achieve this, we carried out the tests of lift, drag and cavitation characteristics in cavitation tunnel. The results of experiment were compared with numerical results in order to validate the proposed blades design method. By comparing the numerical results with the experiments, we found that the new blade section, KH28 allows superior performance in efficiency and cavitation avoidance characteristics. We further investigated the blade section design method and an application study of this section, KH28 to apply to the marine propeller. In order to improve the accuracy of numerical results on prediction of lift and drag, we conclude here that the 2-layer boundary model must be used.
Effects of the Fillet Forms on the Juncture Flow
Kim, Sun-Young ;
Journal of the Society of Naval Architects of Korea, volume 34, issue 1, 1997, Pages 24~40
Horseshoe vortices generated around the juncture between the ship and her appendages often lower a performance of the ship by increasing the appendage drag and making a non-uniform wake on the propeller plane. This paper investigates numerically how the fillet around the juncture of the leading edge influences the juncture flow and the appendage drag. Computation has been made by solving Navier-Stokes equations with MAC method and the flows are at the Reynolds number of 5,000. Five fillets with different height-breath ratios and curvatures are chosen as test models to find out the effects of the shape of fillets on the appendage drag and wake. Computational results show that fillets with a smaller height-breath ratio and/or with a concave curvature has smaller appendage drag and more uniform wake.
A Study on the Propeller Thrust for a Moored Ship
Ha, M.K. ; Song, I.H. ; Kim, D.J. ; Wee, K.S. ; Kim, S.W. ;
Journal of the Society of Naval Architects of Korea, volume 34, issue 1, 1997, Pages 50~59
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.
A Rate-Dependent Elastic Plastic Constitutive Equation in Finite Deformation Based on a Slip Model
Nam, Yong-Yun ; Kim, Sa-Soo ; Lee, Sang-Gab ;
Journal of the Society of Naval Architects of Korea, volume 34, issue 1, 1997, Pages 77~86
The advanced development in many fields of engineering and science has caused much interests and demands for crashworthiness and non-linear dynamic transient analysis of structure response. Crash and impact problems have a dominant characteristic of large deformation with material plasticity for short time scales. The structural material shows strain rate-dependent behaviors in those cases. Conventional rate-independent constitutive equations used in the general purposed finite analysis programs are inadequate for dynamic finite strain problems. In this paper, a rate-dependent constitutive equation for elastic-plastic material is developed. The plastic stretch rate is modeled based on slip model with dislocation velocity and its density so that there is neither yielding condition, nor loading conditions. Non-linear hardening rule is also introduced for finite strain. Material constants of present constitutive equation are determined by experimental data of mild steel, and the constitutive equation is applied to uniaxile tension loading.
Hybrid Optimization Algorithm based on the Interface of a Sequential Linear Approximation Method and a Genetic Algorithm
Lee, Kyung-Ho ; Lee, Kyu-Yeul ;
Journal of the Society of Naval Architects of Korea, volume 34, issue 1, 1997, Pages 93~101
Generally the traditional optimization methods have possibilities not only to give a different optimum value according to their starting point, but also to get to local optima. On the other hand, Genetic Algorithm (GA) has an ability of robust global search. In this paper, a new optimization method - the combination of traditional optimization method and genetic algorithm - is presented so as to overcome the above disadvantage of traditional methods. In order to increase the efficiency of the hybrid optimization method, a knowledge-based reasoning is adopted in the part of mathematical modeling, algorithm selection, and process control. The validation of the developed knowledge-based hybrid optimization method was examined and verified applying the method to nonlinear mathematical models.
A Study on the Interactive Grain Stability Calculation
Lee, S.S. ; Lee, K.O. ; Kang, W.S. ; Yoon, M.T. ; Sung, D.K. ; Lee, J.C. ;
Journal of the Society of Naval Architects of Korea, volume 34, issue 1, 1997, Pages 102~110
In a shipyard, computer calculation is not frequently used for the grain stability calculation because of large difference between calculation values and real values. Therefore, the necessary calculation process for grain stability is done manually. GUI(Graphical User Interface) is adopted for the convenience of users and interactive data I/O. The hold shape (girder, hold, etc.)needed for calculation are visualized using GLBAX which is a 3 dimensional graphic library. The interface with the ship basic calculation package is also implemented. The aim of this paper is to develop a reliable interactive grain stability calculation program which reduces computational time, and is to computerize the grain stability calculation procedure.