Twenty-Fourth Symposium on Naval Hydrodynamics (2003) / Chapter Skim
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Study on the CFD Application for VLCC Hull-Form Design
Study on the CFD Application for VLCC Hull-Form Design
Pages 98-109
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From page 98... ...
The contents of model tests were resistance and self-propulsion test, wake measurements on a propeller plane, and paint test for visualizing limiting streamlines on a hull. This paper includes the following contents: - Systematic hull-form variation of the stern of slow speed full-ship - Selection of CFD codes - Model tests to predict flow characteristics including resistance and propulsion performance - Calculation of flow characteristics - Evaluation of different stern hull form
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From page 99... ...
is defined to represent the flow patterns Turbulence model around hull as positive in the flow direction, positive y starboard, and positive z upward where the origin is at the bow and undisturbed free surface; while the local coordinate system~x',y',z') to enhance the usefulness of the calculated wake patterns in the propeller design where the origin is at the center of propeller.
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From page 100... ...
The basic hull form is a 309,000 TOW VLCC which was recently designed at HHI. The model tests are carried out to predict the resistance and propulsive performances of ship, and to validate the computational results.
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From page 101... ...
As shown in Figure 2, the breadth of extreme U-form is relatively wide at the Figure 2 Body plan, side profile and sectional area curve of 309,000 TDW VLCC (red: basic form, green: extreme U-form, blue: extreme V-form) Table 2 Hull form characteristics Basic | Extreme l Extreme form U-form V-form LWL.
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From page 102... ...
The changes of hydrodynamic characteristics to be investigated are as follows; - Resistance and propulsion performance - Limiting streamline on the hull - Hull pressure - Wake on propeller plane Resistance and propulsion performance The viscous resistance coefficients(CvM) at Rn=6.916X 106 of three hull forms from the computations and experiments are summarized in Table 4.
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From page 103... ...
The "hook-shape", which is the characteristics of the axial velocity contours, is shown at all three hull forms. Other computational results using COMET, STAR-CD, and FLUENT codes also show same tendencies although their shapes and the lowest values are a little different from each other.
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From page 104... ...
Extreme U-form non non (c) Extreme V-form 0.5 Rt, I 1~'I 1~ , 1` ~ ~ ~ 0 0.02 0.04 0.06 0.08 y -0.04 -n no 1 ', , ', , 1' 0 0.02 0.04 0.06 0.08 y '`\ .,',\,,1,,,,1,, 0 0.02 0.04 0.06 0.08 y Figure 3 Axial velocity contours and velocity vectors at the propeller plane (WAVIS)
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From page 105... ...
Other computational results using WAVIS, STAR-CD, Experiment ._ _ and FLUENT codes also show same tendencies. In the afterward part, the limiting streamlines of three hull forms are quite different from each other.
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From page 106... ...
For the extreme Vform, narrow region of hook shape exists, the value of minimum velocity in this region is relatively low, the radial gradient of the circumferentially averaged axial velocity is steep, and the value of nominal wake is smaller. The characteristics of wake at propeller plane are very much dependent on the turbulence model.
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From page 107... ...
The propulsion performance according to the hull-form variations cannot be evaluated from the computational results only. To apply CFD technology on the development of fuel-economic hull-form at the initial design stage, not only viscous resistance performance but also wave resistance and propulsion performances should be promptly predicted with accuracy.
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From page 108... ...
Min. K.S., Choi, J.E., Yum, D.J., Chung, K.N., Chang, B.J., Chung, S.H., Han, B.W., "Study on the Prediction of Flow Characteristics around a Ship Hull", Proc.
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From page 109... ...
However, the CFD tools have only been used to predict the hydrodynamics characteristics for given hull forms. The next step would be the compiling of CFD tools with optimization techniques, such as gradient-based method, to optimized hull form automatically.
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