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CSME 2023/10
Volume 44 No.5
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481-486
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Numerical Study on the Length Parameter of Nabla Type Bulbous Bow of Coastal Tanker
I. Madana and Chang-Ren Chena
aDepartment of Mechanical Engineering, Green Technology Research Center, Kun Shan University, Tainan 710303, Taiwan (R.O.C).
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Abstract:
A numerical study was carried out to predict the effect of different lengths of Nabla type bulbous bow of coastal tanker scaled model. Three different speed values were chosen for this study namely 1.5 m/s, 2 m/s, and 3 m/s which are corresponding to the Froude number of 0.15, 0.2, and 0.3. The original bulbous bow length of 0.9 m corresponds to 8% of the total ship length in the first case, and four more cases of different lengths of 15%, 25%, 50%, and 75% extended bulbous bow of the original length. The results obtained show that the case of a 25% extended bulbous bow is the most effective for all speed values on drag reduction of 10.6 % at 1.5 m/s, 11.6% at 2 m/s, and 27.1% at 3 m/s. the case of 15% is most effective at 3 m/s and achieved a 28.7% on drag reduction. Meanwhile, the case of 75% works as well as the case of 25% for low speed only of 1.5 m/s. The case of 50% doesn’t show promising results, the case of 25% is recommended as it works best for all different speed values.The study found that internal heating regeneration had the lowest specific energy requirement in terms of electrical energy, while compressor air heating regeneration had no electrical energy requirement. However, external heating regeneration had the highest specific energy requirement. The study also concluded that the energy and capital cost for the three modes were comparable at specific conditions of 35°C feed air temperature and 8 bar absolute feed air pressure of product air. The study's findings can be utilized to develop a system comparison tool for practical applications.
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Keywords: Bulbous bow, CFD, Resistance performance.
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©
2023
CSME , ISSN 0257-9731
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