Trans RINA, Vol 161, Part A4, Intl J Maritime Eng, Oct-Dec 2019
The results of calculating the frictional resistance and the total resistance of the SALINA model, which are obtained using the ITTC procedures and model tests performed in the towing tank, presented appropriate relationship between the total resistance and the frictional resistance. For example, the ratio of frictional resistance to the total resistance of the SALINA was about 83% in the draft of 16.5 meters (in the laden condition) and in the speed of 0.65m/s (ship speed of 12.5knots), The mentioned result is within the appropriate range as compared to the results of Barrass (2004).
RF RT
= %83 (5)
In the present study, the mentioned ratio varies within the range of 83 to 91% for the Froude numbers of 0.13 to 0.16 (ship speeds of 12.5 to 16.5knots in calm water). To put in a nut shell, the mentioned finding is in line with the results of previous studies.
According to results of uncertainty analysis, carried out for the experimental model, at speeds of 0.65, 0.70, 0.75, 0.80 & 0.85m/s, the maximum uncertainty of the measured resistance in 8 and 16.5cm. drafts were found 0.89% & 0.77%, respectively.
4. CONCLUSION
Approximately 90% of the resistance of all tankers is related to their frictional resistance and about 10% is related to their wave resistance. In ships in which the hull surface area outside the water is greater, such as passenger and container ships, frictional resistance is about 30 to 40%. Furthermore, wave resistance is one of the main factors affecting the variations in fuel consumption patterns of these ships. In this applied research, using a powerful computational fluid dynamics software (i.e., ANSYS CFX software) a numerical simulation of SALINA belonging to the National Iranian Tanker Company was presented. The mentioned model was used to calculate the drag force values of the ship’s hull with consideration of the highest frequency of the actual service conditions over the last 4 years in the laden & ballast conditions (drafts of 8 and 16.5m) and at speeds of 12.5 to 16.5knots. In order to validate the obtained findings, the results of the numerical modeling were compared with the test results of the experimental model of SALINA performed in the towing tank. Based on the validations carried out, the difference between the results of the experimental and numerical models at low speeds was about 7% and at higher Froude numbers was observed to be up to 15%. Consideration of the difference in the calculated results presented in other studies, which varied from 5 to 17%, reveals that the computational error of the results obtained from this study is evaluated in an appropriate range.
3. 5. ACKNOWLEDGMENTS
The authors of the present article appreciate the valuable support of the technical & ship management director of the National Iranian Tanker Company, Mr. Akbar Jabal Ameli. Furthermore, a special gratitude is expressed to Dr. Hadi Mirzaei, Mr. Anooshirvan Yousefi Darestani, Dr. Shahriar Abtahi, and SALINA superintendent, Mr. Kambiz Moradi, who provided remarkable insights and contributions. Moreover, it is necessary to appreciate the detailed plans of the SALINA masters, including the late captain Majid Ghasabi Oruji and duty officers of the bridge and engine room of SALINA, who recorded and provided the key information needed during the voyage. We also sincerely appreciate Mr. Amir Mostashfi for his endless effort and effective and worthwhile support. His guidance increased the accuracy of the study and facilitated the implementation of the experimental tests of the model.
6. 1.
REFERENCES
PARK, B J., SHIN, M-S., KI, M-S., LEE, G J., LEE, S B. Experience in Applying ISO19030 to Field Data. 2nd Hull Performance & Insight Conference. HullPIC’17. Ulrichshusen. 2017. March 27-29.p.150-155.
2.
ZALEK, H. S. F., BECK, R. F., CECCIO, S. L. “High Speed Model Testing With Drag Reduction”, University of Michigan, 2004.
VAN, S. H., KIM W. J., KIM, D. H., YIM, G. T., LEE, C. J., and EOM, J. Y., 1998. Flow measurement around a 300K VLCC model. Proceedings of the annual spring meeting, Ulsan, pp.185-188.
4. 5.
OGIWARA, S. and KAJITANI, H., 1994. Pressure distribution on the hull surface of series 60 model. Proceedings of CFD Workshop Tokyo, pp.350-358.
JONES, D. A., CLARKE, D. B., 2010. Fluent code simulation of flow around a naval hull, the DTMB 5415. Technical report, Defense Science and Technology Organization. DSTO-TR-2465, 30P.
6.
OBREJA, D., POPESCUE, G, IONAS, O. and PACURARU, F.,
7. 8. 2005. Experimental
techniques for vortices investigation around the ship model, Workshop on Vortex Dominated Flows, Romania.
KORKUT and USTA., “Reduction of Ship Resistance through Induced Turbulent Boundary Layers”, Master of Science in Ocean Engineering, Melbourne, Florida, 2010.
LUNGU, A., “Numerical Simulation of the Free-Surface Turbulent Flow around a VLCC Ship Hull”, AIP Conference Proceedings 936, Corfu, Greece, 16-20 September 2007, p.647- 650.
©2019: The Royal Institution of Naval Architects
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