Resistance and Propulsion Study of a 17 500-DWT Oil Tanker Using Computational Fluid Dynamics and Slender-Ship Theory: Effects of Energy-Saving Device Fins
摘要
The shipping industry is a major contributor to global carbon dioxide (CO2) emissions, with oil tankers accounting for a significant portion of this contribution. To meet international targets, such as the Energy Efficiency Existing Ship Index (EEXI) and Carbon Intensity Indicator (CII) under the International Convention for the Prevention of Pollution from Ships Annex VI, improvements in hull hydrodynamics and energy-saving technologies are essential. This study investigated the hydrodynamic performance of a 17 500 deadweight ton (DWT) oil tanker equipped with an energy-saving device (ESD) consisting of rectangular flat plate fins optimized at 8° inclination and installed in stern Zones III and IV (forward of the propeller). The novelty of this work lies in its application-specific optimization of flat-plate ESD fins for a midsized tanker, a vessel segment underrepresented in prior ESD studies, and the integration of a comprehensive computational fluid dynamics (CFD) framework validated against the Holtrop–Mennen approach and the slender-ship theory to assess resistance, propulsion, and seakeeping performance, alongside EEXI and CII. Unlike previous studies focusing on container ships or bulk carriers, this research systematically optimized fin geometry and positioning (6 m ahead of the propeller at a tailored inclination angle) for a tanker with high block coefficient (Cb = 0.775) and complex stern flow. The installation of the flat ESD fins achieved a 3.11% reduction in calm-water resistance at service speed, a 2.5% overall resistance decrease in self-propulsion, a 0.24% thrust increase, and 0.08% propeller efficiency improvement, enhancing hull efficiency from 1.213 to 1.344 and propulsive efficiency from 0.776 to 0.848. This resulted in a 2.55% effective horsepower (EHP) reduction and brake horsepower decrease from 3 203.7 to 2 912.4 kW. Consequently, the ship’s EEXI value improved from 9.45 to 8.55 g·CO2/(t·mile), achieving regulatory compliance, while the annual fuel consumption and CO2 emissions were reduced by 8.6%. However, this improvement did not significantly impact the vessel’s operational CII rating, which remained at E. Overall, the study demonstrates that strategically positioned flat fins optimized for tanker-specific flow characteristics with CFD errors below 2% can effectively enhance energy efficiency and reduce emissions, supporting international maritime decarbonization goals while offering a low-cost retrofit solution.