Wingsail layout design and shape optimization using a CFD-aided Taguchi approach: The Aegean Marathon case study

Abstract

The use of wind-assisted propulsion devices is a proven engineering technique to reduce the fuel oil consumption and the emitted pollutant gases. Such a device, mainly employed for naval applications, is the wingsail. The present work aims at developing a realistic wingsail configuration with respect to vessel limitations, defining some key optimization guidelines and design trends, and proposing a methodology based on high-fidelity, computational modeling. The Suezmax tanker Aegean Marathon, owned and operated by Arcadia Shipmanagement Co Ltd, serves as a reference platform. The design space is defined and efficiently investigated by utilizing a Design of Experiments (DOE) approach. By employing the Taguchi method, nine (9) wingsail configurations are drawn, with the aspect ratio, taper ratio and number of pairs serving as the key design parameters. The characteristics and constraints of the vessel are also considered, emphasizing on the deck areas that are available for installation. The aerodynamic characteristics of each configuration are analyzed with Computational Fluid Dynamics (CFD) and the interactions between the sails are evaluated. The thrust and sway force coefficients, the yaw and roll moments coefficients and the weight of each configuration are defined as the main performance criteria. An Analysis of Variance (ANOVA) is conducted to determine the contribution of the design parameters to these criteria. The optimal combination is determined and its impact on the vessel's performance is assessed. The actual benefit of the optimal wingsail configuration is computed according to wind data obtained from an Aegean Marathon's route and the appropriate conclusions are drawn. Indicatively, as derived by the results of this work, ignoring the interactions between the wingsails can falsely lead to a significant overestimation of their overall performance. Moreover, it is shown that the realistic vessel-related constraints and limitations have a considerable impact on the design space of the wingsails configuration and, as such, should not be excluded. Even though the above limiting factors are considered in this work, the results still indicate that a significant, double-digit, reduction can be achieved in terms of fuel consumption.