Aerodynamic Analysis of Sail Assisted Ships Using Computational Fluid Dynamics for Improved Sail Geometry and Performance

Abstract

Fossil fuels used for powering ships are major contributors towards marine pollution. Several newlineresearch efforts are in progress to find an alternative efficient powering method to reduce this newlinepollution. This work is an effort towards finding such an alternative where the ship is propelled newlineby an efficient sail propulsion system. Numerical methods are used to arrive at the best sail shape newlineand configuration which would give maximum forward thrust with optimal lateral thrust. For newlinethis, on a candidate ship taken; oil tanker with different number of sails, sail dimensions, and sail newlineforms were analysed by numerical methods, using Computational Fluid Dynamics. The power newlinerequirement of the ship for different speeds up to 12 knots was analysed using the commercial newlinesoftware, Ansys Fluent. The Resistance Vs Speed curve was plotted for this ship. Air flow over newlineNACA 0018 aerofoil section was simulated using Ansys Fluent. The CFD results were verified newlinewith experimental analysis results. The NACA0018 aerofoil sail form was modified newlinesystematically in steps and analysed by two dimensional CFD techniques to find out the form newlinethat performs well for a wide range of wind angle, giving maximum forward thrust. The tip of newlinethe NACA 0018 was modified by tilting it through different angles and at different chord newlinepositions forming a flap for the aerofoil. The flapped aerofoils were formed by modifying the newlineaerofoil at 10% chord length to 60% chord length. The flap angle was also varied from 0 degree newlineto 50 degree in steps of 10 degree. CFD simulations were carried out for all the resulting aerofoil newlineshapes. The forward thrust in the direction of course and the lateral thrust of each of these sail newlinesection were calculated, tabulated and plotted.