Scientists have found a way to reduce the aerodynamic drag of sailing ships. Chalmers University of Technology reports.
Environmentalists estimate that carbon emissions from shipping must be halved by 2050 to meet the Paris Agreement’s climate goals. One way is to convert some ships into sailboats – although modern turbosails don’t look like historic canvas sails and look like vertical tubes that can be powered by an internal combustion engine. However, a major problem with turbo sailing ships is their own aerodynamic drag, which prevents the ship from accelerating.
Swedish scientists have introduced a new method that partially eliminates this shortcoming. Inspired by the aerodynamic principles used in aviation, the researchers found a way to reduce a ship’s aerodynamic drag by 7.5%. The result is increased energy efficiency and reduced fuel consumption (with hybrid operation).
The most important part of this method is the Coanda bonding effect. This is based on the tendency of the liquid (and air) to flow rather than be pushed by a convex surface. In shipping, one of the main sources of aerodynamic drag is the square-shaped aft of a ship’s superstructure protruding from the deck. The new method invokes the Coanda effect around this area.
The Coanda effect balances the air pressure on the ship’s hull by creating a convex-sided structure in the ship’s superstructure and allowing high-pressure air to flow through the ‘jet slots’. This significantly reduces aerodynamic drag, making the vehicle more energy efficient.
For an oil tanker from Saudi Arabia to Japan, this would mean a reduction in fuel consumption of about ten metric tons.