Reducing drag with shark model

Fast-swimming sharks have evolved to the point where they are resistant to currents and experience little drag in the water and this has provided the inspiration for a paint which could be used to reduce the aerodynamic drag on planes and ships.

Yvonne Wilke, Dr Volmar Stenzel and Manfred Peschka from the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research have developed a paint that can reduce drag while also reducing the technology required to make it. This will also reduce the fuel consumption– researcher estimate that if every plane were coated in the paint every year, 4.48 million tons of fuel could be saved.

The basis of the paint is nanoparticles; these ensure that the paint withstands UV radiation, temperature changes – which can range from -55 to 70°C – and high speeds. It can be applied as the outmost coating of the plane and adds no additional weight.

“Paint offers more advantages,” said Stenzel, “It can be applied to complex three-dimensional surfaces without a problem.

The paint is not directly applied to a surface – a stencil is used which gives it a sharkskin structure. The unique challenge was to apply the fluid paint evenly in a thin layer on the stencil whilst ensuring that it can be detached from the base, even after UV radiation required for hardening.

The team also hope that it can be applied to ships to help reduce wall friction. They are also working on a solution to the problem of algae of muscles sticking to the ship’s hull.

“One possibility exists in structuring the paint in such a way that fouling organisms cannot get a firm grasp and are simply washed away at high speeds,” said Wilke, “The second option aims at integrating an anti-fouling element – which is incompatible for nature.”

The technology may also be applied to rotor blades of wind turbine. This would improve the efficiency of the system.