Low-Noise Coating for Wind Turbines Inspired by Shark Skin

Innovation: Industry

Riblet4Wind

Image: Gerald Schömbs / Unsplash / CC BY SA - Creative Commons Attribution + ShareAlike

Move in/Through Gases

Living systems must move through gases (which are less dense than liquids and solids) such as those in the earth’s atmosphere. The greatest challenge of moving in gases is that because the living system is heavier than the gas, it must overcome the force of gravity. Moving efficiently in this light medium presents unique challenges and opportunities for living systems. As a result, they have evolved countless solutions to optimize drag and increase lift so that they can stay aloft and take advantage of variable currents. Additionally, they must overcome gravity when moving from a liquid or solid into the air. The fairyfly, the smallest known insect, is a tiny wasp that must move through the air. To the wasp, air feels like a heavy liquid and to move through it, it uses special feathery oars rather than wings.

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Manage Turbulence

A turbulent force occurs when air or water creates a chaotic or irregular motion. The source can be such things as wind, waves, and eddies caused by obstructions to air or water flow (such as that created by a rock in a stream). Because the force is irregular, it acts in unpredictable ways on multiple parts of a living system at any given time, decreasing the living system’s efficiency. Strategies used to manage turbulence include dampening the amount of turbulence, having flexibility to handle sudden changes, and making quick adjustments. An example is the mucus on aquatic organisms, such as barracuda sharks, that can reduce turbulent friction of seawater by 66%. In doing so, it decreases drag and increases the sharks’ swimming efficiency.

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Riblet Coating from Riblet4Wind is a surface coating that creates a textured surface to reduce turbulence and noise while increasing power in wind turbines.

Benefits

Reduced turbine noise
Reduced turbulence
Increased power

Applications

Wind turbine blades
Fans, airfoils, and other similar equipment
Renewable energy

UN Sustainable Development Goals Addressed

Goal 7: Affordable & Clean Energy

The Challenge

When air moves, it generates sound. The more movement, the greater the sound. Onshore wind farms can create a lot of noise, but must comply with local noise regulations. As a result, many onshore wind turbines have to run at reduced power, resulting in less energy, in order to keep noise levels down.

Innovation Details

Riblet Coating is a surface coating that is applied to wind turbine blades. The small riblets in the coating mimic shark denticles, which help to reduce drag and increase lift. This allows the wind turbine to operate with the same effectiveness at lower wind speeds, while also reducing noise.

Biological Model

Some species of sharks can swim at impressive speeds of 50 km/h (31 mph). Their skin is covered in small bony scales called dermal denticles. It has long been hypothesized that shark scales reduce drag by managing the water flow closest to the skin. In addition, shark denticles may help vortices (low-pressure regions of swirling water) stay attached to particular areas of the shark’s body, resulting in more suction and forward thrust. Thus, a shark’s denticles may increase swimming speeds by increasing thrust in addition to reducing drag.

See Related Strategy

Biological Strategy

Scales Manipulate Flow

Sharks

Scales on sharks influence drag and thrust during swimming by manipulating fluid flow next to the body.

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