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Nature's Lessons to Change Shape of Blades

02 October 2009

Inspired by nature, researches at San Diego State University believe that they can harness the power of wind by using rotor blades that physically adapt to wind conditions in order to make turbines more efficient.

Using composite materials, the team are testing ways of capturing the winds power by building blades that can adjust their shape, rather than fight against the wind. In addition to improved power output, scientists believe that the reduction in stresses on the blades mean that this development could also prolong their life.

Professor Asfaw Beyene, Department of Mechanical Engineering San Diego State University, took inspiration for morphing rotor blades through lessons taught by the animal kingdom. “The idea behind morphing blades was born from the fact that various natural creatures, such as fish, have fins that help them propel through their media at much higher efficiency that man made machines” explains professor Beyene. “The natural flexibility of fins and wings adapts to the swim or fly conditions, maintaining relatively high efficiency at all operating conditions,” Beyene added.

The blades are passive, meaning that they don’t require any external mechanism to induce the change; the blade bends as the wind speed increases and this calculated bend covers the separated boundary layer reintroducing a laminar flow. The study says that this allows the blade to operate at a higher efficiency than rigid blades at part-load.

Researchers believe that this technology could yield a gain of 20-30% kW-hr, as traditional wind turbine blades are designed for a specific wind speed, whereas this system can operate under a varying range of speeds.

Similar shape-changing composite structures are currently being used today in smaller scale applications, such as motorsport spoilers.