Thursday, December 24, 2009

GE Creates Superhydrophobic Nano-Coatings to Prevent Icing on Wind Turbines and Jet Aircraft

 Joseph Vinciquerra, a project leader in the Mechanical Integration & Operability Laboratory at GE’s Global Research Center in Niskayuna, New York,  and his team have for the past several years been working with nanotechnology to understand and exploit superhydrophobic materials in an attempt to make surfaces resistant to atmospheric icing, or ice that forms at certain altitudes or on the ground in cold weather climates.

By superhydrophobic,  GE means creating materials that are super water repellent. It’s similar to “nano pants” that are spill or stain resistant. It’s amazing… you can spill coffee or juice and the liquid just rolls off the clothing without causing a stain. At GE interests are much different. GE products like wind turbines and aircraft engines come into contact with water all the time, often in the form of ice.

For a wind blade that’s 200 feet up in the air, ice buildup can cause significant drag on the blade and reduce the turbine’s energy production. For aircraft engines flying at 30,000 feet, engineering solutions are used to prevent icing, but they typically cost significant engine efficiency. But what if we could place special nano-coatings on a wind blade or on aircraft engine parts that could repel water? And what if these coatings also could repel ice? If we could eliminate the need for expensive, energy intensive systems to prevent icing, we could realize a big improvement in efficiency. In the case of the wind turbines, for example, this would enable much higher energy production says Vinciquerra.

What GE has essentially done is re-create how atmospheric icing occurs in a lab environment to test its superhydrophobic materials.  GE created a test facility that simulates these specific conditions within novel wind tunnels, which allow them to conduct experiments on new materials in the icing conditions of interest. GE also has numerous facilities and test methods that allow us to simulate a vast array of harsh environments – like high-speed sand erosion and artificial UV exposure – to make sure the materials they’re developing are robust enough for the real world. With these tools at its disposal, and a multi-faceted team of chemists, material scientists, aerospace and mechanical engineers (to name a few), GE has made substantial progress toward new coatings that not only dramatically reduce the adhesion strength of atmospherically-formed ice, but also hold up to rigors of real-world operating conditions.

In the video shown here, GE shows two generic airfoils side-by-side in one of its icing wind tunnels. The specimen on the left-hand side is made of titanium, and the specimen on the right-hand side is made of aluminum coated with a thin layer of one of our coatings. At the start of the video, you can see ice forming on the upper-most edge of both specimens as the air flows over each airfoil from the top of the screen toward the bottom. As the ice accumulates, you’ll see both airfoils rotating toward you as the air is allowed to act against the ice that has formed. As you can see, our coating technology greatly affects the way ice tries to adhere to the surface!

In this example, GE relies on the aerodynamic forces of the wind acting against the ice to release the ice from the structure. Thus, we have developed a true “de-icing” material that does not require any additional power or heat from the system. While this already offers exciting possibilities for some of the world’s toughest icing challenges, our team continues to refine these materials for a multitude of potential applications, while also working to create new “anti-icing” surfaces (those where ice does not form at all!) based on similar principles.

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