2020-07-03
http://w3.windfair.net/wind-energy/pr/7027-new-solution-against-erosion-and-icing-on-leading-edges

News Release from Hodij Coatings BV

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Wind Industry Profile of


New solution against Erosion and icing on leading edges.

Erosion on rotor blades is not just a wind turbine related issue. Several industries are affected by this phenomenon. For example the rotor blades on helicopters. Rotating with much higher velocity, the protection of the leading edges here is even more important. The air intake on the jet-engines of commercial airliners, where wind speeds can reach from 800 KM/H up to 1200 KM/H, are also very much affected by erosion, even on the hard steel substrate. Icing is another distortion of aerodynamic behaviour on rotor blades and airplane wings. At high altitudes icing is more common then exception.
Not all water freezes at 0°C or 32°F. Liquid water below this temperature is called super cooled and such super cooled droplets cause the icing problems on aircrafts and wind turbine blades. Below -20°C, icing is rare because clouds at these temperatures usually consist of ice particles rather than super cooled water droplets. Below -40oC it is generally accepted that icing on aircraft is negligible.
The most costly influence of erosion and icing on WTG rotor blades, is the fact that the aerodynamic wind flow is interrupted and the optimum performance will decrease. Severe leading edge erosion is most often not discovered until inspections are performed, not knowing for how long this has affected the machine performance. For the repair of leading edges corrupted by erosion, even higher costs are necessary. Downtime, crane- or scaffold rent, repair time are some of the issues that come next. If the aviation industry can prevent these costly repair intervals, so should this be applicable on the rotor blades of wind turbines.

The challenge was to generate a product that will not tolerate ice, debris, sand and other air born particles to its surface. Secondly, this product needed to be highly impact resistant, hard yet flexible, extremely durable and easy to apply and (if necessary) easy to repair. The most commonly used leading edge protection is a so called; anti-fouling foil. Highly resistant, but not durable enough and labour intensive to apply and repair. If not applied correctly (not uncommon),air-bubbles will require repair within 24 months. The answer to this problem comes from the Aerospace industry. Instead of following the anti-fouling foil concept, a innovative new coating with the requested characteristics was tested. Not just by anyone, but by the British Ministry of Defence. After months of testing this coating under the severest conditions, this coating is now applied on rotor blades of the British Apache helicopters. After Boeing performed extensive test (Rain erosion test, with high speed water drops on leading edges) the yet-engines air intake are now protected by the same coating.


What kind of coating are we talking about?

You all now the characteristics of Teflon on the bottom of frying pans at your home. This became the answer to most of the requested specifications. Due to specific alterations and modifications this Teflon based coating will not tolerate any foreign substance on its surface. Not water, dust or any other material. Durability is approximately 7 times longer then any existing anti-fouling foil. In a sandblasting-test where this Erosion Resistant Coating and Anti-Fouling where sandblasted with a sharp grain, the coating lasted 7 times longer then the foil. Due to the cohesive character of a sprayed on coating, air-bubble are no issue. The application of this coating is easier then the anti-fouling foil, because it is sprayed on the leading edge. Resulting in a bubble free cohesive hard surface, yet flexible to go with the shape of the rotor blade, similar like on a aircraft wing.
This coating can also be applied on blades already performing in the field.
Source:
Hodij Coatings BV
Author:
Carmen Hoogeveen
Email:
carmen@hodijcoatings.nl
Link:
www.hodijcoatings.nl/...



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