quiet round

The study of the silent breath of respiration (the owl series) led to the development of an innovative coating for the blades of wind turbines, which significantly reduces the noise they produce

By: Yael Halfman Cohen

Breathing is known in the quiet world, and was even used in the past as a source of inspiration and knowledge for a solution The noise problem on the Japanese train. Recently, a new study was published, which deals with possible applications of the noise reduction mechanism in wind turbines and airplanes.

Researchers at the University of Cambridge, in collaboration with colleagues from several institutions in the USA, presented this month, at the annual conference of the American Institute of Aeronautics and Astronautics in the USA,
American Institute of Aeronautics and Astronautics (AIAA), a biomimetic noise-reducing surface, following research on the quietness of breathing.

Many birds, especially the larger ones, manage to fly quietly during the hunt. This phenomenon has been known for many years, but what was not known was how they do it. We have already reported on the research group from Cambridge, which in recent years has studied the silent flight of breathing. This research has recently matured into the development of a prototype coating for the blades of wind turbines, which can significantly reduce their noise.

Inhalants have three known structures that contribute to quiet flight: (1) a comb of stiff feathers along the edge of the wing, (2) downy material above the wing, and (3) flexible fringes (fringes) on the side of the wing. Using high-resolution microscopy, the researchers were able to examine the structure of breathing feathers with a high level of precision. They noticed that the flight feathers have a downy covering, very reminiscent of the appearance of a forest top from above. In addition to the light "top", at the leading edge of a breather wing there is also a flexible comb made up of equally spaced bristles, and a flexible and perforated edge at the trailing edge. No other bird seems to have such a sophisticated wing structure. Most of the noise generated by the wing originates at the trailing edge, where the air is swirling as it passes over the wing. The unique structure of the breathing wing allows the air to pass smoothly and diffuses the sound created so that the prey cannot hear the breathing.

The researchers developed a coating that could split the sound generated on the turbine blade in a similar way. The coating prototype was 10D printed from plastic, and was used to coat a full-size turbine blade. The coated blade was placed in a wind tunnel and a reduction of the noise by XNUMX decibels (significant) was demonstrated, without affecting the aerodynamic properties of the blade. As a result, it will be possible to limit the rotation speed of the turbines less, they will be able to spin faster and produce more energy, with less noise. For wind turbines of average size, this is a significant increase in electricity output.

It seems that this coating, which imitates the sophisticated structure of breathing feathers, can indeed significantly reduce the noise created by the operation of blades found in turbines, computer fans and even airplanes. The next stages of the research will deal with the optimization of the coating, its examination on a turbine in the field (rather than the laboratory), and its adaptation to additional applications.
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