Serrated Teeth On Blades To Increase The Energy Production Of Wind Turbines

Serrated teeth wind turbine blades
Serrated teeth wind turbine blades. Image: Bernd Zillich – Shutterstock.

Researcher Elena Llorente Trujillo, in her doctoral thesis, has studied how the installation of serrated teeth on the trailing edge of the blades influences the aerodynamic performance of wind turbines. Their results could increase the efficiency of wind turbines.

These devices and their effectiveness in reducing noise have been widely studied, but to date there was no analysis on the effect that these solutions had on the operation of wind turbines.

Elena Llorente Trujillo.

The doctoral thesis has obtained the qualification of outstanding and has been directed by the professor of the Department of Sciences of the Public University of Navarra, Miguel Arana Burgui and by the professor of the Department of Aerodynamics, Wind Energy and Propulsion of the Technical University of Delft, Daniele Ragni.

As the author of the thesis explains, there is a continuous and stable increase in wind power throughout the world, which implies the installation of wind farms in areas closer to urban centers and that the size of the rotors is also very large. larger.

These two factors mean that the noise emitted by the wind turbine can become a reason for complaint if certain levels are exceeded.

Elena Llorente Trujillo.

To avoid this, the industry has proposed different solutions that reduce the level of emitted sound power; among them, the installation of serrated teeth on the trailing edge of the blades.

In his thesis ” Trailing edge serrations effect on the aerodynamic performance of wind turbines ” he has analyzed the impact that serrated teeth have on the aerodynamic behavior of the wind turbine.

First, he performed different theoretical analyzes of the problem and simulations of 2D and 3D airflow geometries around a profile with serrated teeth, a profile with a flat plate and the profile without any device installed. This made it possible to compare and analyze aerodynamic coefficients, speed profiles, turbulence, modification of the wake, etc.

This theoretical study also investigates the impact of the mounting angle of the serrated teeth on the blade and the influence of the thickness of these devices on the aerodynamic behavior of the profile.

Elena Llorente Trujillo.

Satisfactory results

One of the most important results of the theoretical study has been the derivation of an empirical law that predicts the lift coefficient of the profile with serrated teeth from the data of the original profile. To validate this prediction law, an experimental campaign was carried out in the LTT wind tunnel of the Technical University of Delft (Netherlands).

In the experimental results it was observed how the presence of serrated teeth in the profile causes an increase in the lift and resistance coefficients and that these coefficients increase according to the mounting angle.

These data have been compared with the data calculated from the proposed law and a good fit between the two results has been found.

The next step was to use this law to extend the theoretical analysis to the complete wind turbine, with serrated teeth installed on its blades, ” and an increase in both production and loads was confirmed .”

Finally, to validate the theoretical production data, an experimental campaign was carried out in a real wind turbine to which serrated teeth were installed and ” a significantly higher production increase was seen in the real case, compared to that calculated theoretically “. In the same way, an experimental study of the acoustic impact of the aforementioned devices on the noise emitted by the wind turbine was carried out and a reduction in acoustic power above 2dBA was verified.

Via www.unavarra.es

More information: www.sciencedirect.com

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