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Silent rotors by acoustic optimisation (SIROCCO)


Objectives and problems to be solved:
Despite the fast acceleration of wind energy implementation, wind turbine noise is still one of the major obstacles for the widespread use of wind energy in Europe. For modern large turbines, aerodynamic (in particular trailing edge) noise is considered to be the dominant noise source. The principal objective of the present project is to develop airfoils and possible other concepts, by which the aerodynamic noise of full-scale wind turbine blades can be reduced considerably (say 3-6 dB), without a reduction in power performance. The airfoils will be designed using a new combined acoustic-aerodynamic design methodology. This methodology is based on the method from the previous EU-project 'DATA' to design acoustic blades for a wind tunnel model rotor. In the present project the method will be extended for the full-scale situation. The performance of the turbines will be validated using a new measurement technique, which can localise and quantify noise sources on a rotating blade.
Description of the work:
The project will be carried out by a balanced consortium, which brings together the major European experience and knowledge in the required fields. The consortium consists of a major blade and leading wind turbine manufacturer, a wind energy consultancy company, and Europe's leading research institutes in the field of wind turbine acoustics and aerodynamics.
The project is aimed at two different (reference) turbines, for which acoustically optimised blades will be designed, manufactured and validated in field tests. Both reference turbines are pitch controlled and have a diameter of about 60 m. The activities performed in SIROCCO can be roughly divided in the following phases. In the first phase, acoustic field measurements are carried out to characterise the noise sources on both baseline turbines. Using the acoustic array measurement technique, it will be verified whether indeed trailing edge noise is the dominant noise source. (Milestone 1). If other noise sources are present (e.g. gear box, tip noise, holes/slits), it will be attempted to reduce or eliminate these noise sources. In the second phase, a combined acoustic/aerodynamic design methodology will be utilised to design acoustically optimised airfoils. The new airfoils should be compatible to the inner blades of the baseline turbines, while maintaining the aerodynamic requirements. The optimised airfoils are tested in two-dimensional aerodynamic and acoustic wind tunnel tests and compared to the reference airfoils, for varying conditions (Milestone 2). In the third phase the design of full-scale rotor blades with the new airfoils will be performed. Using analytical tools, it will be assessed how promising the new designs will be (Milestone 3). In the fourth phase the full-scale optimised blades will be manufactured, after which their acoustic and aerodynamic performance with respect to the baseline blades is verified in detailed field measurements for varying conditions. On the basis of the experimental results a final evaluation and assessment of the business potential of the new blades will be performed for both turbines.
Expected results:
The final result of SIROCCO is a set of validated full-scale, low-noise rotor blades for both reference turbines, with the same power performance as the existing blades. This final result will be accomplished through a number of intermediate results, such as a validated design methodology for low-noise airfoils, and a proven acoustic measurement technique for location and quantification of rotating noise sources.

Funding Scheme

CSC - Cost-sharing contracts



Participants (5)

Bedrijvenpark Twente, 301
7602 KL Almelo
Poligono Industrial Los Agustinos S/n
31003 Pamplona
Kohnsteinbruecke 10
99734 Nordhausen
Anthony Fokkerweg 2, 1059 Cm Amsterdam
1006 BM Amsterdam
21,Pfaffenwaldring 21
70585 Stuttgart