Aerodynamic noise reduction for variable speed HAWTs

Informazioni relative al progetto

ID dell’accordo di sovvenzione: JOR3950045

Progetto chiuso

Data di avvio 1 Gennaio 1996

Data di completamento 30 Aprile 1998

Finanziato da

• Specific programme for research and technological development, including demonstration in the field of non-nuclear energy, 1994-1998

Costo totale

Nessun dato

Contributo UE

Nessun dato

Coordinato da

RENEWABLE ENERGY SYSTEMS LTD.
United Kingdom

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Risultati sfruttabili

Aerodynamic noise reduction for variable speed turbines

The aim of this project was to undertake a thorough investigation of blade design for variable speed wind turbines with specific emphasis being on techniques to reduce aerodynamic noise emission from the rotor. The main tasks of the project were: to perform comprehensive noise measurements on a variable speed wind turbine; to optimize blade geometry and specify the required aerofoil characteristics for a low noise blade; to develop aerofoil and blade designs to achieve the required aerodynamic noise and performance characteristics. The measurements were correlated with tip speed, angle of attack, and 50m wind speed, using the method of partial residuals. The results showed that the dependence of noise on tip speed varies with the frequency of the noise, lower frequency noise (< 400 Hz) generally being less sensitive to tip speed. Correlations of residuals with angle of attack showed no clear pattern despite the wide range of angle of attack residuals (-5 to +2 degrees). Similarly, correlations with wind speed residuals showed no clear pattern. The theoretical study was based on the noise models of Brooks, Pope and Marcolini, and Lowson. Aerofoil boundary layer parameters were calculated using the program XFOIL. The study demonstrated that the method of calculation of these parameters has a very strong influence on the noise predictions; the most important issues being; i. whether free or forced boundary layer transition should be assumed ii. if free transition is assumed, the choice of the parameter N in the Tollmein-Schlichting equation iii. the chordwise position at which the aerofoil boundary layer parameters are specified.