Abstract
Research on broadband aerodynamic noise from wind turbine blades is becoming important in several countries. In this work, computer simulation of acoustic emissions from wind turbine blades are predicted using quasi empirical model for a three-bladed horizontal axis 3 MW turbine with blade length ~47 m. Sound power levels are investigated for source and receiver height of 80 m and 2 m above ground and located at a distance equal to total turbine height. The results are validated using existing experimental data for Siemens SWT-2.3 MW turbine having blade length of 47 m, as well as with 2.5 MW turbine. Aerofoil self-noise mechanisms are discussed in present work and results are demonstrated for wind speed of 8 m/s. Overall sound power levels for 3 MW turbine showed good agreements with the existing experiment data obtained for SWT-2.3 MW turbine. Noise map of single source sound power level, dBA of an isolated blade segment located at 75 %R for single blade is illustrated for wind speed of 8 m/s. The results demonstrated that most of the noise production occurred from outboard section of blade and for blade azimuth positions between 80° and 170°.
Highlights
Wind is one of the most inexhaustible natural sources of energy available
The model was developed to predict the far field sound pressure levels due to flow over fixed aerofoil source that were symmetric in nature
Tfohoruagihr tihse20 model was developed to assess sound power level (SPL) for flows over fixed aerofoil, it is applicable to rotating blades that operate at fairly high Reynolds number
Summary
Wind is one of the most inexhaustible natural sources of energy available. Wind energy has been harnessed for several purposes by humans from ancient times Manwell et al (2010). According to international wind turbine noise regulations, sound pressure levels of 35 dBA during day and 30 dBA at night located inside residences are allowed (Bastasch 2011). The purpose of this work is to provide an understanding of different noise mechanisms caused due to flow over the blades of a wind turbine. Numerical analysis was performed using quasi-empirical model BPM (Brooks et al 1989) to assess the multiple sources of noise mechanisms over the broad range of frequencies between 20 Hz and 10 kHz. The model was developed to predict the far field sound pressure levels due to flow over fixed aerofoil source that were symmetric in nature. The model was developed to predict the far field sound pressure levels due to flow over fixed aerofoil source that were symmetric in nature
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