Method for predicting impulsive noise generated by wind-turbine rotors
Large wind turbines can generate both broad-band and impulsive noises. These noises can be controlled by proper choice of rotor design parameters such as rotor location with respect to the supporting tower, tower geometry, and tip speed. A method has been developed to calculate the impulsive noise generated when the wind turbine blade experiences air forces that are periodic functions of the rotational frequency. This phenomenon can occur when the blades operate in the wake of the support tower and the non-uniform velocity field near the ground due to wind shear. Results from this method are compared with measured sound spectra taken at locations of one to two rotor diameters from the DOE/NASA Mod-1 wind turbine. The calculated spectra generally agree with the measured data in both the amplitude of the predominant harmonics and the roll-off rate with frequency. Measured sound pressure levels far from the Mod-1 (15 rotor diameters), however, are higher than predicted. Simultaneous measurements in the near and far field indicate the propagation effects can enhance the sound levels by more than 10 dB above that expected by spherical dispersion. These propagation effects are believed to be due to terrain and atmospheric characteristics of the Mod-1 site.
- Research Organization:
- NASA Lewis Research Center, Cleveland, OH (United States)
- DOE Contract Number:
- AI01-76ET20320
- OSTI ID:
- 5348619
- Report Number(s):
- DOE/NASA/20320-36; NASA-TM-82794; CONF-820534-1; ON: DE82012574
- Resource Relation:
- Conference: International conference on noise control engineering, San Francisco, CA, USA, 17 May 1982
- Country of Publication:
- United States
- Language:
- English
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