Author: | Noise
NASA Technical Memorandum 100528
General Wind Turbine Acoustics Publications
Wind Turbine Noise Generation, Prediction and Measurements
Wind Turbine Noise Propagation
Effects of Wind Turbine Noise on People and Communities
Effects of Wind Turbine Noise on Buildings
Wind Turbine Noise Measurement Technology
Kelly, N. D.; McKenna, H. E.; Hemphill, R. R.; Etter, C. L.; Garrelts, R. L.; and Linn, N. C.: Acoustic Noise Associated with the MOD-1 Wind Turbine: Its Source, Impact and Control. SERI/TR-635-1166, February 1985.
Extensive research by staff of the Solar Energy Research Institute and its suhcontractors conducted to establish the origin and possible amelioration of acoustic disturbances associated with the operation of the DOE/NASA MOD-1 wind turbine installed in 1979 near Boone, North Carolina, is summarized. Results have shown that the source of this acoustic annoyance was the transient, unsteady aerodynamic lift imparted to the turbine blades as they passed through the lee wakes of the large, cylindrical tower supports. Nearby residents were annoyed by the low-frequency acoustic impulses propagated into the structures in which the complainants lived. The situation was aggravated further by a complex sound propagation process controlled by terrain and atmospheric focusing. Several techniques for reducing the abrupt, unsteady blade load transients were researched and are discussed.
Hillshire, W. L., Jr., and Zorumski, W. E.: Low-Frequency Acoustic Propagation in High Winds. Proceedings of Noise Con 87, June 1987.
The propagation of low-frequency noise outdoors was studied using as the source a large (80-m diameter) 4-megawatt horizontal axis wind turbine. Acoustic measurements were made with low-frequency microphone systems placed on the ground at downwind sites ranging from 300 m to 20,000 m and at upwind sites ranging from 200 m to 4,000 m away from the wind turbine. The wind turbine fundamental was 1 Hz and the wind speed was generally 12-15 m/s at the hub height (80 m). The harmonic levels, when plotted versus propagation distance, exhibit a 6dB per doubling of distance devergence in the upwind direction and a 3 dB per doubling of distance divergence in the downwind direction. Predictions of both ray tracing and normal mode theoretical models supported the downwind cylindrical spreading. A consequence of this is that low-frequency noise signals propagate further in the presence of wind in the downwind direction. The measured frequency dependence and effect of boundary layer shape on the downwind horizontal exponential attenuation coefficients were consistent with normal mode theory. However, the predicted attenuation coefficients were less than those measured. In the upwind direction, no low-frequency acoustic shadow zone was observed; the low-frequency acoustic signals propagated upwind exhibited spherical spreading.
Stephens, D. G.; Shepherd, K. P.; Hubbard, H. H.; and Grosveld, F. W.: Guide to the Evaluation of Human Exposure to Noise from Large Wind Turbines. NASA TM 83288, March 1982.
This document is intended for use in designing and siting future large wind turbine systems as well as for assessing the noise environment of existing wind turbine systems. Guidance for evaluating human exposure to wind turbine noise is provided and includes consideration of the source characteristics, the propagation to the receiver location, and the exposure of the receiver to the noise. The criteria for evaluation of human exposure are based on comparisons of the noise at the receiver location with the human perception thresholds for wind turbine noise and noise-induced building vibrations in the presence of background noise. Five appendices are included to present background information used in preparing the guide. These appendices cover wind turbine noise source characteristics, human perception thresholds, response of buildings to noise, atmospheric propagation and example calculations.
Hubbard, H. H.; and Shepherd, K. P.: Response Measurements for Two Building Structures Excited by Noise from a Large Horizontal Axis Wind Turbine Generator. NASA CR 172482, November 1984.
Window and wall acceleration measurements and interior noise measurements were made for two different building structures during excitation by noise from the WTS-4 horizontal axis wind turbine generator operating in a normal power generation mode. Wind turbine noise input pulses resulted in acceleration pulses for the wall and window elements of the two test buildings. Responses of a house trailer were substantially greater than those for a building of sturdier construction. Peak acceleration values correlate well with similar data for houses excited by flyover noise from commercial and military airplanes and helicopters, and sonic booms from supersonic aircraft. Interior noise spectra have peaks at frequencies corresponding to structural vibration modes and room standing waves; and the levels for particular frequencies and locations can be higher than the outside levels.
Hubbard, H. H.; and Shepherd, K. P.: The Helmholtz Resonance Behavior of Single and Multiple Rooms. NASA CR 178173, September 1986.
This paper presents the results of some exploratory measurements of the noise fields inside rooms which are excited to resonance either acoustically or mechanically. The data illustrate the nature and extent of the sound pressure level enhancements in single rooms and with multiple rooms having flexible walls. For such conditions the sound pressure levels in the room were essentially uniform and in phase. Variability of up to 20 dB was measured tn a room, hallway complex having significant acoustic interactions. Resonant frequency prediction methods which work well at model scale give only fair results for rooms.
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