This thesis is an investigation into the nature of aerodynamic noise emitted by wind turbine blades as they rotate. The main aims of this work were a follows: 1. to give an account of theoretical and experimental work on aerodynamic noise emission from aerofoils, 2. to examine experimental data from a variety of different wind turbines, and to extract from these comparisons information about the influence of different blade design parameters on noise emission, 3. to examine experimentally the influence of tip angle of attack on noise using a new method, 4. to use the information gleaned from (1) and (2) to write a noise prediction program which can be used for any design of horizontal axis wind turbine operating under any reasonable conditions, 5. to compare the predictions with experimental data. The first three chapters consist of background information, concerning the development of wind farms, the noise regulations with which they must comply and the theory of aerodynamic noise emission. The following four chapters contain new work, the principal findings being: 1. Comparisons of experimental noise data from different designs of wind turbines indicate that low frequency noise (less than 250 Hz) is the most sensitive to tip speed, while frequencies between 250 and 630 Hz are less affected, and frequencies in the kHz range are almost unaffected by tip speed. This conflicts with existing noise prediction codes. 2. Noise may increase slightly with tip angle of attack, but this is not pronounced for modern blades with sharp trailing edges. However, there is a significant reduction in high frequency noise (above 1.5 kHz) as the tip angle of attack is reduced in constant winds. In addition, for the turbine studied, a broad aerodynamic peak centred on 630 Hz was observed when the tip angle of attack was reduced. 3. A rotor noise prediction code has been written, which gives accurate results over a range of tip speeds.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:649768 |
| Date | January 1994 |
| Creators | Dunbabin, Penny |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/14768 |
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