Wind turbine amplitude modulation noise due to time-dependent interference
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Acoustics 2015 Hunter Valley 15-18 November 2015Abstract: Trailing edge noise from a turbine blade comprises sources which move in a circle so that the direct sound path and ground reflected sound paths to a receiver periodically vary. At any one listener location, there is therefore a fluctuating intensity. A simple ray model shows that this mechanism enhances the characteristics of wind turbine amplitude modulation noise, and can lead to a sharper onset of the higher intensity sound at some frequencies. This time-dependent interference mechanism does not depend on intermittent stall, although increased source intensity obviously leads to increased modulation noise.
Trailing edge noise from a turbine blade comprises sources which move in a circle so that the direct sound path and ground reflected sound paths to a receiver periodically vary. At any one listener location, there is therefore a fluctuating intensity. A simple ray model shows that this mechanism enhances the characteristics of wind turbine amplitude modulation noise, and can lead to a sharper onset of the higher intensity sound at some frequencies. This time-dependent interference mechanism does not depend on intermittent stall, although increased source intensity obviously leads to increased modulation noise.