The First Wind Turbine Noise Conference was held in Berlin in 2005 and much to one’s surprise the 7th Wind Turbine Noise Conference was held in Rotterdam. The fact that wind turbine noise seems to increase as an issue than decrease is somewhat disappointing.
Screaming Rabbits made their first appearance during the first presentation of the conference during consideration of sources of contamination of noise measurements where a fine photograph of a screaming rabbit was presented. Subsequent to this they appeared frequently as an identified source of contamination of measurements, be they in the field or laboratory. (Who says acousticians can’t have a joke!) Little did our first speaker know the impact of that picture upon the rest of the conference?
Amplitude Modulation was considered during 3 separate sessions with the emergence that the IoA AM Reference Method for rating AM was being adopted by many researchers when considering and measuring this character of sound from wind turbines. A paper presented by Mr Fukushima (Comparison of the IoA Method and Japanese F-S method for quantitative assessment of amplitude modulation of wind turbine noise. A study based on the field measurement results in Japan) provided good validation of the method and that in general it resulted in a higher assessed level of AM for the same input signal than that derived from the F-S method.
During sessions dealing with “Low Frequency and Tones” and “Infrasound” the feeling from the floor of the chamber was concern that concepts such as magnitude seemed to be missing from some papers and that the imprecise and perhaps lax use of language when describing measured levels could lead a lay person to consider levels to be problematic when measured levels are 60 – 80 dB below the thresholds of perception. Comments during Q&A after the sessions would indicate that more time (and money) spent on considering issues within the audible range of sound might be more constructive than searching for a solution in a frequency range which is generally inaudible for humans for a source such as a wind turbine.
The Thursday Hall 2 sessions dealing with aerodynamic noise sources, trailing edges, serrations and source identification was a paradise for those looking for equations, boundary layer thickness and flow separation calculations. It was also a room which was filled with a lot of happy people talking about something which enthused them all. It would appear there is still much to learn about how trailing edge serrations interact with the turbulent flow and some of the visualisation techniques, be they CFD or from direct camera measurements are very informative. I look forward to attending this session again at the next Wind Turbine Noise Conference 2019 which is thought likely to be in Canada or a middle European Country.
Let’s hope the Europeans let us in by then!
By Malcolm Hayes
To see our full conference review, click here.
15 May 2017Back to news