Took the weans a walk away up the back of The Three Towns in Ayrshire where they are installing these big bad boys.

  • GreyShack@lemmy.world
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    1 year ago

    They disrupt the trailing edge eddies - which is what causes any noise - and so make them quieter. They are often fitted in areas where sound might be a particular issue.

    • kev@mcr.town
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      1 year ago

      I can’t hear the word eddies without thinking Hitchhiker’s Guide

      “Eddies,” said Ford, “in the space-time continuum.”

      “Ah,” nodded Arthur, “is he. Is he.”

    • Trail@kbin.social
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      1 year ago

      So why don’t my CPU/case fans have serrated edges as well? Because they are too small?

    • Finnbot@lemmy.worldOP
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      1 year ago

      They are surrounding a farm with hunners of cows in multiple fields, so I wonder if the noise is quite scary for them, hence efforts to make them quieter. Or the farmer insisting. Are they usually quite loud?

    • Gormolius@lemmy.one
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      1 year ago

      Trailing edge you say? So not designed to mince up birds, that’s a relief.

        • GreyShack@lemmy.world
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          1 year ago

          Most of the bird deaths are not actually physical strikes - it is a result of the massive change of air pressure as the blades pass at speed. Evidently painting one of the blades black - or some contrasting colour - keeps a lot of the birds well away.

            • GreyShack@lemmy.world
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              1 year ago

              I realise that I had mis-remembered this. It is primarily bat deaths that are caused by the air pressure changes around turbines - not birds. This is because bats have a particularly large and thin lung internal membranes which gives them high efficiency. The rapid decompression in the immediate wake of the turbine blades - particularly towards the tips, which are the fastest moving part of course - damages this membrane.

              Birds have more compact lungs and hollow bones which aid in their breathing - a different solution to the efficiency problem and one that is not as susceptible to these pressure changes.

  • RoadieRich@midwest.social
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    1 year ago

    It reduces the turbulence at the trailing edge, reducing noise. Bernouli’s principle dictates that part of the force on the blade is due to the airflow on each side moving at different speeds, if the crashed into each other all at once, you’d get a lot of turbulence, and hence noise. The serrations ensure that the two flows meet over a longer distance, reducing said turbulence.

  • buhala@sopuli.xyz
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    1 year ago

    I’m sure that makes sense for some reason but all I can think of is giant comb.

    Is it true they make noise? Or were they not running at the time?

    • sideone@lemmy.worldM
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      1 year ago

      Is it true they make noise?

      We have some quite close (a few miles away) and I’ve cycled right past them. I’ve never heard anything from them.

      • Greyscale@lemmy.sdf.org
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        1 year ago

        Riding my moped past these and I can tell you they make swooping noises, especially if they’re aimed 90 degrees to you. These windmills are quite small and old, however, and are quite low. Its a bit intimidating seeing something that massive moving that fast, that close.

        They make a rainbow though

        Apparently one collapsed recently

  • 1nk@kbin.social
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    1 year ago

    As others have said, mostly about noise reduction. There’s actually work looking whether the same concept could be developed for electric aircraft.