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.
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?
Could be. As is said so often: physics doesn’t scale. Trailing edge eddies may not be the major source of the noise in this anyway - since these are pushing air not being pushed by it.
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.
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.
I can’t hear the word eddies without thinking Hitchhiker’s Guide
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?
So why don’t my CPU/case fans have serrated edges as well? Because they are too small?
Could be. As is said so often: physics doesn’t scale. Trailing edge eddies may not be the major source of the noise in this anyway - since these are pushing air not being pushed by it.
Yeah that makes sense I guess.
Some do, e.g. Noctua: https://noctua.at/en/vortex-control-notches
Trailing edge you say? So not designed to mince up birds, that’s a relief.
Oh they’ll still mince birds, just with the blunt side
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.