Swept blade planform as it affects impulse noise

Wind & Water General
1

Hi,
I was wondering if anyone has had experience with a swept blade planform as if affects tower shadow impulse noise on downwind turbines? My assumption is each blade would progressively enter the tower shadow and the noise spectrum would be spread over a longer time period possibly dulling the characteristic impulse emission.

Thanks, Robert

2

Dear Robert,

I would agree with your assumption, but can’t give you any hard numbers for resulting decibal reduction.

Best regards,

3

Thanks, Jason, for your reply. It may be that along with a reduction in decibels there would be a reduction in fatigue loading. I currently run a set of 23’ long blades on my 45 kW downwind turbine. These were designed by the late E. Eugene Larrabee. They are coned 6 degrees downwind. I have had fatigue issues with tubular blade shafts and now use solid 4340 shafts.