Turbine Noise

The turbine is noisier than it should be. It produces two quite separate sounds, a whooshing noise as the blades rotate, and a humming or ringing noise. The whooshing is fine, no problem and as expected. It is only audible in high winds, and then you have to listen out for it to hear it. It also depends on the wind direction. The farmhouse is about 450 metres away from the turbine. The humming noise is more serious, in that it is more intrusive, and can be heard in a wider range of wind conditions. It appears that the fairly quiet noise from the generator and gearbox is resonating with the column of air inside the tower, and thus the tower is amplifying and broadcasting the noise. The solution is to put foam in the top of the tower, both to prevent the sound travelling down into the tower, and also to change the length of the air column in the tower and therefore reduce the resonance. This will be tried when the engineers come back to do the 6 month service. Watch this space for a resolution.