What is 'feathering' in aerofoil technology?

Question

I'm studying wind turbine technology at the moment. I'm stuck on the concept of feathering. It is exploited in order to ensure that a turbine will only go so fast in a high wind. But how does it work?

Answer 1

Feathering is an aviation term meaning to adjust the blades of a propeller so that they present the least forward air resistance. The angle of the propeller blade relative to the wind is called "pitch". The propeller blades of a wind turbine can vary their pitch in the same manner as many aircraft. The concept here is to take a constant amount of energy from the wind regardless of the amount of wind energy there may be at the time. In a turbine generator, energy and speed are related.

In wind turbines, pitch is used to maintain an approximately constant rotational speed (about 12 to 15 rpm) in varying wind speed conditions by varying the pitch.. The higher the wind velocity and thus the wind energy, the more feathering (lower pitch) is needed to keep the turbine from over-speeding. Less energy is taken from the wind.

When wind speeds are low, higher pitch is used to present more of the propeller blade surface to the wind and so transfer more wind energy to the blade.

Have you ever been to a wind farm? There's one near me. You can't believe how big those things are until you stand next to one.