aérofrein
/aʒystmˈɑ̃ də- limˈaʒ dy- ˈsɛʁkl vɛʁtikˈal/
n
English: aerodynamic brake · 气动刹车
Sens：Emergency braking system; it consists of shutters attached to the blades, which automatically deploy when the wind turbine gathers too much speed.