## Rotor Aerodynamics

To study how the wind moves relative to the rotor blades of a wind turbine, we have fixed red ribbons to the tip of the rotor blades of our model wind turbine, and yellow ribbons some 1/4 out the length of the blade from the hub. We then let the ribbons float freely in the air (in the cartoon we abstract from the air currents created by the blades themselves, and the centrifugal force).
The two images on this page give you one view from the side of the turbine, and another view from the front of the turbine.
Since most wind turbines have constant rotational speed, the speed with which the tip of the rotor blade moves through the air (the tip speed) is typically some 64 m/s, while at the centre of the hub it is zero. 1/4 out the length of the blade, the speed will then be some 16 m/s.
The yellow ribbons close to the hub of the rotor will be blown more towards the back of the turbine than the red ribbons at the tips of the blades. This is obviously because at the tip of the blades the speed is some 8 times higher than the speed of the wind hitting the front of the turbine.