What should the rotational speed be for the Performance Coefficients calculation?
Bladed versions affected: all Bladed versions supporting Peformance Coefficients calculation
Date of last article update: 16 March 2023
If the rotor is rigid, the only thing rotational speed does is to change the Reynolds number, so airfoil properties will also change if they have been defined to interpolate on Reynolds number. In general for a rigid rotor, the performance coefficient results are not very sensitive to the rotor speed.
However, since Bladed 4.7 it has been possible to define flexible blades for this calculation type. Then, the rotational speed does matter, because loads on the blade depend on the rotational speed and that can deflect the blade and change the angle of attack. This leads to a different aerodynamic loads and different performance coefficients.
So, if flexibility is included, it will be useful to run Performance Coefficients calculation with different rotational speeds and find the one that corresponds to the wind speed you are interested in.