Torsional moment from tower

Wind & Water Structural Analysis
#1

Dear developers
In particular Mr Jonkman
I have a question about the aerodynamic loading consideration on the [size=120]Tower[/size].
1- Does Fast (in the aerodyn or elastodyn module) compute the torsional loading in the tower?
The wind generates loads: Drag (Cd), Lift (Cl) and pitching moment (Cm).
I’ve seen Aerodyn’s option to enable or disable this function (USE_CM or NO_CM). But I believe this function is only for the blade. In the tower configurations (NRELOffshrBsline5MW_Onshore_AeroDyn_Tower.dat) it only has the drag coefficient (Cd).
I searched the input files, but I didn’t find such an option.
I also looked in the technical material (tutorial), but I didn’t find a reference, if any equation relates and gets the Cm from the Cd.

Thank you a lot for your support

#2

Dear Carlos,

The tower aerodynamic load calculation in AeroDyn is very simple and assumes a cylindrical shape. So, there is no Cm computed on the tower for AeroDyn. That said, for operational cases, the aerodynamic loads on the rotor generally dominates over direct wind load on the tower, which is generally only impactful for parked/idling conditions when the rotor is not spinning, and the aerodynamic loads on the rotor can generate moments about the tower axis. Also, the drag force on the tower can also generate an aerodynamic moment on the tower because the drag force is applied in the deflected state, and so, the tower deflection can generate a moment arm for the tower drag force.

Best regards,

#3

Dear Mr Jonkman,
Thank you a lot for your very fast response!!!
:stuck_out_tongue: