Unsteady Aerodynamics, Dynamic Stall and Dynamic Wake in AeroDyn 15

Wind & Water Rotor Aerodynamics
1

Hi,
when I get the warning “Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 1, Blade = 1”, does that mean that only the dynamic stall feature is disabled for that blade and foil section or also the dynamic inflow/wake effect is turned off?

I am asking, because I’m actually looking for a way to turn off only dynamic stall without turning off dynamic wake. Ideally I would even like to selectively turn off dynamic stall only for some foil sections / nodes, e.g. around the blade tip where the foils have very small chord length which, in combination with the high effective inflow speed, leads to extremely small time constants.

If setting C_nalpha to zero does in fact turn off dynamic stall and dynamic wake, are there maybe other parameters that I could use to effectively turn off only dynamic stall?

2

Dear Jens,

Yes, the warning about “turning off unsteady aerodynamics” only applies to the unsteady airfoil aerodynamics (UA, dynamic stall) model; dynamic wake will still be enabled if it was at initialization.

To disable UA at a given airfoil section, you can set C_nalpha = 0 or you can set UACutOut = 0.

Best regards,

3

Great, thanks a lot!