Aerodynamic Torque calculation

Wind & Water Computer-Aided Engineering Software Tools
2

Dear Alireza,

You cannot currently output the aerodynamic torque directly from FAST; instead, the reaction torque within the shaft can be output (LSShftTq=RotTorq), as explained in the forum topic you referred to: Resistant moment of the rotor and of the electric generator.

Without changing the source code to output the aerodynamic torque directly, you could derive the aerodynamic from available FAST outputs in a couple ways:

  1. Add the rotor inertia term (due to acceleration/deceleration) to the reaction torque output. That is, solve the equation from the forum topic you referred to, LSShftTq = T_Aero – J_Rotor*Alpha, for T_Aero. If the rotor is flexible, this result will only be approximate, but may be accurate enough for your needs.

  2. Time-average the reaction torque output over time scales large enough to average-out the variations in rotor motion; this result should be the average aerodynamic torque.

Best regards,