IEA 15 MW RWT: fixed foundations. Discrepancy in RtAeroPwr among OLAF and BEMT

Wind & Water Rotor Aerodynamics
10

Thank you both for your work and comments.

For (my own) reference, I’m writing down the parameters given by Riccardo for IEA 15MW, trying to give dimensionless values whenever possible:

  • TSR=9 (U0=10.59 m/s, Omega=7.56 rpm, R=117 m)
  • CT=0.8, CP=
  • dpsi = 6 Omega dt = 6 deg, (delta t=0.132 s)
  • nNWPanel = 420 = 7 rotations (2520 deg)
  • nFWpanel = 600 = 10 rotations (3600 deg) (also called “WakeLength”)
  • nFWPanelsFree = 200 = 3.3 rotations (1200 deg)
  • RegDeterMethod =3 (i.e. based on dr , with dr = 0.02 R
  • RegFunction =3
  • WakeRegMethod=3
  • WakeRegFactor=0.4 (dr, with dr = 0.02 R)
  • BladeRegFactor =0.8 (dr, with dr = 0.02 R)
  • CoreSpreadEddyVisc=1000

Ideally, the wake extents in terms of downstream distance would be used, but this information is hard to use. For different operating conditions, the CT and the axial induction change, which affects the distance convected by the wake. In theory, we should try and keep the convected distance (of the near wake and far wake) more or less the same across operating conditions. Therefore the n*Panels might need to change slightly with operating conditions.

I would hope that the regularization parameters do not need to change. The rated conditions are usually the ones with fairly large CT (therefore with large wake extension and slow wake convections), they are usually the most challenging ones to simulate.