Problem of Beamdyn coupled with Aerodyn

Wind & Water Rotor Aerodynamics
1

Dear Jason,

I am trying to model a fixed foudation wind turbine by OpenFAST_X64.exe -v1.0.0 with setting (CompElast=2, CompInflow=1,CompAero=1,CompServo=0).And the DT(module time step) is 0.0005 s in global. OpenFast is aborted with the following error.

[b]FAST_Solution:FAST_AdvanceStates:AD_UpdateStates:BEMT_UpdateStates(node 7, blade
1):BEMT_UnCoupledSolve:There is no valid value of phi for these operating conditions: Vx =
19.885, Vy = -852.47, rlocal = 12.334, theta = 0.57915, geometric phi = 3.1183
BEMT_UpdateStates(node 8, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these
operating conditions: Vx = -22.125, Vy = -1393.4, rlocal = 14.758, theta = 0.54525, geometric phi
= -3.1257

FAST encountered an error at simulation time 0.248 of 60 seconds.
Simulation error level: FATAL ERROR

Aborting OpenFAST.
[/b]
I got that these issues have been fixed in AeroDyn v15.04 and newer, including in the release of OpenFAST v1.0 from some other topics. but I still got this kind of problem. I guess I have some problems in my model.
could you please give me some suggestions to modify my model?

Best regards,

2

Dear Guo,

With the AeroDyn updated in OpenFAST v1.0.0 (selected by CompAero = 2, not CompAero = 1), OpenFAST/AeroDyn will no longer abort if there is “no valid value of phi”. A warning message is displayed when this happens (although the situation should happen much less frequently), but the software is now robust enough to choose a suitable phi and continue without aborting. If your OpenFAST v1.0.0 model is aborting, it is not directly because there is no valid value of phi. Are you there other messages written to the screen e.g. an error about the lack of convergence in BeamDyn? Can you share the complete set of messages OpenFAST writes to the screen?

Best regards,

3

Dear Jason,

Thank you very for your kind reply.

The complete messages OpenFAST writes to the screen is very long, so I just attached the last print. You are right. The warning message of " no valid value of phi" happened frequently but not lead to software aborting. And I found that Vy became bigger and bigger. Finally, “Solution does not converge after the maximum number of iterations” leaded to software aborting.

FAST_Solution:FAST_AdvanceStates:AD_UpdateStates:BEMT_UpdateStates(node 7, blade
1):BEMT_UnCoupledSolve:There is no valid value of phi for these operating conditions: Vx =
41.353, Vy = -1804, rlocal = 13.096, theta = 0.58614, geometric phi = 3.1187
BEMT_UpdateStates(node 8, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these
operating conditions: Vx = -33.154, Vy = -2583.1, rlocal = 15.379, theta = 0.55782, geometric phi
= -3.1288
BEMT_UpdateStates(node 9, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these
operating conditions: Vx = -87.492, Vy = -2991.5, rlocal = 17.661, theta = 0.53017, geometric phi
= -3.1124
BEMT_UpdateStates(node 10, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these
operating conditions: Vx = -121.12, Vy = -3029.9, rlocal = 19.941, theta = 0.50801, geometric phi
= -3.1016
BEMT_UpdateStates(node 11, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these
operating conditions: Vx = -132.92, Vy = -2696.7, rlocal = 22.218

FAST_Solution:FAST_AdvanceStates:BD_GA2:BD_DynamicSolutionGA2:Solution does not converge after
the maximum number of iterations
FAST_AdvanceStates:AD_UpdateStates:BEMT_UpdateStates(node 1, blade 1):BEMT_UnCoupledSolve:There
is no valid value of phi for these operating conditions: Vx = -12.852, Vy = -2612.4, rlocal =
2.3235, theta = 0.38558, geometric phi = -3.1367
BEMT_UpdateStates(node 2, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these
operating conditions: Vx = -47.774, Vy = -3219.8, rlocal = 2.9162, theta = 0.39557, geometric phi
= -3.1268
BEMT_UpdateStates(node 3, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these
operating conditions: Vx = -78.481, Vy = -3725.6, rlocal = 3.5058, theta = 0.40559, geometric phi
= -3.1205
BEMT_UpdateStates(node 4, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these
operating conditions: Vx = -130.28, Vy = -4489.8, rlocal = 4.7989, theta = 0.436, geometric phi =
-3.1126
BEMT_UpdateStates(node 5, blade 1):BEMT_UnCoupl

FAST encountered an error at simulation time 0.2525 of 60 seconds.
Simulation error level: FATAL ERROR

Aborting OpenFAST.

Best regards,

4

Dear Guo.Wu,

Yes, I agree that it is the lack of convergence in BeamDyn that is the fatal error causing the simulation to abort.

To solve this problem, I would first make sure that you can run the BeamDyn model in standalone BeamDyn. Can you get BeamDyn to converge with the same structural model in standalone BeamDyn with various rotational speeds and applied loads? Once you debug any problems with the model in standalone BeamDyn, can you get the model to converge in coupled FAST simulations with smaller glue code time steps?

Best regards,

5

Dear Jason,

After debug again and again, I found that the aborting problem of my model is generated by wrong definition of section Mass Matrix of blade. The iEdg should be usually larger than iFlp, and that is the case in Nrel 5MW model. But iEde is smaller than iFlp in my model. After fixed this problem, the model can run smoothly.

Thank your very much for your help.

Best regards,