Dear all,
recently I downloaded IEA 22MW model from github and changed input parameters for DLC 61 and 62 simulations. When I am looking at results, I found strange spike in some cases, as following. For one set of setting, I have 6 seeds. However only one out of six has this strange spike.
Thanks very much!
Best regards,
Mengying
Dear @Mengying.Xu,
AeroDyn output RtFldCq (or, equivalently, RtAeroCq), is computing by integrating the total aerodynamic torque across the rotor (RtAeroMxh) and dividing by 1/2 * AirDens * RtArea * R * RtVAvgxh ^2, where RtArea is the instantaneous rotor-swept area and RtVAvgxh is the rotor-disk-averaged relative wind speed normal to the disk. I would suggest outputting the invididual contributions of the calculation (RtAeroMxh, RtArea, and RtVAvgxh) to see if any of these are spiking as well.
Is there something happening to the turbine motion or wind at the time of the spike?
Best regards,
Dear Dr. Jonkman,
thanks for your quick reply. RtAeroMxh and RtVAvgxh do have spikes at the same time, especially for RtVAvgxh, as following figures show. I am wondering why it happened and also output blade tip and platform motion. It shows that blade 2 axial tip deflection(TipDzc2) and platform pitch are having extreme values simultaneously. Does it mean the simulation is corret? Then why are results from other seeds different?
Thanks again~
Best regards,
Mengying
Dear @Mengying.Xu,
Well, that explains the source of the spike.
Whether the results are “correct” depends on the model set up. Have you disabled wake and unsteady airfoil aerodynamics effects in AeroDyn for these load cases? Have you idled the rotor, feathered the blades (e.g., to 90deg pitch), and disabled the controller? What are the out-of-plane and in-plane blade-tip deflections doing? How about the tower-top deflections? What is the rotor speed?
Best regards,
Dear Dr. Jonkman,
sorry for late reply. Yes, I have set CompServo=0,Wake_Mod=0,UA_Mod=0,AoA34=False, BlPitch=89, RotSpeed=0.1,GenDOF=False, YawDoF=True.
Blade tip deflections and tower top deflections are as following:
Thanks again and best regards,
Mengying
Dear @Mengying.Xu,
Most of your settings are fine, but I’m not sure why you are forcing a 0.1 rpm slow roll of rotor with GenDOF = FALSE. I would normally expect this large of turbine to be idling, with GenDOF = TRUE and RotSpeed = 0 (this requires that you disable torque control by setting GenTiStr = TRUE with TimGenOn > TMax in ServoDyn).
Best regards,
Dear Dr. Jonkman,
I vaguely remember that I set Rotspeed=0.1 to solve some simulation problem when I first learned using OpenFast. After that I keep setting it in DLC6. Today I runned two cases(1 as orignal case): 2-only change RotSpeed to 0; 3- GenDOF = TRUE,RotSpeed = 0, GenTiStr = TRUE with TimGenOn > TMax in ServoDyn. It shows that case 2 does not have spike any more, yet case 3 have spike in another time.
Thanks again and best regards,
Mengying
Dear @Mengying.Xu,
Sounds fine. I don’t see much point in looking at the Cp output when the rotor is parked or idling anyway.
Best regards,
