FAST_Solution:FAST_AdvanceStates:AD_UpdateStates:SetInputs:TwrInfl:getLocalTowerProps:Tower strike.

[tatesnow]

When I simulate with 25m/s turbulent wind, the following error occurs, can you give me some suggestions?

OpenFAST-v3.0.0
Compile Info:

• Compiler: Intel(R) Fortran Compiler 1900
• Architecture: 64 bit
• Precision: single
• OpenMP: No
• Date: Jun 23 2021
• Time: 21:25:05
  Execution Info:
• Date: 01/06/2022
• Time: 17:13:27+0800

OpenFAST input file heading:
FAST Certification - Test #18: NREL 5.0 MW Baseline Wind Turbine (Onshore)

Running ElastoDyn.
Nodal outputs section of ElastoDyn input file not found or improperly formatted.
Running AeroDyn.
AD15 Nodal Outputs: Nodal output section of AeroDyn input file not found or improperly formatted.
Skipping nodal outputs.
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 1, blade 1)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 2, blade 1)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 3, blade 1)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 4, blade 1)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 1, blade 2)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 2, blade 2)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 3, blade 2)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 4, blade 2)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 1, blade 3)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 2, blade 3)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 3, blade 3)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 4, blade 3)
Running InflowWind.

Reading a 39x34 grid (190 m wide, 7.5 m to 172.5 m above ground) with a characteristic wind
speed of 25 m/s. This full-field file was generated by TurbSim (v2.00.07a-bjj, 14-Jun-2016) on
04-Jan-2022 at 20:24:06.

Processed 12420 time steps of 20-Hz full-field data (period of 621 seconds).
Running ServoDyn.
Running ServoDyn Interface for Bladed Controllers (using Intel Visual Fortran for Windows, ).
Using legacy Bladed DLL interface.
Time: 0 of 60 seconds.

FAST_Solution0:CalcOutputs_And_SolveForInputs:SolveOption2:SrvD_CalcOutput:DLL_controller_call:Run
ning with torque and pitch control of the NREL offshore 5MW baseline wind turbine from DISCON.dll
as written by J. Jonkman of NREL/NWTC for use in the IEA Annex XXIII OC3 studies.

FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption2:RotCalcOutput:BEMT_CalcOutput(node 5,
blade 1):UA_CalcOutput:UA_BlendSteady:Temporarily turning off UA due to high angle of attack or
low relative velocity. This warning will not be repeated though the condition may persist.

FAST_Solution:FAST_AdvanceStates:ED_ABM4:ED_CalcContStateDeriv:SetCoordSy:Small angle assumption
violated in SUBROUTINE SmllRotTrans() due to a large blade deflection (ElastoDyn SetCoordSy). The
solution may be inaccurate. Simulation continuing, but future warnings from SmllRotTrans() will
be suppressed.
Additional debugging message from SUBROUTINE SmllRotTrans(): 0.5125 s

FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption2:RotCalcOutput:BEMT_CalcOutput(node 19,
blade 2):UA_CalcOutput:Mach number exceeds 0.3. Theory is invalid. This warning will not be
repeated though the condition may persist.

FAST_Solution:FAST_AdvanceStates:AD_UpdateStates:SetInputs:TwrInfl:getLocalTowerProps:Tower
strike.

OpenFAST encountered an error at simulation time 0.7625 of 60 seconds.
Simulation error level: FATAL ERROR

Aborting OpenFAST.

[jjonkman]

Dear @tatesnow,

Your OpenFAST model appears to be numerically unstable. It looks like you are running the NREL 5-MW land-based wind turbine example. Can you clarify what you changed in this model relative to the model available from the r-test: https://github.com/OpenFAST/r-test/tree/main/glue-codes/openfast/5MW_Land_DLL_WTurb?

Best regards,

[tatesnow]

Dear @jjonkman,
Get it! Thank you very much!
Best regards,

[tatesnow]

Dear @jjonkman ,
According to your suggestions, I modified the initial speed and pitch angle of the input file, and then it works smoothly.
But there are still some warming information, although it does not affect the result, but I still want to know the reason

Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 1, blade 1)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 2, blade 1)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 3, blade 1)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 4, blade 1)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 1, blade 2)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 2, blade 2)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 3, blade 2)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 4, blade 2)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 1, blade 3)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 2, blade 3)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 3, blade 3)
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. (node 4, blade 3)

[jjonkman]

Dear @tatesnow,

Regarding the "C_nalpha is 0" warnings, you can ignore these, as discussed in a previous OpenFAST issue: #268.

Best regards,

[lin990316]

Dear @jjonkman
I noticed in your reply about the initial rotor speed and initial blade angle settings for different wind speeds, which I seem to have missed in my previous calculations, but I don't seem to have found any detailed information about this for the IEA 15MW turbine that I am studying. Can you tell me if the table in Fig. 9.1 that you mentioned applies to other turbines, and if this figure doesn't apply to other turbines, where can I find it? Where can I find pictures of the 15MW wind turbine?
Best regards,

[jjonkman]

Dear @lin990316,

It looks like you asked a similar question in the following OpenFAST issue: #2047; I've responded there.

Best regards,

[Crystal0912]

I have a similar question with you .When I simulate with 12m/s turbulent wind, the following error occurs, can you give me some suggestions?

---

FAST (v8.16.00a-bjj, 27-Jul-2016)
Copyright (C) 2016 National Renewable Energy Laboratory
This program comes with ABSOLUTELY NO WARRANTY. See the "license.txt" file distributed with this
software for details.

---

Running FAST (v8.16.00a-bjj, 27-Jul-2016), compiled as a DLL S-Function for Simulink as a 64-bit
application using single precision
linked with NWTC Subroutine Library (v2.09.00, 23-Jul-2016)
Heading of the FAST input file:
FAST Certification Test #19: NREL 5.0 MW Baseline Wind Turbine with OC3 Monopile RF
Configuration, for use in offshore analysis
Running ElastoDyn (v1.04.00a-bjj, 26-Jul-2016).
Running AeroDyn (v15.03.00, 27-Jul-2016).
Running AirfoilInfo (v1.01.00a-bjj, 5-Apr-2016).
Running BEM (v1.02.00, 29-Jun-2016).
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 1, Blade = 1
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 2, Blade = 1
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 3, Blade = 1
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 4, Blade = 1
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 1, Blade = 2
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 2, Blade = 2
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 3, Blade = 2
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 4, Blade = 2
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 1, Blade = 3
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 2, Blade = 3
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 3, Blade = 3
Warning: Turning off Unsteady Aerodynamics because C_nalpha is 0. BladeNode = 4, Blade = 3
Running InflowWind (v3.03.00, 26-Jul-2016).
Opening InflowWind input file: .\5MW_Baseline/NRELOffshrBsline5MW_InflowWind_12mps.dat
Reading a 15x15 grid (145 m wide, 17.5 m to 162.5 m above ground) with a characteristic wind
speed of 18 m/s. This full-field file was generated by TurbSim (v1.06.00, 21-Sep-2012) on
23-Nov-2021 at 20:32:24.
Processed 12162 time steps of 20-Hz full-field data (608.05 seconds).
Running ServoDyn (v1.06.00a-bjj, 26-Jul-2016).
Running ServoDyn Interface for Bladed Controllers (using Intel Visual Fortran for
Windows/Matlab, 14-Oct-2015).
Running HydroDyn (v2.05.01, 27-Jul-2016).
Generating incident wave kinematics and current time history.
Calculating second order difference frequency wave kinematics.
Calculating second order sum frequency wave kinematics.
Running SubDyn (v1.03.00, 11-Apr-2016).
Calculating Internal Modal Eigenvectors

FAST_InitializeAll:SrvD_Init:ValidatePrimaryData:Yaw angle and rate are not commanded from Simulink model.
ValidatePrimaryData:Pitch angles are not commanded from Simulink model.
ValidatePrimaryData:Generator torque and power are not commanded from Simulink model.
ValidatePrimaryData:HSS brake is not commanded from Simulink model.
Timestep: 0 of 100 seconds.
FAST completed.
An error occurred while running the simulation and the simulation was terminated
Caused by:
Error reported by S-function 'FAST_SFunc' in 'Program/FAST Nonlinear Wind Turbine/S-Function':
FAST_Solution:FAST_AdvanceStates:AD_UpdateStates:BEMT_UpdateStates(node 10, blade 1):BEMT_UnCoupledSolve:DeterminePhiBounds:There is no valid value of phi for these operating conditions! Vx = -5.5312, Vy = 45.188, rlocal = 32.232, theta = 0.18825

[Crystal0912]

Especially for this :---Caused by:
Error reported by S-function 'FAST_SFunc' in 'Program/FAST Nonlinear Wind Turbine/S-Function':
FAST_Solution:FAST_AdvanceStates:AD_UpdateStates:BEMT_UpdateStates(node 10, blade 1):BEMT_UnCoupledSolve:DeterminePhiBounds:There is no valid value of phi for these operating conditions! Vx = -5.5312, Vy = 45.188, rlocal = 32.232, theta = 0.18825

[Crystal0912]

Dear @jjonkman,

Thanks for your kind help and timely responses all the time! I will learn from the link you gave.

Best regards,

[Crystal0912]

Dear @jjonkman,

Sorry to bother you so frequently. I really use AeroDyn v15. Through learning, I find that if I want to simulate blade structural damage（Blade fault ）, I should change the factors “AdjBlMs, AdjFlSt，AdjEdSt and BMassDen ，FlpStff，EdgStff ”. Am I right？If I understand correctly, how should I revise these parameters? What is their relationship? How to avoid that this error "Error occurred while trying to read BldFl1Sh (i)(which is in 'BLADE MODE SHAPES')" does not occur? In other words, where can I learn about the relationship between these parameters in the "Blade. dat" file? By the way， I use FASTv8.

[jjonkman]

Dear @Crystal0912,

Again, I can't provide more guidance on your input file processing error without more clarification from you, but you should be able to use the Echo option to debug problems within input file formatting.

I would not expect structural damage to effect the blade mass. It could effect the blade stiffness, but I'm not an expert on what such relationships would be. Perhaps someone else can comment.

Best regards,

[Crystal0912]

Dear @jjonkman,

Thank you for your help. I ran successfully by modifying the parameter "FlpStff and EdgStff". It is really irrelevant to the "BMassDen" parameter, as you said.

Best regards,

[Jafariasl]

Hi @Crystal0912 and @jjonkman
I faced this problem. Can you share the modified values of FlpStff and EdgStff?
Best