Dear jason,
Yes, it works well when i set a value to the PtfmYIner.
However, my following research focus is to explore the impact of marine growth thickness on the structural response of offshore wind turbines. IEA 15MW monopile OWT is selected as the prototype, and the thickness of marine organisms are 25mm,50mm,75mm and 100mm in turn. When i am trying to model the 25mm marine growth, I encountered an error similar to https://forums.nrel.gov/t/modelling-marine-growth-on-5mw-oc3-hywind-spar-errors/2515 described, but unlike the above error, my simulation failed at the beginning. Also, it should be noted that I have set the simulation step size to 0.001s to eliminate instability.
First I will explain the setup I have used, and then secondly the errors I’m seeing as a result.
Marine Growth modelling
So in the HydroDyn.dat input file, I have entered the below:
---------------------- MARINE GROWTH -------------------------------------------
2 NMGDepths - Number of marine-growth depths specified (-)
MGDpth MGThck MGDens
(m) (m) (kg/m^3)
2 0.025 1400
-20 0.025 1400
---------------------- MEMBER OUTPUT LIST --------------------------------------
No changes have been made other than those added above.
Errors Encountered
Running ROSCO-v2.5.0
A wind turbine controller framework for public use in the scientific field
Developed in collaboration: National Renewable Energy Laboratory
Delft University of Technology, The Netherlands
FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption1:FullOpt1_InputOutputSolve:SD_CalcOutput:
Small angle assumption violated in SUBROUTINE SmllRotTrans() due to a large UR_bar input angles.
The solution may be inaccurate. Simulation continuing, but future warnings from SmllRotTrans()
will be suppressed.
Additional debugging message from SUBROUTINE SmllRotTrans():
The BEM solution is being turned off due to low TSR. (TSR = 1.8975). This warning will not be
repeated though the condition may persist. (See GeomPhi output channel.)
FAST_Solution:FAST_AdvanceStates:AD_UpdateStates:BEMT_UpdateStates(node 46, blade
1):UA_UpdateStates:UA_UpdateDiscOtherState:ComputeKelvinChain:Mach number exceeds 1.0. Equations
cannot be evaluated.
OpenFAST encountered an error at simulation time 0.232 of 300 seconds.
Simulation error level: FATAL ERROR
Aborting OpenFAST.
Inexplicably, when I set the marine growth thickness to 50mm,75mm and 100mm, the calculation continued smoothly and work well.
The all simulation files can be found in https://drive.google.com/drive/folders/105IE4ZbeYYAFDrFt3sMfHQMgYAKCZg_A?usp=sharing, hoping you could give me some suggestion.
Best regard,
Yiqi