Issue with Tower Load Calculation in OpenFAST

Dear all,

I am currently working on calculating the tower loads on the main structure and encountered an issue. I noticed that the tower is divided into 9 sections, and it is possible to retrieve local loads for each section. To do this, I added the relevant output channels in the ElastoDyn file.

However, when I ran the simulation, the values for these channels were set to 0, and no units were provided, which suggests that the loads were not computed.

Upon reviewing the ElastoDyn file, I saw that the NTwGages parameter was set to 0. I updated this to 9 and attempted the simulation again. Unfortunately, I received the following error:

Error reported by S-function ‘FAST_SFunc’ in ‘Paper_P01_sim/FAST Nonlinear Wind Turbine1/S-Function’:
FAST_InitializeAll:ED_Init:ED_ReadInput:ReadPrimaryFile:Invalid numerical input for file
“.\NRELOffshrBsline5MW_Onshore_ElastoDyn.dat” occurred while trying to read TwrGagNd.

It seems the error is related to how the TwrGagNd parameter is written in the file (see the attached figure). I have read the documentation but unfortunately, I’m not really sure what TwrGagNd refers to or what values I should input for this parameter.

Could you please provide guidance on what the TwrGagNd parameter represents and what the correct values should be in this case?

Best regards,
Sarah Gilles

Dear @Sarah.Gilles,

TwrGagNd specifies the list of nodes you want to place the gages at. If NTwGages = 9, you should specify 9 values in this list (in your case, you’ve set NTwGages = 9 but only list 3 values of TwrGagNd, hence the error). Each value should be between 1 and TwrNodes, where 1 is the lowest node and TwrNodes is the highest.

Best regards,

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