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How to define a DLC load case in QBlade-CE?
Hi Jianxu,
upon first glance your calculation seems to be sound.
I cant tell you exactly where these differences are coming from. They could be caused by different controller parameters, a different structural blade setup or differences in the ECD files used.
But be aware that several revisions of the IEA15MW turbine, including the structural blade definition, have been published over the past years, see:
https://github.com/IEAWindSystems/IEA-15-240-RWT
The model in QBlade is mostly based on v 1.1.6 of the IEA 15MW turbine. The structural blade data table is converted from the HAWC2 structural data table found here:
The original report is from 2020, so some of these results might actually be outdated.
I would suggest to try looking for the most recent data available to do this comparison, or maybe event try comparing directly to an OpenFAST model for which you know that the model definition is consistent with the QBlade model.
BR,
David
Hi David,
Thank you for your patient reply. I’m looking into the links you provided above and meanwhile I’m looking for a quick check if possible.
If you can kindly provide me a valid DLC 1.4 wind input file (.wnd) for this IEA 15MW 240 RWT with 150m hub height? In this case, I may quick check step-by-step to locate where the problem is (wind/contols/blade model/etc.).
Thank you in advance and appreciate for your professional help.
Best regards,
Jianxu
Hi Jianxu,
you can generate the ECD hub-height wind files required for DLC 1.4 using the IECWind tool, which is available for download from the NREL website:
https://http://www.nrel.gov/wind/nwtc/iecwind
The generated files can then be directly imported into QBlade.
BR,
David
Thank you David. I have already tried IECWind to generate .wnd file as input for DLC 1.4 followed your guidance about 2 weeks before (see our disscussion history). However the load gap between Qblade calcuated and reported based on the IEA 15MW RWT was still there. That’s the reason I would ask help here if you can kindly provide a DLC 1.4 .wnd file from your side to check if my QBlade calcuated load would be the same as the reported value. In this case, I can locate the issue for my software chain (IECWind/QBlade/…) one-by-one.
Appreciate for your kind help.
Best regards,
Jianxu
Hi Jianxu,
the DLC 1.4 Extreme Coherent Gust (ECD) wind field is unambiguously prescribed by the IEC standard. The IEC Wind-Input tool replicates that definition exactly, and QBlade uses the same formulas, so the wind file itself is almost certainly not the source of the discrepancies you’re seeing.
More likely causes include:
Controller parameters
Initial turbine states (yaw misalignment, rotor speed, pitch offsets, etc.)
Blade structural model — a fully populated 6 × 6 stiffness matrix versus a diagonalised approximation
To pinpoint the issue, start with a very simple benchmark in both codes and compare the results step by step. Carefully matching every modelling assumption and input parameter usually reveals where the two solutions diverge.
From experience, the key to a reliable comparison is to document every aspect of the reference model: controller gains, initial yaw angle, blade-stiffness matrices, and so on. In a tightly coupled aero-servo-elastic simulation, even a small difference can lead to noticeably different load responses .
BR,
David
