15MW IEA DLC6.X Analysis result comparison

Wind & Water Computer-Aided Engineering Software Tools
1

Hello NREL Forum Users,

I have conducted an analysis of a floating offshore wind system built with the IEA 15MW Turbine and the VolturnUS-S platform.

The analysis was performed for DLC 6.2 using OpenFAST and OrcaFlex respectively.

The modeling has been fully completed, and upon reviewing the analysis results, the positions of mooring lines with high tension under certain environmental conditions, as well as the motions of the floater, showed similar behavior between the two tools.

However, the maximum mooring tension observed in OpenFAST is significantly lower than that observed in OrcaFlex (approximately 1.5 times lower in OpenFAST).

Could it be that something is wrong with the OpenFAST analysis?

Has anyone else performed an analysis of the IEA 15MW model using other tools and observed similar results to mine?

Or could there be an issue in the analysis process, such as the steps shown in the figure below?

image
image1416×848 48.1 KB

I would appreciate any thoughts or insights.

Sincerely,
Jisu Lim.

2

Dear @Jisu.Lim,

Certainly we’ve compared OpenFAST against OrcaFlex many times, generally with good agreement, but I’m not aware of the specific case were you are comparing.

You mention DLC 6.2, which presumably refers to the storm case of an idling turbine under 50-year wind and wave conditions with large yaw error (due to grid loss). Normally this case is run without BEM and without an unsteady airfoil aerodynamics model enabled; however, I see these mentioned in your screen capture. Can you clarify?

Best regards,