IEA 22 MW RWT - AeroDyn vs BeamDyn - No. of Blade Nodes

Wind & Water Structural Analysis
1

Hi, I’ve noticed that the BeamDyn blade only has 30 nodes rather than 59 in AeroDyn & ElastoDyn. How are the loads transferred from AeroDyn to BeamDyn with different blade discretisation? Is this just because the loads are transferred as distributed loads per unit length rather than nodal loads?

------- AERODYN v15.00.* BLADE DEFINITION INPUT FILE -------------------------------------
Generated with AeroElasticSE FAST driver
====== Blade Properties =================================================================
59 NumBlNds - Number of blade nodes used in the analysis (-)

------- BEAMDYN V1.00.* INDIVIDUAL BLADE INPUT FILE --------------------------
Generated with AeroElasticSE FAST driver
---------------------- BLADE PARAMETERS --------------------------------------
30 station_total - Number of blade input stations (-)

Also, when running with CompElast = 2, is any of the blade information within the ElastoDyn_blade file used? Or is this information disregarded and BeamDyn just uses information within BeamDyn main file and blade file?

Thanks,
Barry Britton

2

Dear @Barry.Britton,

In OpenFAST, different modules can have different spatial discretizations and the transfer of inputs / outputs between modules happens through spacial mesh-to-mesh mapping, which occurs within the OpenFAST glue code. The mesh-mapping algorithms are documented here:
https://www.nrel.gov/docs/fy14osti/60742.pdf (original description)
https://dx.doi.org/10.2514/6.2015-1461 (a few updates to the former)

When BeamDyn is enabled with CompElast = 2, the blade-related inputs and outputs in ElastoDyn are unused. This is documented in the FAST v8 ReadMe file, most of which applies to OpenFAST: https://openfast.readthedocs.io/en/main/_downloads/5f2ddf006568adc9b88d8118dc3f1732/FAST8_README.pdf.

Best regards,

3

Dear @Jason.Jonkman,

Great, thanks!