Coordinates system conventions for DTU 10MW RWT vs. FAST's coordinates system conventions

Wind & Water Computer-Aided Engineering Software Tools
1

Hi,

I need clarifications about the relationships between coordinates system of DTU 10MW RWT and FAST’s coordinate system.

In particular I’m confused for what concern the pitch rotation: in order to perform correct computation with FAST I need to add the structual twist of the blade (obtained from DTU 10MW RWT structural properties documentation based on HAWC2 computation) in the blade input file required by ElastoDyn with opposite sign respect to the 10MW RWT documentation.

Furthermore, I tryed to implement Bend-Twist Coupling in my simulation using BeamDyn and still considering the DTU 10MW RWT: I selected the coupling coefficient in order to obtain twist-to-feather coupling (according to the papers I considered, which consider DTU 10MW RWT, I must select a coupling coefficient between -0.1 and -0.2 in order to obtain twist-to-feather effect) and the results from FAST simulation were completely wrong: indeed the implemented twist-to-feather BTC increased the thrust on the rotor like what would happen using twist-to-stall BTC. This undesired output from FAST simulation was corrected succesfully simply considering the coupling coeffiecient with opposite sign in the blade input required by BeamDyn.

Please, could you let me know about the relationship, especially on pitch angle, between FAST’s coordinate system and DTU 10MW RWT’s coordinate system?

Thanks in advance for your help.

Simone

2

Dear Simone,

Please see my post dated July 20, 2020 in the following forum topic for a document written by Emmanuel Branlard of NREL that provides guidance for converting HAWC2 blade models to BeamDyn: Simulations using BeamDyn - #6 by Jason.Jonkman.

Best regards,

3

Thank you, your advice was very helpful.

Simone