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IEAWindTask37 / IEA-15-240-RWT

15MW reference wind turbine repository developed in conjunction with IEA Wind
Apache License 2.0
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Statespace and convolution integral method for radiation do not match #102

Closed maxsirigu closed 1 year ago

maxsirigu commented 1 year ago

good afternoon, I am analysing the floating platform Volturn US and the 15 MW reference wind turbine on OpenFAST. I found that the radiation-damping forces change if I simulate the convolution integral or the state-space approximation in a Free-decay test with the rotor spinning (so taking the gyroscopic forces) but with CompAero=false, CompServo=false. I am using the same hydrodynamic data as you can find on Github. The problem is dramatic in surge and yaw, but in roll, pitch, and heave the results are similar. Have you already noticed this problem? thank you in advance, Massimo Sirigu

jjonkman commented 1 year ago

Dear @maxsirigu,

It looks like you asked a similar question on the NREL forum (https://forums.nrel.gov/t/hydrodynamic-implementation/2284/63), where I suggested that the solution is likely to improve the fit of the state-space model.

Best regards,

maxsirigu commented 1 year ago

Hello, yes, I wanted to contact the developers of the Volturn US platform and so who realised the state space configuration. Fortunately, I found the time step was the problem: From a timestep of 0.05 seconds, I had to put 0.01 seconds to fit the curves. Kind regards, Massimo