Open 126qoq opened 7 months ago
Dear @126qoq,
Here are my responses:
Best regards,
Dear Dr. Jonkman,
Thank you for your answer. I didn't actually do the linearization.The tower natural frequencies through linearization are my quotes from other people's calculations: https://forums.nrel.gov/t/the-frequency-component-of-flapwise/1730/4 Actually, I'm more interested in figuring out if my calculations via FFT make sense or not.
Best regards,
Dear @126qoq,
The preferred way to calculate the full-system natural frequencies is through an OpenFAST linearization analysis. I suggest using that to verify your estimation of natural frequencies through FFT.
Best regards,
Dear Dr. Jonkman,
I am now working om the Test 25 of the NREL 5 MW-OC4-DeepCwind SemiSubmersible wind turbine. I designed two models, one is a normal operation floating wind turbine model, and for the other one all six platform degrees was disabled. The wind speed was set to be the rated wind speed in turbulent wind, and the waves were irregular waves of 6 m, 10 s. FFT analysis of the tower top acceleration of the two models was carried out. I found that the first-order natural frequency of the tower appeared was 0.463 Hz for the normal model and 0.405 Hz for the constraints, as shown in Fig. 1. The FFT analysis of the acceleration in the SS direction shows 0.442 Hz for the normal model and 0.376 Hz for the constraints, as shown in Fig. 2. Here are my questions.
Best regards, Yao Ge