NREL 5-MW eigenfrequencies

1 Test description

In this load case, we compare the eigenfrequencies of the NREL 5-MW reference wind turbine from Ashes to the results given in the specification document (Table 9.1 in Jonkman et al. (2009k)). 

2 Model

The model is the Onshore NREL 5-MW reference wind turbine, which corresponds to the onshore template in Ashes

3 Results

The eigenfrequences of the model are solved and compared to those from FAST and ADAMS presented in the specification document. Note that the numbering of the eigenfrequencies in Ashes is from the lowest frequency to the highest, which is not the same as in the specification documentt. The table below summarises the numbering correspondance.

Mode number in AshesMode nameMode number in the specification document
11st Tower Side-to-Side2
21st Tower Fore-Aft1
31st Drivetrain Torsion3
41st Blade Asymmetric Flapwise Yaw 4
51st Blade Asymmetric Flapwise Pitch5
61st Blade Collective Flap6
71st Blade Asymmetric Edgewise Pitch7
81st Blade Asymmetric Edgweise Yaw8
92nd Blade Asymmetric Flapwise Yaw9
102nd Blade Asymmetric Flapwise Pitch10
112nd Blade Collective Flap11
122nd Tower Side-to-Side13
132nd Tower Fore-Aft12

A bar plot with the eigenfrequencies from the specification document and from Ashes is available on the following link.

Note that only a visual check is performed here.