Blade mass imbalance

Discuss the theory and modeling of rotor aerodynamics.

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Organization: the University of Tokyo
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Blade mass imbalance

Postby Shuai.Wang » Sun Jun 17, 2018 11:42 pm

Hi Everyone.

My wind turbine model in FAST has 3 blades. I changed the ‘AdjBlMs’ of blade 1 to 1.01 for setting blade mass imbalance, and saw it clearly affect the tower base moment PSD 1P at across wind direction.

However, I want to change more on 1P and set ‘AdjBlMs’ of blade 2 the same value of 1.01 as well, while kept ‘AdjBlMs’ of blade 3 still as 1. The result of 1P shows the same with my first trying (only set imbalance on 1 blade ), that is out of my expectation.

So I wonder how FAST consider the imbalance? Why change on 1 blade and on 2 blades have the same results?

Thanks in advance.
Shuai Wang

Posts: 5765
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO

Re: Blade mass imbalance

Postby Jason.Jonkman » Mon Jun 18, 2018 3:48 am

Dear Shuai Wang,

I'm not sure what you mean when you say, "[t]he result of 1P shows the same with my first trying". However, your understanding of how to define a rotor-mass imbalance in the ElastoDyn module of FAST is correct. To increase the imbalance, you could further change the mass of one blade; it is also common to make one blade heavier and one blade lighter than the reference blade when setting the mass imbalance.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901

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