Hi all
In the 5 MW baseline offshore OC3Hywind concept, 17 blade nodes are used for analysis (in “NRELOffshrBsline5MW_AeroDyn.ipt” file )
I am wondering how I can change the number of nodes in the blades. I know I have to use ADAMS to run my simulations.
Thanks
Mahdi Norouzi
Dear Mahdi Norouzi,
The aerodynamic and structural discretization of a blade in FAST, AeroDyn, and FAST-generated ADAMS models is defined by the discretization specified in the AeroDyn input file. See inputs BldNodes, RNodes, and DRNodes in the AeroDyn input file, which are described in the AeroDyn and FAST User Guides. The following forum post provides further guidance on how to define RNodes and DRNodes consistently: viewtopic.php?f=4&t=241.
I’m not sure why you say that “[you] know [you] have to use ADAMS to run [your] simulations.” In many cases, the FAST code–which is far easier to use than ADAMS–can be used to simulate wind turbine dynamics accurately.
I hope that helps.
Best regards,
Dear Jason
In the ADAMS model (OC3Hywind) there are 17 structural sections on each blade. I want to change the number of the structural sections and run my simulations using ADAMS. I do not know how to add new sections to the blades? Adding new sections (elements) to the tower is easy but for the blades it does not seem to be that easy. Should I modify ADAMS data set (*.adm) files manually?
I know the story in FAST is different, MODES is used to obtain the mode shapes of the blades and then mode shapes are used as input to FAST. Changing the number of nodes in the tower or the blades would not change the results of FAST since FAST is not considering number of nodes as an input. I changed the number of nodes in the tower (changing “TwrNodes” in *.fst file) and observed no difference in FAST results (as expected).
Thank you
Mahdi
Dear Mahdi,
As I said in my prior post, the number and location of the structural sections in FAST-generated ADAMS models is determined by inputs BldNodes, RNodes, and DRNodes in the AeroDyn input file. If you want your ADAMS model to have more than 17 sections, increase BldNodes to be more than 17, modify RNodes and DRNodes accordingly, and rerun the FAST-to-ADAMS preprocessor to recreate your ADAMS model.
The number of tower nodes, TwrNodes, and blade nodes, BldNodes, does influence the FAST solution. For structural dynamics, they determine the number of structural elements to be used to integrate the generalized mass and stiffness matrices in FAST. (The more elements, the more accurate the integration.)
Why is it that you need to use ADAMS in place of FAST? The OC3-Hywind system can be modeled in FAST with accurate results.
I hope that helps.
Best regards,
Dear Jason
Thank you so much for your previous post. It helped me to add new elements to my blades.
For Chord and AeroTwst data I did interpolation to get values for my new elements (using data given in *.ipt file). I was wondering which NREL tool I should use to generate Chord and AeroTwst data for my new elements.
Another question:
In your thesis you stated that you had used FAST version 6.10a-jmj and Aerodyn version v12.60i-pjm to run your simulations. The last version I have found in your public domain is version v6.02c-jmj of FAST with Aerodyn v12.58. Is there a big difference between those versions?
Regards
Mahdi
Dear Mahdi,
We at NREL don’t supply any tools for simple spanwise interpolation of aerodynamic data. For this, MS Excel or other general purpose software can be used.
FAST v6.02c-jmj and AeroDyn v12.58 are the latest versions of FAST and AeroDyn that have been publically distributed. FAST v6.10a-jmj and AeroDyn v12.60i-pjm (and newer) contain some new functionality, but are still under development. The new features I used for my thesis were updates to the override control options in FAST and an upwind tower influence model in AeroDyn. We plan to publically release our next versions FAST, AeroDyn, and ADAMS-to-AeroDyn with these (and other new) features about two months for now. Until then, I hope that the present versions are suitable for your purposes.
Best regards,