Hi all,

I have study the test26 (NREL5 MW) from the FAST archive. Now, I would like to try a new blade for my project.

I am wondering how to create a BeamDyn blade input (Sectional stiffness matrix and mass matrix) like the one in the test26. Note that the mY_cm, mX_cm, i_cp are zeros in the test26 BeamDyn blade input mass matrix. I will investigate why these variables are zeros.

I would like to know what software or tool can help me construct these sectional stiffness matrix and mass matrix. So far, I saw some response from the forum that some people uses VABS. Just want to make sure if that is the best tool for creating BeamDyn blade input file.

Thank you!

Dear Daniel,

VABS is popular in the rotorcraft industry and is the one we’ve used at NREL. Other sectional-analysis tools that can derive the full 6x6 cross-sectional mass and stiffness matrices for use in BeamDyn include NuMAD/BPE from Sandia National Laboratory and BECAS from DTU Wind Energy.

Best regards,

Dear Jason,

Thank you for the answer. I will study into those tools. I am also wonder that are they able to generate AeroDyn Blade input? If not, should I manually create the file or there is other tool that does it.

Thank you again.

Dear Daniel,

We don’t currently have a preprocessor that will generate an AeroDyn blade input file; we’ve generated these manually to-date.

Best regards,

Dear Jason,

I am trying to create BeamDyn blade files for Sandia 13.2MW wind-turbine blades (SNL100-00, SNL100-01, SNL100-02, and SNL100-03) since the website only provide blade data for ElastoDyn blade file. Please let me know if the BeamDyn blade files for the Sandia blades are actually available.

I just want to verify that using NuMAD/BPE requires ANSYS to generate BeamDyn blade input file (6x6 stiffness matrices). The reason I asked is because the NuMAD sent out an error that requested path to ANSYS.exe when I tried to create one from its NuMAD model.

I will looking into the BECAS from DTU. I am wondering does BECAS require ANSYSY as well?

Thank you so much for your help.

Dear Daniel,

I’m not familiar enough with the Sandia 13.2-MW blades to know if the 6x6 sectional mass and stiffness matrices are available. I’m also not aware of BeamDyn models that have been made for these blades. I suggest you contact the corresponding authors if the documentation is unclear.

Yes, NuMAD/BPE are pre- and post-processors for ANSYS; ANSYS is required to run the NuMAD/BPE analysis.

BECAS is a standalone tool from DTU Wind Energy, which doesn’t require ANSYS.

Best regards,

Dear Dr. Jonkman,

I am trying to use NuMAD/BPE to create Sandia SNL100 series blade for BeamDyn inputs. However, the NuMAD/BPE stop working after the ANSYS FEA. I have double checked that I followed the manual exactly and all the configurations are correct. I could not resolve this issue.

I emailed the NuMAD team about this issue one week ago and received no feedback. So, I am wondering that have you encounter this issue before? Is the NREL 5MW BeamDyn blade input file created by NuMAD/BPE or VABS? Please advise me on how to get support from NuMAD team.

I understand this forum only support FAST and NREL codes, and I want to apologize for asking questions on NuMAD. It is only because I have not receive any feedback from them, and Sandia blade BeamDyn input model is one of objectives in my graduate thesis.

Thank you.

Dear Daniel,

I’m sorry, but I have little direct experience with NuMAD/BPE and cannot be of help in solving problems related to those tools. Neither can I comment on how the NuMAD team offers support.

The NREL 5-MW BeamDyn blade model was not formed using NuMAD/BPE, VABS or other sectional-analysis tools. Instead, the model is based directly on the beam properties specified for the NREL 5-MW baseline blade: nrel.gov/docs/fy09osti/38060.pdf.

Best regards,

Dear Dr. Jonkman,

Thank you so much for your input. Now, I am able to re-construct NREL 5MW BeamDyn blade input file based on Table 2-1 from the paper you post. However, I have some questions on the stiffness and mass matrices in the NREL 5MW eaxmple.

For Stiffness matrices,

K_ShrFlp = K_ShrEdg = EA/10 for each station. I am wondering how these two value being derived and is this relation consistent for other blade?

For Mass/Inertia matrices,

mX_cm, mY_cm, and i_cp are equal to zero. According to the BeamDyn Manual, “Xcm and Ycm are the local coordinates of the sectional center of mass”,and “icp is the sectional cross-product of inertia per unit span”.

So, by assigning mX_cm, mY_cm, and i_cp equal to zero, it means that the blade reference axis is the same as the sectional center of mass?

Please correct me if I am wrong.

Again, thank you for the helps.

Dear Daniel,

Regarding K_ShrFlp and K_ShrEdg, I’m not sure. The flapwise and edgewise shear stiffness were never defined for the NREL 5-MW baseline blade. Qi Wang (the lead developer of BeamDyn who has now departed NREL) assembled this BeamDyn model and set those values. I would expect the shear stiffness to have a negligible response for this blade (due to the high aspect ratio and lack of bend-twist coupling), so my guess is, Qi set values that had a negligible effect on the response and did not cause numerical problems (being too high or low).

Regarding m*X_cm, m*Y_cm, and i_cp, “yes.” But actually, m*Y_cm is zero in the BeamDyn input file of the NREL 5-MW baseline turbine in Test #26 of the FAST CertTest, but is nonzero in the BeamDyn input file of the NREL 5-MW baseline blade in the BeamDyn CertTest. The former was set so as to better compare the results of Test #26 (with BeamDyn) with Test #18 (without BeamDyn) in an “apples-to-apples” fashion. The latter better matches the data defined in the NREL 5-MW specifications report. i_cp is zero in the NREL 5-MW specifications report because the orientation of the principle axes of inertia are not defined separately from the orientation of the principle axes of bending (and so, are assumed to be coincident).

I hope that helps.

Best regards,

Hi NREAL team,

I am trying to Run Test26 by adjusting a new data for _Beamdyn.dat and BeamDyn_blade.dat. I then updated the_Aerodyn15.dat, _Aerodyn_blade.dat and Elastodyn_blades.dat. I also set windtype=1, HWindspeed=11.4m/s in _inflow.dat. this case just works when I set on CompElast=1, when I set to 2 appears an error as attachment snapshot.

the second question is related to Bend-Twist Coupling terms in 6x6 stiffness matrix in _BeamDyn_blade.dat . which terms in both stiffness and mass matrices should be nonzero in this issue?

Thank you in advance for your help and clarification.

Dear Tohid,

Can I assume the PIDVar screen messages are something that you’ve set in your user-defined controller?

If the Mach number at a blade node is exceeding 1.0, I would expect that the model is suffering some sort of numerical instability. My guess is the blade velocities and deflections are also unrealistically large.

Without knowing what you changed in the BeamDyn model or controller, it is hard for me to guess what is causing the numerical instability. Perhaps you increased the stiffness without dropping the time steps?

By bend-twist coupling, I assume that you mean some sort of composite-material-based coupling between flapwise bending and torsion. In this case, you would set the (5,6) and (6,5) elements of the sectional stiffness matrix to be nonzero.

Best regards,

Dear Jason,

Thanks for your quick reply.

I just modified distributed properties and geometry parameters in Beamdyn input files.

while I am running DTU 10MW RWT turbine, I set servodyn input according performance of this turbine. to knowing more detail about PIDVar of this turbine, I refer to look this link : dtuwindenergy.github.io/BasicDTU … controller

my screen message from servodyn input file are:

Best Regards,

Tohid.

Dear Tohid,

That all sounds fine. My guess is that something in your change to the distributed and/or geometry properties of the BeamDyn model is the source of the problem.

Best regards,

Dear Dr. Jonkman,

Thank you for your time.

I checked and compared the Distributed and geometry of BeamDyn model with Test26. it seems they have considered EA=K_edg=K_flap. why didn’t used the real data? while K_edg stiffer than K_flap, it then should be biger.

I created according Test26 Beamdyn blade format. but still error remained by another type of BEMT problem while this run in CompElast=1 condition.

If you get some time, I would like to request your help.

Thanks,

Tohid.

Dear Tohid,

The reason for EA = K_ShrFlp = K_ShrEdg for the BeamDyn input files supplied by NREL for the NREL 5-MW baseline turbine is discussed in my post dated Oct 27, 2016 in the following forum topic: http://forums.nrel.gov/t/creating-beamdyn-blade-input/1325/10.

I’m assuming you mean that your model goes unstable with CompElast=2, but not CompElast=1.

I see in your results that Vy is very large and Vx is very large and negative-valued, which are unphysical values. This suggests to me that your model is going numerically unstable for some reason. Again, I would expect a problem in your BeamDyn model. I suggest that you debug by first verifying that your BeamDyn model works well in standalone BeamDyn (e.g. solves properly and yields the expected force-displacement relationships for applied tip loads).

Best regards,

Dear Jason,

I adjusted my BeamDyn blade input file. I first ran my model in standalone BeamDyn and worked well. now I coupled BeamDyn and FAST. I also updated source code of AeroDyn based on the link https://github.com/NWTC/AeroDyn and discussion in [url]Problem running Test18.fst in Simulink by Changing TMax using FAST_8.16 - #4 by Jason.Jonkman]. using of {AFAeroMod=2,TwrPotent=0,SkewMod=2, UAMod=3 } in AeroDyn 15 and WindType=1 in inflowWind, the BEMT problem still remained (see BEMT_Error.jpg).

by setting airfoil aerodynamic model to steady model, negative Vx problem appears (see BEMT_Error2.jpg).

please do you have some idea about this new issue?

Best regards,

Dear Tohid,

It doesn’t appear that you’ve updated AeroDyn to v15.04 because in AeroDyn v15.04, it is not possible to trigger an error regarding “no valid value of phi”. I would start by recompiling FAST v8 with AeroDyn v15.04 available from: github.com/NWTC/AeroDyn.

Best regards,

Dear Jason,

Thank you for your support here.

finally I could recompile FASTv8.16 with AeroDyn 15.04 in Double precision. I then ran my case, unfortunately faced with new error.

My research area is more focusing on the blade aero-elasticity. this is why I try to use FAST-BeamDyn coupling.

Could you point me to the right procedure if I have wrong?

Best regards,

Tohid.

Dear Tohid,

Again, it doesn’t appear that you’ve updated AeroDyn to v15.04 because in AeroDyn v15.04, it is not possible to trigger an error regarding “no valid value of phi”.

Best regards,