How to setup BeamDyn Standalone.

[Jamie7963]

Hi.

I wanted to know more about using beamdyn as a standalone module and I wanted to check through some things with you guys to check that I understand the input files correctly and then subsequently reading the outputs correctly.

I have read through the manual and the outputs on the online readthedocs page and also the manuals. I'm still not 100% certain that I am doing this correctly as I couldn't find much about running it stand alone.

For my driver file, is this correct:

where Gz is the global vertical direction
GlbPos(3) is the hub radius
I understand the initial blade root frame should also probably contain the precone too, but if just including the pitch angle would this be correct
then for the root velocity parameter it would just be RootVel(4)=turbine_revolutions_per_second

---------------------- GRAVITY PARAMETER --------------------------------------
0 Gx - Component of gravity vector along X direction (m/s^2)
0 Gy - Component of gravity vector along Y direction (m/s^2)
-9.8 Gz - Component of gravity vector along Z direction (m/s^2)
---------------------- FRAME PARAMETER --------------------------------------
0 GlbPos(1) - Component of position vector of the reference blade frame along X direction (m)
0 GlbPos(2) - Component of position vector of the reference blade frame along Y direction (m)
hub_radius GlbPos(3) - Component of position vector of the reference blade frame along Z direction (m)
---The following 3 by 3 matrix is the direction cosine matirx ,GlbDCM(3,3),
---relates global frame to the initial blade root frame
cos(pitch_angle) -sin(pitch_angle) 0
sin(pitch_angle) cos(pitch_angle) 0
0 0 1
T GlbRotBladeT0 - Reference orientation for BeamDyn calculations is aligned with initial blade root?
---------------------- ROOT VELOCITY PARAMETER ----------------------------------
{turbine_revolutions_per_second} RootVel(4) - Component of angular velocity vector of the beam root about X axis (rad/s)
0 RootVel(5) - Component of angular velocity vector of the beam root about Y axis (rad/s)
0 RootVel(6) - Component of angular velocity vector of the beam root about Z axis (rad/s)
---------------------- APPLIED FORCE ----------------------------------

for my primary file:
twist_degrees starts as the twist at the root (i.e the maximum twist value). For example, 20, 19, 18, 17, etc.
reference_axis_x - blade reference axis with x as the thicknesswise direction
reference_axis_y - blade reference axis with y as the chordwise direction
reference_axis_z - blade reference axis with z as the z axis towards the blade tip direction

---------------------- GEOMETRY PARAMETER --------------------------------------
1 member_total - Total number of members (-)
{number_of_stations} kp_total - Total number of key points (-) [must be at least 3]
1 {number_of_stations} - Member number; Number of key points in this member
kp_xr kp_yr kp_zr initial_twist
(m) (m) (m) (deg)
{reference_axis_x} {reference_axis_y} {reference_axis_z} {twist_degrees}

[jjonkman]

Dear @Jamie7963,

Yes, your understanding is correct.

For your pitch_angle, I assume you are following IEC convention where positive pitch is defined about the negative z axis (just like the initial_twist is), for the z (pitch axis) pointed from the root to the tip.

Best regards,

[jjonkman]

Dear @Jamie7963,

These BeamDyn rotational outputs are unitless, as they are expresed as Wiener-Milenkovic parameters. See their definition in the BeamDyn documentation: https://openfast.readthedocs.io/en/main/source/user/beamdyn/theory.html#wiener-milenkovic-rotation-parameter. You could convert these to other rotational parameters in a post-processing step.

Best regards,

[Jamie7963]

Had a question on BeamDyn results. My tip node values look a bit weird. I have 100 key points, the absolute positions of point 99 and point 100 are exactly the same and the resultant forces are quite high for point 100. I'm a bit lost as to why this is. I have run two simulations with slightly different stiffness and mass matrix values for the tip and both produce the same result. First was values as expected, second was to modify point 100 values to equal point 99 values to see if it was a problem with my values. Am I using BeamDyn wrongly here or is something else going on?

[jjonkman]

Dear @Jamie7963,

Can you clarify which outputs you are using and what you are actually seeing in the results?

You mention kp_total = 100, but what have you set quadrature and order_elem to?

Best regards,

[Jamie7963]

I hope the graphs are clear, essentially the absolute positions of the final two nodes are equal, even though, the position of the final two nodes is:

0.0 0.0 43.55555555555556
0.0 0.0 44.0

quadrature = 2
order_elem = 5

[jjonkman]

Dear @Jamie7963,

With quadrature = 2 in BeamDyn, the nodal outputs will take place at the blade stations defined in the BeamDyn blade input file (as well as in between blade stations if refine > 1), not at the key points. What do you have station_total and refine set to, and what are the station location values at the last few stations?

Best regards,