FSI - rotating domain CFX and mechanical

Monimo · October 19, 2018, 10:29

Hey there,

In the area of FSI I am a very, very beginner and hope somebody can help me

I am trying to set up a bidirectional Fluid Structure Interaction between a wind turbine blade and the outer domain, using rotational and linear velocity. I use a 120° section of the complete turbine (cylindric domain).
Here is the general outline
https://imgur.com/a/DMtK1UL
Now I want to create a set up, where I can simulate the rotation of 0,2 rad/second of the wind turbine and the inlet velocity of fluid domain with 10 m/s.

Here is my coupling
https://imgur.com/Z9dDCip

I am not sure about the areas, where I have to insert the velocitys. Of course I have to insert the normal velocity of stream in CFX, but for the rotation:

- Do I have to give in mechanical the radial velocity for my blade
- Do I have to use the rotating domain in CFX (than for all parts - think so?!)
- Or do I have to change both with the same value?

I am a little confused. Hope somebody can help me!

I Use Ansys 18.1 academic version.

Maybe there is also somebody, who can tell me, how I can create the output of the normal vector of the surface elements.

Greetings Monika

ghorrocks · October 19, 2018, 22:09

It appears you are quite new to CFX, so I recommend not working on the FSI work quite yet. First I recommend you do the CFX tutorials, especially the ones on rotating machinery, fsi and blade flutter. These are available on the ANSYS Customer webpage.

By the way, blade flutter is an alternate approach to this which may work better in your case. That's why you should get a background in blade flutter, fsi and rotating machinery before proceeding so you know what approach will work best.

Monimo · October 20, 2018, 09:49

First of all thank your for reply.

I have done steady state calculations but no FSI until now. So yes, I am beginner, as I already mentioned (I am still student, too).

Unfortunately I have to do this, its no question of will.

I am familiar with the FSI tutorial for the oscillating plate, and know, that tutorials about blade flutter in turbo mashinery are available.
But my colleagues, superiors (and I) act on the assumtion, that the flutter of turbo mashinery has as a cascade flutter an other physical background than airfoils in wind turbines and planes with the bending-torsion flutter. So their assumtion is, that the Transient Blade Row Modus of CFX ist not unimpeachable usefull for this task.

But I will go through the mentioned tutorials again

October 19, 2018, 10:29	FSI - rotating domain CFX and mechanical	#1
Monimo New Member Moni Join Date: Oct 2017 Posts: 3 Rep Power: 9	Hey there, In the area of FSI I am a very, very beginner and hope somebody can help me I am trying to set up a bidirectional Fluid Structure Interaction between a wind turbine blade and the outer domain, using rotational and linear velocity. I use a 120° section of the complete turbine (cylindric domain). Here is the general outline https://imgur.com/a/DMtK1UL Now I want to create a set up, where I can simulate the rotation of 0,2 rad/second of the wind turbine and the inlet velocity of fluid domain with 10 m/s. Here is my coupling https://imgur.com/Z9dDCip I am not sure about the areas, where I have to insert the velocitys. Of course I have to insert the normal velocity of stream in CFX, but for the rotation: - Do I have to give in mechanical the radial velocity for my blade - Do I have to use the rotating domain in CFX (than for all parts - think so?!) - Or do I have to change both with the same value? I am a little confused. Hope somebody can help me! I Use Ansys 18.1 academic version. Maybe there is also somebody, who can tell me, how I can create the output of the normal vector of the surface elements. Greetings Monika

October 19, 2018, 22:09		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	It appears you are quite new to CFX, so I recommend not working on the FSI work quite yet. First I recommend you do the CFX tutorials, especially the ones on rotating machinery, fsi and blade flutter. These are available on the ANSYS Customer webpage. By the way, blade flutter is an alternate approach to this which may work better in your case. That's why you should get a background in blade flutter, fsi and rotating machinery before proceeding so you know what approach will work best. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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October 20, 2018, 09:49		#3
Monimo New Member Moni Join Date: Oct 2017 Posts: 3 Rep Power: 9	First of all thank your for reply. I have done steady state calculations but no FSI until now. So yes, I am beginner, as I already mentioned (I am still student, too). Unfortunately I have to do this, its no question of will. I am familiar with the FSI tutorial for the oscillating plate, and know, that tutorials about blade flutter in turbo mashinery are available. But my colleagues, superiors (and I) act on the assumtion, that the flutter of turbo mashinery has as a cascade flutter an other physical background than airfoils in wind turbines and planes with the bending-torsion flutter. So their assumtion is, that the Transient Blade Row Modus of CFX ist not unimpeachable usefull for this task. But I will go through the mentioned tutorials again