[Antanas]

Originally Posted by shIxx

Hi all,

I tryed the steps from GeorgD´s post above and I hope that I have done it right.
But it dont seem to be the case, because the result looks confusing.
Well, at least ther is a result.

Update:
A detailed descrition of what I did:
1.) Import the model with 2 bodies (stator + rotor)
2.) Created an enclosure (rotating_enclosure) that covers the model.
3.) Created a boolean and substracted the rotor from the rotating_enclosure.
4.) Created a second enclosure (static_enclosure) wich represents the air-zone.
5.) Createt a second boolean and substracted the stator and the rotating_enclosure.
6.) Supressed the stator and the rotor in the bodie tree.
7.) Created the name selections outlet_1, outlet_2 and wall

I uploadet a new video. Link:
https://youtu.be/NCr8CLaT8mM

It seems that the inner (rotating) enclosure is a like a invisible wall, but it isnt defined as wall, as seen in the video.
Because the inner_enclosure includes the stator, it seems that the stator is also rotating. So first I treyed with the sketcher to draw a circle between stator and rotor an extruded it. but then I got this Error:
"Divergence detected in AMG solver: pressure correction"
Maby I shoud create another boolean between the steps 5 and 6 to add the stator again to the static_enclosure.... Ok the stator is rotating, or not... no matter at the moment.

There must be another mistake on the boundery conditions or the cell zones.

@Ahmed: Thanks for the tip about theory user guide, I will read and try some examples.

@GeorgD: A steady simulation is really a time saver,.. thanks. But if I run a steady simulation, there are no results about the velocity, because in this case there is no inlet and at the time t=0s the air is not moving. For the pressure its Ok.

Thanks for your efforts,
Tom

Share your project

[GeorgD]

Hi Thomas,

Your mesh setup seems to be correct. Its hard to tell what is causing your remaining issue based on your video.
It would be great if you could sent a video of the velocity contour in the xz plane (or your setup)

From what you said, I assume that the interface is not working correctly. Maybe the meshing tool fails to create a correct contact zone.
Try this:
- First: Get rid of the stator for now. To make sure that it does not cause any error. You can re implement it if the fan is working.
- in Fluent, delete the interface and re-define it manually. Ensure that only the mantle of the inner enclosure and the corresponding surfaces of the cylindric hole in the outer enclosure are included in the interface. Also ensure that there is no overlap between both enclosures.

Regarding the rotating stator: If the stator (or more precise the stator shaped gap) is inside inner enclosure it will rotate along with the fan (because you defined this part as rotating). Try to make the inner enclosures radius smaller so that its mantle is inbetween the maximum fan radius and the minimum stator radius. Throug this, the stator will be part of the outer enclosure (which is not rotating)

Greetings
Georg

Sent from my SM-G920F using CFD Online Forum mobile app

[shIxx]

Hi all,

Share your project

Is everything includet in the .wbpj file or something else needs to be shared?

First: Get rid of the stator for now.

Try to follow eng Raef bolean methods

I will do it this way. I´m shure it will work becaus it is exactly the same situation as shown in the tutorial then.
Pity, so the whole learning effect is lost, because I wold like to learn to use fluent with several objekts. And as I sayd in an earlier post, this exersice shold only be the first step. Later I would like to try what happens, if the fan is for example 100°C and how the heat is transfered by the air into the environment and perhaps against a pipe in wich water fows (or against a wall made out of aluminium) for example.
However,... I will report.
Question: is it enough to suppress the stator in the DM or does the CAD model have to be changed?

Off topic:
Btw this example would be a great idea for a tutorial. If someone could explain such a situation (or something similar) easily understandable,
it would certainly help many people, in my opinion. Seperated in parts. For example:
1.part: fan is rotating like this tuturial we talk about (with stator).
2.part: Heat tranfer from the hot fan.
3.part: hot air against a wall.
just an idea

Greetings,
Tom

[Ahmed Saeed Mansour]

Dear Thomas, any simulation by fluent, try to import only the parts that you will use them for the simulation, if the stator you talk about will not be used ...cancel it before importing the geometry into ansys...I may carry out a 3D tutorial about sliding mesh technique but on a VAWT with the same airfoil that I used in the my 2D tutorial...Then we may complete the heat transfer part if possible and you can apply the settings on your fan because the idea will be the sam and you can change the model ...but I may upload this tutorial in the near future due to my tasks...
Thanks

[Antanas]

Originally Posted by shIxx

Hi all,
Is everything includet in the .wbpj file or something else needs to be shared?

Yes. You may pack your project to .wbpz archive (File -> Archive) and share it.

[shIxx]

Here the Project File
https://drive.google.com/file/d/0B9M...ew?usp=sharing

I think the problem is my model bcause it works fine with the Step file from the tutorial.

[Ahmed Saeed Mansour]

Dear Thomas, do you have a problem now?
Thanks

[shIxx]

Dear Ahmed,
I have not been able to do this simulation successfully with my model.
It is probably due to the model itself. Anyway, I'm not trying it any further.

But if you have found a solution, please let me know.

[Ahmed Saeed Mansour]

Dear Thomas, I will tell you after getting the solution, it seems that it is a global issue....Don't worry sir.
Thanks

[Antanas]

I played with your project, take a look:

http://dropmefiles.com/igd5g

[shIxx]

Hi Antanas,
i do not know what you've done exactly but it looks like you did it as described in the theory guide and not as shown on the video tutorial.
And your method is for me more understandable.

However, the sulution does not seem to be right because the velocity becomes less and less. I made a short video of the solution.

Thank you all for the effort!

[FaSe]

Hi all
I am simulating a 3D VAWT (Vertical Axis Wind Turbine). I create my geometry and mesh with Gambit as follow: 1) creating 3D model of airfoils. 2) creating an enclosure (cylinder) around the airfoils. 3) creating a box for the entire flow domain. (second enclosure)
In Fluent, i define 3 interfaces. 2 circle faces of inner cylinder and 1 side face of inner cylinder. But after defining interfaces, there are two walls defined for each interface automatically in boundary conditions tab. what is the reason? and what should i do with these walls? they are automatically set to stationary walls.

Thanks.

[Ahmed Saeed Mansour]

Originally Posted by FaSe

Hi all
I am simulating a 3D VAWT (Vertical Axis Wind Turbine). I create my geometry and mesh with Gambit as follow: 1) creating 3D model of airfoils. 2) creating an enclosure (cylinder) around the airfoils. 3) creating a box for the entire flow domain. (second enclosure)
In Fluent, i define 3 interfaces. 2 circle faces of inner cylinder and 1 side face of inner cylinder. But after defining interfaces, there are two walls defined for each interface automatically in boundary conditions tab. what is the reason? and what should i do with these walls? they are automatically set to stationary walls.

Thanks.

Hello, watch this please and tell me if you still have a problem..Thanks
https://www.youtube.com/watch?v=1pA_yk2a4po

[FaSe]

Thank you Ahmed
That is a good video for learning but it didn't show the boundary conditions after defining interfaces. my problem is this:
After defining interfaces, two walls are created automatically for each interface. when i go to Display-->Grid tab and select these walls, there is nothing to be shown.
What should i do about these walls? (They are automatically set to stationary walls).

Best regards.

[Ahmed Saeed Mansour]

Dear Fase, In fluent, the interfaces are automatically detected and we do not do anything to them in the boundary conditions..Try to not to define the interfaces manually and let the solver detect them as I have shown...If you do not get a solution after this, select the interfaces in the boundary conditions and change Wall to interface...then you have to define the interfaces manually in the mesh interfaces tab...Tell me the progress please..Also you can try to carry out the simulation in Ansys like the video to avoid any problem...Thanks

[Ahmed Saeed Mansour]

I defined the interfaces in the tutorial but this is not important because as I said, If you do not define them, they will be automatically detected and no action is needed...

[FaSe]

Thank you Ahmed, your video was very useful.
I did nothing about the walls and everything was OK. If possible please help me with this issue:
How can i simulate VAWT and let the wind to rotate the turbine? I mean that wind itself rotate the turbine instead of defining a constant rotational speed for rotating zone.

Best regards.

[Ahmed Saeed Mansour]

Originally Posted by FaSe

Thank you Ahmed, your video was very useful.
I did nothing about the walls and everything was OK. If possible please help me with this issue:
How can i simulate VAWT and let the wind to rotate the turbine? I mean that wind itself rotate the turbine instead of defining a constant rotational speed for rotating zone.

Best regards.

Not at all dear FaSe , I think We have to write a simple code to make the velocity at inlet variable velocity and then the rotating speed changes with it and with time...I am working on running the simulation like this for variable speed turbines and if I get useful results, I will record the tutorial ..Thanks