[aja1345]

Hi,

I am simulating an known as , using CFX as a solver.

This turbine have 8 blades((360/8)=45 deg=pitch angle). Due to the circumferential symmetry, only one eight of the annulus has been computed, imposing periodic boundary conditions (periodic rotational) in the tangential direction. The computational domain has been restricted in the axial direction to four chord lengths upstream and six chord lengths downstream of the blade.






Computational domain is as follows:






Also, these are set with specified e. Reference pressure is 1 atm. At the inlet I input a normal speed and at the outlet I have Static Pressure SST as turbulence model setting advanced turbulence controls such as curvature correction and production limiter. Frozen rotor interfaces connect the domains. Rotation domain rotates wit and No-slip boundary conditions are imposed on blade and hub and casing in stationary and rotation domain. and also Rotation domain is set as follows





Also, the values of production limiter and curvature correction and conservation target are default values and


My problem is as follows, there is an error in end of set up in CFX.




Also, Set up of passages in 360 is as follows:




I am grateful that guide me about above cases.

Thanks.

Best.

Aja

[aja1345]

About periodic rotational, Is the set up of mesh connection correct?

[aja1345]

[ghorrocks]

There are several people asking similar questions on this. Do you all have the same university assignment or something?

This model can be done in a single rotating frame of reference. Based on the geometry you showed there is no need for a stationary domain or interfaces. This simplifies the simulation considerably.

[aja1345]

Originally Posted by ghorrocks

There are several people asking similar questions on this. Do you all have the same university assignment or something?

This model can be done in a single rotating frame of reference. Based on the geometry you showed there is no need for a stationary domain or interfaces. This simplifies the simulation considerably.

I studied all these questions but I can't solve my problem.

There are many paper and thesis that these create different domains and interfaces because there is not the relative velocity in inlet domain and outlet domain . Is my statement correct?

Do you have any suggestions about error?

Thanks.

Best.

Aja

[aja1345]

Hi,

Preview option don't work for me! why?

Also, specified numbers are wrote in Persian not English! why? I changed keyboard language to English, but still numbers are wrote in Persian! Maybe, it is reason for my problem! and in other words, CFX don't understand these numbers!

[aja1345]

Can no-one guide about the mentioned error?

[-Maxim-]

Originally Posted by aja1345

Also, specified numbers are wrote in Persian not English! why? I changed keyboard language to English, but still numbers are wrote in Persian! Maybe, it is reason for my problem! and in other words, CFX don't understand these numbers!

that might be a problem... try setting the language in Ansys again and in windows. maybe call your ansys rep about that.

I usually do my calculations in 360 degrees but when I set up periodicity, the region lists are called PER1 and PER2 for interface Side 1 and interface Side 2, respectively. Yours are called 'periodic1' and 'periodic1.1'. Double check if that's correct...

[aja1345]

Originally Posted by -Maxim-

that might be a problem... try setting the language in Ansys again and in windows. maybe call your ansys rep about that.

I usually do my calculations in 360 degrees but when I set up periodicity, the region lists are called PER1 and PER2 for interface Side 1 and interface Side 2, respectively. Yours are called 'periodic1' and 'periodic1.1'. Double check if that's correct...

Thanks for your answer,

How do i set language in Ansys?

About periodic BC, I created periodic surfaces with names of periodic1 and periodic1.1 in Gambit. Is there any problem about this work?

I am grateful that guide me more.

Thanks.

Best.

Aja

[-Maxim-]

Tools - Options - Regional and Language Options - English.

I haven't used Gambit yet. I don't know if something is wrong there.

Also in your screenshots, the interfaces look a bit strange. And it seems that there's solid material at the leading and trailing edge of the blades (green colored)?
There are other people here in this forum with exactly the same setup - why don't you meet up with them? (I assume you are in the same class...)

[aja1345]

Originally Posted by -Maxim-

Tools - Options - Regional and Language Options - English.

I haven't used Gambit yet. I don't know if something is wrong there.

Also in your screenshots, the interfaces look a bit strange. And it seems that there's solid material at the leading and trailing edge of the blades (green colored)?
There are other people here in this forum with exactly the same setup - why don't you meet up with them? (I assume you are in the same class...)

Thanks.

Also, I am new in CFX.

Material is air 25 c. there is air 25 c in rotary an stationary domains. why do you say that there is solid material? Can you explain me more about this?

here, interface 1 and interface1.1 are exactly overlap and also, interface2 and interface2.2 are overlap. Is there adjustment about overlap interfaces?
These people are in other universities. And i sent a private message. But they don't answer.

Thanks.

[-Maxim-]

Originally Posted by aja1345

this looks like your blade (solid) has more solid at the leading and trailing edge. Or is that a very fine mesh?
Have you tried to set it up in a single rotating frame of reference? It will save your the struggle with interfaces..
If you really want to do something with interfaces, maybe do some more tutorials about that

[aja1345]

Originally Posted by -Maxim-

this looks like your blade (solid) has more solid at the leading and trailing edge. Or is that a very fine mesh?
Have you tried to set it up in a single rotating frame of reference? It will save your the struggle with interfaces..
If you really want to do something with interfaces, maybe do some more tutorials about that

Originally Posted by -Maxim-

this looks like your blade (solid) has more solid at the leading and trailing edge. Or is that a very fine mesh?
Have you tried to set it up in a single rotating frame of reference? It will save your the struggle with interfaces..
If you really want to do something with interfaces, maybe do some more tutorials about that

I already had tried that distance between interfaces and blade be minimum. but however, i changed CFD model as follows:



No, I am modeling this turbine by using multiple reference frame, in other words, there are stationary and rotation domains.

Yes...but i almost studied related tutorials.

I think that set up of CFX is not correct in some parts, in particularly, about overlap interfaces.

[ghorrocks]

My post #4 explains what you need to do to get this working.

There are many paper and thesis that these create different domains and interfaces because there is not the relative velocity in inlet domain and outlet domain . Is my statement correct?

If you have stationary components and rotating components then you need to put them in stationary or rotating domains and link them with GGIs. But in this case you only have a rotating component so there is no need for interfaces. The whole simulation can be one single rotating domain.

When you make it a single domain then these errors will disappear.

[-Maxim-]

Shouldn't be 'number of passages in 360' your number of blades in 360 degrees? Have you tried to put 8 in there?

and I think you're missing an interface for your shroud tip:


For full 360 degrees simulations, I'm using turbo rotation for my cases. I basically have tunnel (inlet) -- blade row -- tunnel (outlet). I have 4 blades but I only import 1 blade into Pre. Then I right-click on the TurboGrid Mesh of the blade and select 'Mesh transformation', where I can choose 'turbo rotation'.
passages per mesh: 1
passages to model: 4
passages in 360: 4
I click I apply and Pre copies that mesh three times so that I have a full 360 degrees mesh.

[aja1345]

Originally Posted by ghorrocks

My post #4 explains what you need to do to get this working.



If you have stationary components and rotating components then you need to put them in stationary or rotating domains and link them with GGIs. But in this case you only have a rotating component so there is no need for interfaces. The whole simulation can be one single rotating domain.

When you make it a single domain then these errors will disappear.

Thanks.

I investigate your statements.

Originally Posted by -Maxim-

Shouldn't be 'number of passages in 360' your number of blades in 360 degrees? Have you tried to put 8 in there?

and I think you're missing an interface for your shroud tip:


For full 360 degrees simulations, I'm using turbo rotation for my cases. I basically have tunnel (inlet) -- blade row -- tunnel (outlet). I have 4 blades but I only import 1 blade into Pre. Then I right-click on the TurboGrid Mesh of the blade and select 'Mesh transformation', where I can choose 'turbo rotation'.
passages per mesh: 1
passages to model: 4
passages in 360: 4
I click I apply and Pre copies that mesh three times so that I have a full 360 degrees mesh.

Yes, I put value of 8 in number of passages in 360, but still there is the following error:



But "passages to model" is 1 in this simulation. I am not sure about "passages to model".

What is your exact meaning of "interface for your shroud tip"?

Thanks,