CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

Turbomode of CFX

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 25, 2012, 06:23
Default Turbomode of CFX
  #1
Member
 
Domenico
Join Date: Sep 2009
Location: Cranfield
Posts: 48
Rep Power: 16
c120613 is on a distinguished road
Dear all,

I'm trying to post-process in CFX and use the turbomode of CFX. I've got a compressor fan having a certain number of blades and I'm interested to see and compare trends of quantities along the span location averaged along the circumferential domain of each blade passage. By default, the initialization in turbomode take into account the full annulus and the initialization can be done only if the option '360 Case without Periodics' is enabled. Then, I used to define the sub-domains (hub, shroud, blade, inlet, and outlet), referred to only one specific blade passage. However there are no differences against the full annulus solution. In fact, if I try to plot the Turbo chart 'Hub to Shroud' the trend of a quantity (which is averaged along the circumferential direction) along the span is always the same. It seems that the limit of the circumferential location over which the average of the quantity is done is always from 0 to 360 degree, even though the Turboregions are referred to a specific blade passage.

Does anyone knows how I can solve this problem instead of creating matlab codes to divide the information between blades?

Thank you in advance for your collaboration
c120613 is offline   Reply With Quote

Old   July 26, 2012, 09:38
Default
  #2
New Member
 
Ismael
Join Date: Nov 2011
Posts: 13
Rep Power: 14
ismael.s is on a distinguished road
Hello.

Is your geometry a periodic of the fan or the full geometry? 360° I mean.

Can you post an Isometric view of your fan?
ismael.s is offline   Reply With Quote

Old   July 26, 2012, 09:53
Default Turbomode
  #3
Member
 
Domenico
Join Date: Sep 2009
Location: Cranfield
Posts: 48
Rep Power: 16
c120613 is on a distinguished road
It is a full annulus. You can see from the picture. The mesh was originally created by means of Turbogrid and automatically for each blade there are the sub-domains defined. Do you have then an idea how to separate the post-processing according to the blade passage?

Thank you in advance for your collaboration
Attached Images
File Type: jpg Screenshot-1.jpg (31.0 KB, 105 views)
c120613 is offline   Reply With Quote

Old   July 26, 2012, 10:02
Default
  #4
New Member
 
Ismael
Join Date: Nov 2011
Posts: 13
Rep Power: 14
ismael.s is on a distinguished road
I usually separate the blade passage when I draw on CAD software.

In the POST, do you try to initialize just the impeller? What error do you get when you try to initialize?

Maybe you can try to look the regions that the software is trying to create and then indicate just the Hub, Shroud and the blades,not doing the automatic initialization and specifying as 1 passage only.

Did you try something like this?
ismael.s is offline   Reply With Quote

Old   July 26, 2012, 10:15
Default
  #5
Member
 
Domenico
Join Date: Sep 2009
Location: Cranfield
Posts: 48
Rep Power: 16
c120613 is on a distinguished road
I tried exactly like that. I took the subdomains referred to one passage only (inlet, hub, shroud, blade and finally the periodics which you must select in the turboregions without having any error). Although you do not have error the solution is the same as the full annulus one. Does it seem right for you?

Thank you for your collaboration
c120613 is offline   Reply With Quote

Old   July 26, 2012, 10:26
Default
  #6
New Member
 
Ismael
Join Date: Nov 2011
Posts: 13
Rep Power: 14
ismael.s is on a distinguished road
The solution won't change, it should be the same, the only difference is the way you are plotting it.

So it seems right.

Did you create your turbo surface at 0.5 spam without problem?
ismael.s is offline   Reply With Quote

Old   July 26, 2012, 10:52
Default
  #7
Member
 
Domenico
Join Date: Sep 2009
Location: Cranfield
Posts: 48
Rep Power: 16
c120613 is on a distinguished road
Yes, I plotted and I was expecting that the turbosurface was referred only to a single passage, but it consider always the full annulus. Is it possible that I cannot split the information according to the blade passage? So far I used to create table where the number of lines was that of the number of blade. Then along the column I calculated a specific quantity referred to each blade passage. In my case I want a trend referred to each passage. This means that I want per each blade a 1D post-processing (where the dimension involved is for example the radial direction), rather than 0D (when for example you do simply an area or mass flow average).
I do not see why it does not work that. I tried even to submit a request to Ansys, but since yesterday they are not replying.

Thank you for your time, really! I hope you have understood my point and you have the solution in your hands.

Cheers
c120613 is offline   Reply With Quote

Old   July 26, 2012, 13:19
Default
  #8
New Member
 
Ismael
Join Date: Nov 2011
Posts: 13
Rep Power: 14
ismael.s is on a distinguished road
'Yes, I plotted and I was expecting that the turbosurface was referred only to a single passage, but it consider always the full annulus. Is it possible that I cannot split the information according to the blade passage?'

You won't be able to split now, you need to do this at the start in the geometry. You can split the geometry,prepare, run, view results. Viewing the results of a periodic you can fill to "complete" the geometry, I think you cannot do the inverse in CFX post, drawing, preparing and running the 360°, then split in the post.

To get information of a single blade, as I understood, would be better to split that fan. Like, I think you have 22 blades, couldn't count well. Get your geometry and split in 22 parts, modeling just one blade and run a periodic simulation, then you will be able to plot 1 blade or the fan.

I have to say, I didn't understand very well what you want to know, but I think you want to plot the information for one blade, right? Streamlines, direction vectors, velocity, velocity in stn frame.

I didn't understand what you mean as 1D and 0D post processing.

I work with pumps and I use do what I told you.

I hope someone can help your better, I guess I did what I could.

ismael.s is offline   Reply With Quote

Old   April 26, 2016, 04:26
Default
  #9
Member
 
ngoc tran bao
Join Date: Jan 2016
Posts: 35
Rep Power: 10
ngoc_tran_bao is on a distinguished road
Quote:
Originally Posted by ismael.s View Post
You won't be able to split now, you need to do this at the start in the geometry. You can split the geometry,prepare, run, view results. Viewing the results of a periodic you can fill to "complete" the geometry, I think you cannot do the inverse in CFX post, drawing, preparing and running the 360°, then split in the post.

Hi, my friend. I got a trouble which is exact what you referred to. I have a full geometry of a pump and I can not initialize it in CFX-post. There is always an error like this: "Please verify that the rotation axis and turbo regions are set correctly" even when I set them carefully in previous steps. I am wondering if Turbo Tab only work with periodic geometries, not full geometries? I also try to initialize a periodic example model and it work well. If I am wrong, can you give me some points? Thank you in advance.
ngoc_tran_bao is offline   Reply With Quote

Old   April 26, 2016, 04:46
Default
  #10
Senior Member
 
Maxim
Join Date: Aug 2015
Location: Germany
Posts: 415
Rep Power: 12
-Maxim- is on a distinguished road
Is your rotation axis the z-axis? I know that TurboGrid needs the z-axis as axis of rotation - maybe Turbo in Post needs that as well.
Turbo Tab can work with full geometries - which is bad since we can evaluate single blades anymore - that's what we also discuss here
-Maxim- is offline   Reply With Quote

Old   April 26, 2016, 05:13
Default
  #11
Member
 
ngoc tran bao
Join Date: Jan 2016
Posts: 35
Rep Power: 10
ngoc_tran_bao is on a distinguished road
Quote:
Originally Posted by -Maxim- View Post
Is your rotation axis the z-axis? I know that TurboGrid needs the z-axis as axis of rotation - maybe Turbo in Post needs that as well.
Turbo Tab can work with full geometries - which is bad since we can evaluate single blades anymore - that's what we also discuss here

Yes, the rotation axis is z, as shown on this picture.
ngoc_tran_bao is offline   Reply With Quote

Old   April 26, 2016, 05:51
Default
  #12
Senior Member
 
Maxim
Join Date: Aug 2015
Location: Germany
Posts: 415
Rep Power: 12
-Maxim- is on a distinguished road
sorry I can't help you here any further since I use a "turbo rotation" in PRE and therefore I don't use a real 360° model.
I would try the bruteforce method I no one else can help you: strip down your simulation to only the important parts to make sure that nothing else interferes. Maybe even set up a simplified case. And/or check out the tutorials. Maybe you forgot a simple thing...
-Maxim- is offline   Reply With Quote

Old   May 7, 2020, 13:51
Default
  #13
New Member
 
Luca
Join Date: Jun 2017
Location: Italy
Posts: 5
Rep Power: 8
LuComet is on a distinguished road
Quote:
Originally Posted by c120613 View Post
Dear all,

I'm trying to post-process in CFX and use the turbomode of CFX. I've got a compressor fan having a certain number of blades and I'm interested to see and compare trends of quantities along the span location averaged along the circumferential domain of each blade passage. By default, the initialization in turbomode take into account the full annulus and the initialization can be done only if the option '360 Case without Periodics' is enabled. Then, I used to define the sub-domains (hub, shroud, blade, inlet, and outlet), referred to only one specific blade passage. However there are no differences against the full annulus solution. In fact, if I try to plot the Turbo chart 'Hub to Shroud' the trend of a quantity (which is averaged along the circumferential direction) along the span is always the same. It seems that the limit of the circumferential location over which the average of the quantity is done is always from 0 to 360 degree, even though the Turboregions are referred to a specific blade passage.

Does anyone knows how I can solve this problem instead of creating matlab codes to divide the information between blades?

Thank you in advance for your collaboration
Dear Domenico, I know that some years have passed, but I'm facing exactly the same problem.

I'm post-processing full annulus results of an axial rotor in CFD-Post, and the inlet conditions are not uniform. Therefore, for each rotor passage, I want to export circumferentially-averaged spanwise profiles of inlet and outlet variables, in order to obtain for example the spanwise distribution of pressure ratio of one passage.

In the Turbo menu, I initialize the domain considering the mesh regions of one passage, and I set a Turbo Chart in order to create the area average spanwise profile of a variable (e.g. Total Pressure in Stn Frame ACA on Hub to Shroud Line). However, for different passages, the exported spanwise profiles are always the same, so I think that CFD-Post is still averaging over the 360° and not over the domain that I specified.

Did you manage to find a workaround? Thank you!
LuComet is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
CFX Treatment of Laminar and Turbulent Flows Jade M CFX 18 September 15, 2022 08:08
High Resolution (CFX) vs 2nd Order Upwind (Fluent) gravis ANSYS 3 March 24, 2011 03:43
CFX pressure in Simulations problem nasdak CFX 1 April 14, 2010 14:22
PhD using CFX Rui CFX 9 May 28, 2007 06:59
FSI using CFX and ANSYS Bi Chang CFX 2 May 10, 2005 05:47


All times are GMT -4. The time now is 22:07.