CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLUENT

Reversed Flow Outlet- Transient- Turbine

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

Like Tree1Likes
  • 1 Post By blackmask

Reply
 
LinkBack Thread Tools Display Modes
Old   March 11, 2013, 02:35
Default Reversed Flow Outlet- Transient- Turbine
  #1
New Member
 
Gowrav Shenoy
Join Date: Feb 2013
Posts: 20
Rep Power: 4
Gowrav is on a distinguished road
Hi,
I am doing transient analysis of Microturbine to evaluate fluid flow. 1.5 million elements. Using Sliding Mesh technique. Pr.Ratio- 4 atm. Rotating Speed 75krpm. I am able to get Convergence after 500 timestep of 2.2e^-6 s each. But am getting reversed flow at pressure outlet. As one of the suggestion mentioned in forum i have extended outlet volume length. Now my L/d ratio is 2. But problem nt resolved. Looking for help.

Thanks in Advance
Gowrav
Gowrav is offline   Reply With Quote

Old   March 11, 2013, 04:17
Default
  #2
Senior Member
 
Join Date: Aug 2011
Posts: 315
Rep Power: 11
blackmask will become famous soon enough
Turn on Radial Equilibrium Pressure Distribution to see if it helps. It is not uncommon that reversed flow appear in the outlet after a strong vortex core formed. You can check the velocity contour of the outlet to see whether the reversed flow can be neglected. Sometimes they are of relatively small magnitude. Note that the only aim of extension of the computational domain is to facilitate the pressure outlet b.c. which resembles to sponge or buffer region in acoustics calculations. You can put a large-tank-like geometry after the outlet of your real geometry and specify pressure p.c. at the outlet of tank.
Gowrav likes this.

Last edited by blackmask; March 11, 2013 at 05:06.
blackmask is offline   Reply With Quote

Old   March 11, 2013, 10:32
Default hey
  #3
New Member
 
ali m
Join Date: Oct 2012
Posts: 8
Rep Power: 4
ali_mehrabi69 is on a distinguished road
hey Gawrev


Im working on a micro turbine with 100krpm too.I am trying to model it, as steady state
problem in different angles. but im not sure about it,
how did you design the mechanical parts?like turbine shape,blades and...
from which software did you use?

thank u
ali_mehrabi69 is offline   Reply With Quote

Old   March 12, 2013, 02:41
Default Reply to Ali
  #4
New Member
 
Gowrav Shenoy
Join Date: Feb 2013
Posts: 20
Rep Power: 4
Gowrav is on a distinguished road
Quote:
Originally Posted by ali_mehrabi69 View Post
hey Gawrev


Im working on a micro turbine with 100krpm too.I am trying to model it, as steady state
problem in different angles. but im not sure about it,
how did you design the mechanical parts?like turbine shape,blades and...
from which software did you use?

thank u
Hi, Ali
I am doing analysis part of MGT.. Design Even i am not sure, how it modeled.. It is a 8 blades -Twisted blade- axial turbine.. I have got ref. mat. for design of radial turbine for 40k,, its there in Google.. , i am also trying to find out its velocity triangles... Software as per my knowledge if you have dim. BladeGen will do.. If you can share some more info forum may give you right tip.
Bye
Gowrav is offline   Reply With Quote

Old   March 12, 2013, 02:43
Default
  #5
New Member
 
Gowrav Shenoy
Join Date: Feb 2013
Posts: 20
Rep Power: 4
Gowrav is on a distinguished road
Quote:
Originally Posted by blackmask View Post
Turn on Radial Equilibrium Pressure Distribution to see if it helps. It is not uncommon that reversed flow appear in the outlet after a strong vortex core formed. You can check the velocity contour of the outlet to see whether the reversed flow can be neglected. Sometimes they are of relatively small magnitude. Note that the only aim of extension of the computational domain is to facilitate the pressure outlet b.c. which resembles to sponge or buffer region in acoustics calculations. You can put a large-tank-like geometry after the outlet of your real geometry and specify pressure p.c. at the outlet of tank.
Hi Blackmask,
I am working on your suggestion..
Am also trying to increase the number of timesteps..
Thanks
Gowrav
Gowrav is offline   Reply With Quote

Old   March 15, 2013, 13:33
Default hey
  #6
New Member
 
ali m
Join Date: Oct 2012
Posts: 8
Rep Power: 4
ali_mehrabi69 is on a distinguished road
Quote:
Originally Posted by Gowrav View Post
Hi, Ali
I am doing analysis part of MGT.. Design Even i am not sure, how it modeled.. It is a 8 blades -Twisted blade- axial turbine.. I have got ref. mat. for design of radial turbine for 40k,, its there in Google.. , i am also trying to find out its velocity triangles... Software as per my knowledge if you have dim. BladeGen will do.. If you can share some more info forum may give you right tip.
Bye
im working on a radial turbine,a simple radial turbine,like a pelton turbine, with nozzles, and use air,for fluid.
i have problem with CFD analysis,
im working with fluent,

did u do CDF analysis?

tanx
ali_mehrabi69 is offline   Reply With Quote

Old   March 15, 2013, 14:52
Default Reply to Ali
  #7
New Member
 
Gowrav Shenoy
Join Date: Feb 2013
Posts: 20
Rep Power: 4
Gowrav is on a distinguished road
Hi ali,,
Yours your s quite interesting. If you can tell whats the difficulty, then i can give my opinion.. I am using Fluent-14, for analysis. Its Transient,, and using sliding Mesh..
Gowrav is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Reversed flow in XXX faces on pressure outlet parradux FLUENT 6 May 2, 2015 04:26
reversed flow in xxxx faces on pressure outlet franzdrs FLUENT 6 March 19, 2014 04:16
Reversed Flow in Outlet Steve FLUENT 18 March 30, 2013 08:50
ATTENTION! Reliability problems in CFX 5.7 Joseph CFX 14 April 20, 2010 15:45
unbounded reversed flow on outlets kwardle OpenFOAM 7 May 18, 2009 15:23


All times are GMT -4. The time now is 22:02.