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

Flamelet model ,question :

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 30, 2009, 18:03
Question Flamelet model ,question :
  #1
Member
 
AdidaKK's Avatar
 
Mauricio Caamaño Flores
Join Date: May 2009
Location: Punta Arenas, Chile
Posts: 62
Rep Power: 16
AdidaKK is on a distinguished road
Send a message via MSN to AdidaKK
Its possible to work with FLAMELET MODEL in a premixed air/gas ? im simulating a combustion chamber(tubular) of a turbine.

which combustion model do you recommend me for simulate a combustion chamber (tubular) from a turbine Hitachi 24kW.?

thanks very much
AdidaKK is offline   Reply With Quote

Old   July 30, 2009, 21:12
Default
  #2
Member
 
geothokar's Avatar
 
George Thomas
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 59
Rep Power: 17
geothokar is on a distinguished road
Hi,

Flamelet model can be used for modeling premixed and partially premixed combustion as far as I know. However, the model is included as a submodel in CFX (as in V11.0) which you can use with the BVM/TFC model and Laminar flamelet with PDF model. This is explained in the help files in CFX.

You may need to use CFX-RIF to generate your own fluid model which require you to have a separate license. Otherwise you may have to rely on predefined models that comes with CFX.

Refer to the combustor modeling in CFX tutorial, in which they used flamelet model for premixed combustion.
__________________
Cheers,

George

"The fact that I can plant a seed and it becomes a flower, share a bit of knowledge and it becomes another's, smile at someone and receive a smile in return, are to me continual spiritual exercises"Leo.F. Buscaglia
geothokar is offline   Reply With Quote

Old   July 30, 2009, 23:30
Cool
  #3
Member
 
AdidaKK's Avatar
 
Mauricio Caamaño Flores
Join Date: May 2009
Location: Punta Arenas, Chile
Posts: 62
Rep Power: 16
AdidaKK is on a distinguished road
Send a message via MSN to AdidaKK
the version that im using its cfx 10, and i was done the "combustion and radiation" tutorial ,in that tutorial uses the flamelet model and discrete transfer model(for radiation) ,but its a difussion flame(oxider and fuel stream enter separatly).

but i really dont know if exist some tutorial for the implementation of flamelet with premixed flames or partially premixed flames? and i dont know if CFX 10 work with this?

best regards
AdidaKK is offline   Reply With Quote

Old   July 31, 2009, 02:46
Default
  #4
Member
 
geothokar's Avatar
 
George Thomas
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 59
Rep Power: 17
geothokar is on a distinguished road
I do not know how it goes with CFX V10 as I have only experience with V11. However, the V11 is now obsolete with the introduction of V12, though will take some time to change over to V12.

The BVM model can be used for premixed and partially premixed combustion modeling. The combustor simulation using BVM, from what I understand, is shown for partially premixed combustion problem. The reaction progress variable can be hopefully used to control the mixture concentration in any domain during the turbulent simulation.

"mixing of the fuel and oxidant is represented by the mixture fraction, which can be seen as a normalized equivalence ratio. The location of the premixed flame front is determined by a reaction progress variable, where the turbulent burning velocity is used as an input parameter" (ref http://www.esss.com.br/pdf/CFXRCS.pdf)

I'm also in the learning procedure of premixed combustion. These are just my views. However, you can find something useful from the CFX help for BVM modelling.
__________________
Cheers,

George

"The fact that I can plant a seed and it becomes a flower, share a bit of knowledge and it becomes another's, smile at someone and receive a smile in return, are to me continual spiritual exercises"Leo.F. Buscaglia

Last edited by geothokar; July 31, 2009 at 03:25.
geothokar is offline   Reply With Quote

Old   July 31, 2009, 06:41
Smile
  #5
Member
 
AdidaKK's Avatar
 
Mauricio Caamaño Flores
Join Date: May 2009
Location: Punta Arenas, Chile
Posts: 62
Rep Power: 16
AdidaKK is on a distinguished road
Send a message via MSN to AdidaKK
thanks you very very much for your help,im in the learning of premixed moldel too,this is a long way to learn.

thanks again,im gona see the combustion model that you tell me.

best regards.
Mauricio
AdidaKK is offline   Reply With Quote

Old   August 21, 2009, 15:53
Default premixed combustion
  #6
New Member
 
shah samip
Join Date: Aug 2009
Posts: 6
Rep Power: 16
shahsamipp is on a distinguished road
hi...
i m also doing my phd on flammability limits ..... for that also i m working on premixed combustion .... i m having cfx 11 & 12 ...but i m bit confused how to apply Burning Velocity Model (BVM) and Laminar Flamelet with PDF models ...
kindly suggest me some method to apply.......

best regards
shahsamipp is offline   Reply With Quote

Old   August 21, 2009, 20:55
Default
  #7
Member
 
geothokar's Avatar
 
George Thomas
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 59
Rep Power: 17
geothokar is on a distinguished road
Hi,

Its better if you can tell where you are stuck, what is the problem now you are having with the model.

Also, if you can, brief your kind of application. For some cases EDM can be a better choice than BVM/LFC

Also, even if you have both CFX 11 & 12, you may not be encouraged with the performance of BVM model as the CFX comes with two default FLL models only, and so if you need to use a new mixture config, you should have CFX-RIF that comes as a separate license.
__________________
Cheers,

George

"The fact that I can plant a seed and it becomes a flower, share a bit of knowledge and it becomes another's, smile at someone and receive a smile in return, are to me continual spiritual exercises"Leo.F. Buscaglia
geothokar is offline   Reply With Quote

Old   August 25, 2009, 14:02
Default
  #8
New Member
 
shah samip
Join Date: Aug 2009
Posts: 6
Rep Power: 16
shahsamipp is on a distinguished road
thanks for replying....
actually i m doing work on flammability limits...
in this the combustion model is spark ignited...
and i m not having any idea how to define spark in the cfx...
can u give me some guidance for that...
shahsamipp is offline   Reply With Quote

Old   August 25, 2009, 19:53
Default
  #9
Member
 
geothokar's Avatar
 
George Thomas
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 59
Rep Power: 17
geothokar is on a distinguished road
if u r using BVM,

for spark ignition to work, u shuld setup the following factors: spark kernel location, spark energy, energy coefficient, time duration for spark.

all there settings wil get activatd 1nce u choose BVM as comb. model.

& to get the bvm model activatd u shuld select FLL mixtre 1st in the material list and reaction list.

I wuld suggest to go with methane-air mixture.

also is imp. to initialize all parametrs in simulation with sensible values. otrwise everythng wil go crap!!!

if u hav plnty of tym to finish the work u r doing, u'll learn al the abov said things with experience.

if u r stil in starting stage, don't rush 2 get the comb. model. read more articles. get mor idea abt. hw comb. model works. it wil help u. am telng bcoz i hav 1st hand experience with dis kind of modeling.

gud luck
__________________
Cheers,

George

"The fact that I can plant a seed and it becomes a flower, share a bit of knowledge and it becomes another's, smile at someone and receive a smile in return, are to me continual spiritual exercises"Leo.F. Buscaglia
geothokar is offline   Reply With Quote

Old   August 26, 2009, 14:10
Default
  #10
New Member
 
shah samip
Join Date: Aug 2009
Posts: 6
Rep Power: 16
shahsamipp is on a distinguished road
thank you very much for your kind help .....

regards
samip
shahsamipp is offline   Reply With Quote

Old   September 7, 2009, 14:02
Default hi every one
  #11
New Member
 
shah samip
Join Date: Aug 2009
Posts: 6
Rep Power: 16
shahsamipp is on a distinguished road
hi....
as u suggest i did lot s of r & d on BVM/TFC model......
can v find a flame velocity.????/
as per astm std if the flame is reached on the top of 1.8m hight in 50cm tube thn the flame is flammable else not.............
i tried to solve this prob using cfx 11
but getting a error of domain overflow......
how to overcome 4m this........
as in this prob model is spark ignited 4m bottom and top of a cylinder should be closed.......
how to define this type of b c in cfx ........
can any one give me the suggestion
thanks regards
samip shah
shahsamipp is offline   Reply With Quote

Old   September 23, 2009, 06:37
Default
  #12
Member
 
AdidaKK's Avatar
 
Mauricio Caamaño Flores
Join Date: May 2009
Location: Punta Arenas, Chile
Posts: 62
Rep Power: 16
AdidaKK is on a distinguished road
Send a message via MSN to AdidaKK
im studing diffusion laminar flames before work directly with the flamelet model of ansys ,and i have a question:

i have understand that the difussion flames can be split in two problems:
1.-)mixing problem
2.-) a flame structure problem

am i right?..but..the flamelet model of ansys works with fast chemistry(equilibrium wk=0) but with irreversible/reversible/frozen chemistry?
AdidaKK is offline   Reply With Quote

Old   September 24, 2009, 08:29
Default
  #13
Senior Member
 
Join Date: Mar 2009
Location: Europe
Posts: 169
Rep Power: 17
joey2007 is on a distinguished road
The flamelet generator is based on finite rate chemistry. It calculates laminar stretched flames. The "laminar" flamelet model for turbulent flames assumes that the laminar stretch can be correlated to the turbulent. As this is more a theory question, check the books of Peters or Warnatz
joey2007 is offline   Reply With Quote

Old   September 24, 2009, 09:05
Default
  #14
Member
 
AdidaKK's Avatar
 
Mauricio Caamaño Flores
Join Date: May 2009
Location: Punta Arenas, Chile
Posts: 62
Rep Power: 16
AdidaKK is on a distinguished road
Send a message via MSN to AdidaKK
thanks very much! ...my last question....flamelet model its a model who works with irreversible o reversible chemistry?

and what information its in the libraries of flamelets?

thanks very vey much
best regards
AdidaKK is offline   Reply With Quote

Old   September 25, 2009, 17:24
Default
  #15
Senior Member
 
Join Date: Mar 2009
Location: Europe
Posts: 169
Rep Power: 17
joey2007 is on a distinguished road
The flamelet generator is based on complete reaction mechanism with forward and backward reaction. So it is reversible, in the flamelet generator.

The 3D-CFD-solver does not calculate chemical reaction rate when the laminar flamelet model is used. The composition depends on mixture and turbulence, not on chemical kinetics. For practical case I suppose once the fluid has reached chemical equilibrium it will move along the equilibrium line.

Please read the combustion theory books for more details. (It is not CFX specific)
joey2007 is offline   Reply With Quote

Old   September 26, 2009, 04:19
Default
  #16
Member
 
AdidaKK's Avatar
 
Mauricio Caamaño Flores
Join Date: May 2009
Location: Punta Arenas, Chile
Posts: 62
Rep Power: 16
AdidaKK is on a distinguished road
Send a message via MSN to AdidaKK
thanks very much for your help ,im studing with the book
theorical and numerical combustion from thierry poinsot-denis veynante

best regards
AdidaKK is offline   Reply With Quote

Old   November 29, 2021, 07:16
Smile Real gas effect in Ansys
  #17
Member
 
Niyas
Join Date: Apr 2013
Posts: 44
Rep Power: 12
niyas is on a distinguished road
Hi everyone,

I am exploring the possibilities of creating a real-gas flamelet library.

Is it possible to create in ANSYS Fluent or CFX?


Thanks,
Niyas
__________________
Regards,
Niyas
niyas 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
model han Main CFD Forum 0 September 27, 2005 09:35
references about the fan/radiator model Mihai ARGHIR Main CFD Forum 1 January 8, 2001 16:49
references about the fan/radiator model Mihai ARGHIR Main CFD Forum 0 December 21, 2000 04:06
references about the fan/radiator model Mihai ARGHIR Main CFD Forum 1 December 17, 2000 08:01
Advanced Turbulence Modeling in Fluent, Realizable k-epsilon Model Jonas Larsson FLUENT 5 March 13, 2000 04:27


All times are GMT -4. The time now is 10:21.