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Karla Medina February 23, 1999 15:41

Flamelet in CFX-TASCflow

I am a user of CFX-TASCflow. I intend to use the combustion models offered in this program. There are two models offered: the Multi-step Eddy-Dissipation and the Flamelet. Which in your opinion would you recommend to use, ie, what are the advantages and disadvantages for each model?



Heinz Wilkening February 24, 1999 09:04

Re: Flamelet in CFX-TASCflow

for what subject you want to model combustion? Turbulent or laminar? What are you interessted in?

I do not know the actual model in CFX, but in general the model to use depents very much on your application.

Ciao Heinz

Karla Medina February 24, 1999 13:40

Re: Flamelet in CFX-TASCflow

I am trying to model a turbulent combustion of jets-in-crossflow for various mass flow ratios. I will be looking at CO and H2 species and compare them to literature.

Thanks, Karla.

Heinz Wilkening February 25, 1999 14:29

Re: Flamelet in CFX-TASCflow

if you have something (literature) to compare to, I would recomment to try both models to see which one is best for your applications.

I am sorry not to be able to give a better answer, but in turbulent combustion modeling - I guess your application will be turbulent - there is no ultimate best method at the moment.

If somebody things I am wrong please tell me, because I am working also in that field, and I am searching for the best model for my application too. :)

Ciao Heinz

Jorge Ferreira February 25, 1999 16:00

Re: Flamelet in CFX-TASCflow
Hi Karla,

TASCflow offers several different combustion models. It depends on the application to decide which model should be selected. For the overall heat release the EDM and the flamelet model give similar results, and it does not matter much which model you select; although the EDM in general slightly overpredicts the temperature. The EDM has the advantage that it can be used for non-premixed, premixed, and partially premixed systems. It is very robust and allows the implementation of kinetic data, which strictly speaking is only valid for homogenoeus systems. The coupled solver of TASCflow allows you to solve multistep chemistry very efficiently. The disadvantage is that in many cases one has to modify the empirical constants in the model and the prediction of minor species is not very reliable. The flamelet model has the advantage that it provides detailed information on minor species as it recovers the detailed local flame structure of the flame. TASCflow offers also a flame front model which in combination with the flamelet model can be used to model lifted partially premixed flames that can be found in gas turbine combustors. The disadvantage of the flamelet model is that flamelet libraries must be provided that are in line with the problem you are looking at. To summarize: If you are only interested in the heat release then I would start with the EDM. If you need information on minor species then the flamelet model is the better choice.

We hope that this reply will solve your question. Please do not hesitate to contact your AEA customer support in case of more questions.



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