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-   -   Non-premixed comb. temp prediction; PDF problem (http://www.cfd-online.com/Forums/fluent/38110-non-premixed-comb-temp-prediction-pdf-problem.html)

K. Jagus October 5, 2005 04:30

Non-premixed comb. temp prediction; PDF problem
 
Hello,

I am doing a steady state simulation of combustion in combustion chamber. Fuel is liquid diesel, injected by pressure swirl. The problem is that I do get too high temperature values on the walls of the air blast. 3200K is far too high. The maximum value calculated by the PREPDF was determined to be 2274K. Any suggestions? Is it due to the wrong species chosen in PREPDF? Also, I am unable to read either the pdf table or the input file into the prepdf once i create them. It says couldn't determine the file format and unable tor ead file. Thank You in advance for any suggestions.

RoM October 5, 2005 05:31

Re: Non-premixed comb. temp prediction; PDF proble
 
For high temperature flames (>1500K) dissociated species become important so you will have to include some of them in your pdf. I would add at least OH, O(atomic) and H(atomic) to account for the dissociation of water. Other intermediate species you might consider are CH2O,CO,HNO2 and H2O2.

Good Luck

RoM

K. Jagus October 5, 2005 05:46

Re: Non-premixed comb. temp prediction; PDF proble
 
I will be trying this shortly. Thank You very much. As for O and H however i think I did include them. Problem is I cannot look up the lookup table in PREPDF:)

Mary October 5, 2005 07:41

Re: Non-premixed comb. temp prediction; PDF proble
 
I had such problem !

Try this in PrePDf

Display-Options-Rendering

and then check Fluent stroked font

Mary

K. Jagus October 5, 2005 08:32

Re: Non-premixed comb. temp prediction; PDF proble
 
I tried it, unfortunately it did not help.


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