Single flamelet extinguished error from chemical reaction problem

Jenny_Wong · March 16, 2012, 04:50

Hi Everyone,
I'm trying to set up a chemical reaction case in FLUENT. It is a single step irreversible reaction of HCl and NaOH (both are liquid). I have created CHEMKIN Mechanism file and Thermodynamic Database file. The reaction data I wrote is:

ELEMENTS
H O NA CL
END
SPECIES
NACL NAOH HCL H2O
END
REACTIONS
NAOH + HCL => NACL + H2O 2.81E-10 0.0 0.0
END

I use non-premixed combustion and steady flamelet model. I am able to load both reaction and thermodynamic files but when I click create flamelet option, FLUENT reports this error:
"Single flamelet extinguished. Try again with lower Scalar Dissipation"

I try reducing the initial scalar dissipation to a very lower number but still, it does not work.

I do not know what is wrong. Can anyone give me some advice/suggestion on how to solve this problem, please? Thank you very much.

Regards,
Jenny

cguy · March 17, 2012, 06:36

The flamelet solver in Fluent checks for heat release to ensure that the flamelet has not extinguished (ie the max temp > boundary temp). Can you give your chemistry some exo-thermistry? (ie lower formation enthalpy of products)

Jenny_Wong · March 17, 2012, 08:01

Dear Cguy,
Thank you very much for your reply. I don't know how to give my chemistry exo-thermistry or lower product formation enthalpy. Could you please give me some ideas?
Best wishes,
Jenny

March 16, 2012, 04:50	Single flamelet extinguished error from chemical reaction problem	#1
Jenny_Wong New Member Jenny Join Date: Jan 2012 Posts: 11 Rep Power: 14	Hi Everyone, I'm trying to set up a chemical reaction case in FLUENT. It is a single step irreversible reaction of HCl and NaOH (both are liquid). I have created CHEMKIN Mechanism file and Thermodynamic Database file. The reaction data I wrote is: ELEMENTS H O NA CL END SPECIES NACL NAOH HCL H2O END REACTIONS NAOH + HCL => NACL + H2O 2.81E-10 0.0 0.0 END I use non-premixed combustion and steady flamelet model. I am able to load both reaction and thermodynamic files but when I click create flamelet option, FLUENT reports this error: "Single flamelet extinguished. Try again with lower Scalar Dissipation" I try reducing the initial scalar dissipation to a very lower number but still, it does not work. I do not know what is wrong. Can anyone give me some advice/suggestion on how to solve this problem, please? Thank you very much. Regards, Jenny

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March 17, 2012, 06:36		#2
cguy New Member Graham Join Date: Apr 2009 Posts: 7 Rep Power: 17	The flamelet solver in Fluent checks for heat release to ensure that the flamelet has not extinguished (ie the max temp > boundary temp). Can you give your chemistry some exo-thermistry? (ie lower formation enthalpy of products)

March 17, 2012, 08:01		#3
Jenny_Wong New Member Jenny Join Date: Jan 2012 Posts: 11 Rep Power: 14	Dear Cguy, Thank you very much for your reply. I don't know how to give my chemistry exo-thermistry or lower product formation enthalpy. Could you please give me some ideas? Best wishes, Jenny