[ankitraut27]

Hi everyone,

I am using ECFM3Z combustion model for GDI engine simulation with C8H18 as fuel. I need therm.dat file for that.
Converge message log showing that "properties of BFUEL, UNIMIXFUEL, UNIMIXO2 are unknown". What does this mean?
Please help!

[nitesh.attal]

Hello Ankit,

The bfuel and unmixfuel will have the same thermodynamic properties as your fuel (C8H18) while unmixo2 will have the same properties as species O2.

Please copy the content (polynomial coefficients) corresponding to C8H18 in therm.dat twice at the end of thermo.dat (line before END) and rename them as (a) bfuel and (b) unmixfuel. Similarly, copy the contents corresponding to O2 and rename it as unmixO2. As a reference, please use the therm.dat in our SI8 ECFM/3Z example cases.

Thanks,

[ankitraut27]

Thanks Nitesh for reply

I have one more query.
What is difference between ECFM and ECFM3Z model? Can I use ECFM3Z model for PFI and GDI engine simulation?

[nitesh.attal]

The Extended Coherent Flamelet Model (ECFM) is a combustion model for premixed combustion while ECFM3Z (ECFM 3 zone) is for non-premixed combustion. You can find more details on the models and its applicability in CONVERGE's user manual and references therein.

Thanks,

[Night Nine]

I have made copy of the properties of fuel and o2, and renamed them. But it did not work, the message log showed that more species become unknown. How to fix this problem?

[nitesh.attal]

Please share the exact error message and the modified therm.dat.
After the modifications in therm.dat file, does Studio show any error?

Originally Posted by Night Nine

I have made copy of the properties of fuel and o2, and renamed them. But it did not work, the message log showed that more species become unknown. How to fix this problem?

[Night Nine]

Originally Posted by nitesh.attal

Please share the exact error message and the modified therm.dat.
After the modifications in therm.dat file, does Studio show any error?

First I choose the ECFM-3Z model, and the errors are showed below:
 [Gas] -> Properties of Gas 'BFUEL' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'UNMIXFUEL' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'UNMIXO2' are unknown. No such entry found within 'therm.dat' configuration.

Then I followed the instructions and made two copies of CH4 and one copy of o2 and renamed them in therm.dat, then the errors are showed below:
Gas simulation
 [thermDatData] -> Gas thermodynamic data is not defined. You have to import it.
Species
 [Gas] -> Properties of Gas 'CH4' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'BFUEL' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'O2' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'N2' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'CO2' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'CO' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'H2' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'H2O' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'O' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'N' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'H' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'OH' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'UNMIXFUEL' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'UNMIXO2' are unknown. No such entry found within 'therm.dat' configuration.

I don't know how to attach the file, the attachment icon has no reaction.So the therm.dat is not here.
If you are convenient please leave a e-mail address, I will send the therm.dat

[MFGT]

This may be related to this: https://en.wikipedia.org/wiki/Newline
make sure you have species seperated by CR LF

[nitesh.attal]

Looks like the modified therm.dat is not in the correct format.


Please send the original and modified therm.dat (or the complete case setup) to support@convergecfd.com using your official email address (used for verification) for us to fix the file for you.

Originally Posted by Night Nine

First I choose the ECFM-3Z model, and the errors are showed below:
 [Gas] -> Properties of Gas 'BFUEL' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'UNMIXFUEL' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'UNMIXO2' are unknown. No such entry found within 'therm.dat' configuration.

Then I followed the instructions and made two copies of CH4 and one copy of o2 and renamed them in therm.dat, then the errors are showed below:
Gas simulation
 [thermDatData] -> Gas thermodynamic data is not defined. You have to import it.
Species
 [Gas] -> Properties of Gas 'CH4' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'BFUEL' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'O2' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'N2' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'CO2' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'CO' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'H2' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'H2O' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'O' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'N' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'H' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'OH' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'UNMIXFUEL' are unknown. No such entry found within 'therm.dat' configuration.
 [Gas] -> Properties of Gas 'UNMIXO2' are unknown. No such entry found within 'therm.dat' configuration.

I don't know how to attach the file, the attachment icon has no reaction.So the therm.dat is not here.
If you are convenient please leave a e-mail address, I will send the therm.dat