[Christina123]

Hi,
If I want to see the emissions, should I check the file emission.out or view the file emission_region2.out?（PS: region2 is the exhaust area.）Can I check the specific emission directly? Or do I need to calculate it myself?
Looking forward to your reply. Thank you very much.

[nitesh.attal]

Originally Posted by Christina123

Hi, If I want to see the emissions, should I check the file emission.out or view the file emission_region2.out?（PS: region2 is the exhaust area.）Can I check the specific emission directly? Or do I need to calculate it myself?
Looking forward to your reply. Thank you very much.

What are the emission related quantities are you interested in?


emissions.out or emissions_region*.out report mean quantities over the entire domain or sub-domain (corresponding to a region). Some of the precomputed mean quantities in these files are NOx, HC, CO, CO2, etc (kg and mole fraction).



If you are interested in species mass(or mole or mass fraction), e.g. NO, NO2, CO, CO2 etc. you can monitor their mean quantities in species_mass_region*.out. If you rather want to look at the 3D field (post*.out), you can enable writing them in post files (post.in).



Thanks,

[Christina123]

Sorry, I still don't understand. Can you tell me in detail how can I get the quality of the NOX emitted by the engine?

[nitesh.attal]

Please look at NOX in the cylinder region at EVO.



If you compare with experiments, ensure that the quantities being compared are consistent. If your reaction mechanism has NO, NO2 etc., these can be accessed through species_mass_region*.out, species_mass_fraction_region*.out or species_mole_fraction_region*.out


If your reaction mechanism does not contain NO, NO2, ect, then you can use passive NOX which can be accessed from passive_region*.out file. In this model, a factor of 1.533 (ratio of molecular weights of NO to NO2) is used to convert the predicted NO to NOx. You must verify that the factor reflects the experimental measurements for conversion of NO to NO2 (by mass). If the experimental measurements report only NO or if both NO and NO2 were measured, then this value may change and you can change the nox_scaling_factor in emissions.in to the appropriate value.

Originally Posted by Christina123

Sorry, I still don't understand. Can you tell me in detail how can I get the quality of the NOX emitted by the engine?

[Christina123]

Thank you for your reply. I have another question to ask you for advice. I hope that the results（such as the specific emissions of soot or NOX,HC emission concentration,etc） obtained through 3D simulation match the experimental results.But now I get a big difference between the simulation results and the experimental data. What parameters can be adjusted to make the simulation results consistent with the experimental data more effectively?

Thank you for your reply. Looking forward to your reply.

[SamWijey]

Hello,

In order for emissions predictions to match measured data, we need to make sure several quantities are correctly predicted. Some of these are cylinder pressure, heat release, trapped mass, and wall heat loss. In order to guide you through matching all these quantities, we will have to take this discussion beyond this forum. Can you email us at support@convergecfd.com using your official email so we can help you figure out why the emission predictions do not match measured data?