Adding Multiple Reaction Mechanisms for Multiple Fuels
 

Hello All,

I have a case where I am simulating a Bunsen-type Burner. The fuel is Methane ejecting from the main nozzle; however, it is surrounded by a co-flame of Ethylene-air mixture. Is there an option to import 2 mechanisms for the Methane (GRI-3.0) and Ethylene (UCSD) and define each mechanism for each nozzle?

Hi,
you can merge the mechanisms in the mechanism tab.

Hi Tobias,

Do you mean merging the two mech.dat files before importing them as one to CONVERGE, or can I import the two files separately? Because I tried the 2nd option and it does not work. Whatever I import at the beginning, if I add a second file, it will erase the previous one.

No I mean the chemistry module (second tab on the bottom left). There you can import two mechanisms and merge them together. Then you import the new files into your case setup.

Thank you so much Tobias for your clarification,

I have used the utility successfully and validated the results.

However, may I ask you a favor, please? If possible, can you provide me with or recommend simplified reaction mechanisms for Methane - Ethane - Propane - Ethylene?

I dont have mechanisms for these fuels, only one I have used is GRIMech3 for Methane.


Try these from Cantera: https://www.cerfacs.fr/cantera/mechanisms/meth.php


or CRECK modeling group:
https://creckmodeling.chem.polimi.it/menu-kinetics/menu-kinetics-reduced-mechanisms/

Hello Abdalrazik,

Here are a few options :

1. If you do not possess an established single reaction mechanism for Methane+Ethylene for your operating conditions, as Tobias suggested, you can merge two independent mech.dat mechanisms (one for Methane and one for Ethylene) using our Mechanism Merge tool within the Chemistry Module dock in CONVERGE Studio. You can use this single merged reaction mechanism (mech.dat and therm.dat) for your simulations, but it is strongly recommend you validate this merged mechanism with ignition delay and flame-speed data using our 0D/1D tools. The merged mechanism can also be tuned/re-calibrated to match expected behavior using our Mechanism Tune utility. Please refer to our Manual on how to use the above tools.

2. While we cannot provide multiple species-specific mech.dats, with CONVERGE v3.1 we are able to specify multiple "stream"-specific mech.dats. You can split the computational domain into multiple streams/sub-volumes and direct CONVERGE to use a different mech.dat for each stream using stream-based settings. This might not be feasible for your case, as the two nozzle jets are likely to interact with each other. But this option is available for other problems.

3. With our upcoming v4.0 CONVERGE Studio release (but also available in our current development v3.2 release in our website), you can easily extract a single mechanism for your list of fuel species from a detailed C3 mechanism. Details of the C3 surrogate fuel mechanism can be found here : https://fuelmech.org
The STUDIO tool filters the full C3 mechanism database, which contains over 3,000 distinct species and over 16,000 reactions, to create a reduced mechanism using only the fuel species you select (Methane and Ethylene are available options). You can generate mech.dat, therm.dat, and transport.dat input files and use them in your simulation.
If you do not have access to v3.2 STUDIO, please reach out to us at support@convergecfd.com and we will extract a mechanism from the full C3 mechanism for you. Please use your official email for all correspondence with Convergent Science. Please mention your request and add the cfd-online thread, as reference.

Hope this helps.

Sincerely,