Injection problem in FGM simulation

Ale_DM · April 20, 2021, 11:28

Hi everyone,

I am having some problems trying to inject H2O and CH4 together, both in gaseous form and from the same inlet. I am using Converge 2.4 and this is a gas-turbine combustor application.
The problem is the following:
- keeping the combustion model (FGM) activated, the only fluid being injected throughout the simulation is CH4. Even if I impose 100% water to be injected, CH4 is injected instead.
- If I disable the combustion model, water is properly injected.

These considerations are based on the analysis of the "regions_flow.out" file and on further post precessing of the 3D output files.
Have someone encountered a similar issue and would like to help me on this?

ksrivast · April 20, 2021, 12:19

Hello Alessandro,

It is likely that the user generated the FGM table using CH4 as fuel. When you switch to H2O or a blend of CH4 and H2O, you are not re-generating the FGM table. That is why no matter what change you make, you are getting CH4 from inlet.

For further assistance, could you forward your case setup to support@convergecfd.com? Please use your official email for all correspondence with Convergent Science. Please mention the issues you're facing, attach your case setup and add the cfd-online thread, as reference.

Sincerely,

Ale_DM · April 20, 2021, 12:33

Hi Kislaya,

Thank you very much for the reply. I think I got what the problem is now. However, how should I solve this? I mean, the FGM panel gives me the possibility to only select a single species for my fuel, should I create a composite species using the proper panel in converge studio?

Best regards, Alessandro

ksrivast · April 20, 2021, 12:58

Hello Alessandro,

Within v2.4 CONVERGE Studio, under Combustion modeling > Models (FGM) > FGM Setup > Species in fuel, you should be able to specify a list of species and their corresponding mass fractions. Click the Add (green plus mark) button to add more species. List all species from the Inlet. You can also do this directly inside fgm.in, under <fgm_num_species_bc1>.

If you don't see this option available for you in Studio, please ensure you're using our latest version of v2.4 Studio before getting in touch with support@convergecfd.com.

Hope this helps.

Sincerely,

Ale_DM · April 21, 2021, 09:07

Hi Kislaya,

The problem has been solved as you suggested.
Thank you very much for your kind support, it has been really appreciated.

Best regards,
Alessandro

April 20, 2021, 11:28	Injection problem in FGM simulation	#1
Ale_DM New Member Alessandro Join Date: Feb 2021 Posts: 8 Rep Power: 5	Hi everyone, I am having some problems trying to inject H2O and CH4 together, both in gaseous form and from the same inlet. I am using Converge 2.4 and this is a gas-turbine combustor application. The problem is the following: - keeping the combustion model (FGM) activated, the only fluid being injected throughout the simulation is CH4. Even if I impose 100% water to be injected, CH4 is injected instead. - If I disable the combustion model, water is properly injected. These considerations are based on the analysis of the "regions_flow.out" file and on further post precessing of the 3D output files. Have someone encountered a similar issue and would like to help me on this?

April 20, 2021, 12:19		#2
ksrivast Senior Member Kislaya Srivastava Join Date: Sep 2017 Location: Convergent Science, Northville MI Posts: 165 Rep Power: 8	Hello Alessandro, It is likely that the user generated the FGM table using CH4 as fuel. When you switch to H2O or a blend of CH4 and H2O, you are not re-generating the FGM table. That is why no matter what change you make, you are getting CH4 from inlet. For further assistance, could you forward your case setup to support@convergecfd.com? Please use your official email for all correspondence with Convergent Science. Please mention the issues you're facing, attach your case setup and add the cfd-online thread, as reference. Sincerely, __________________ Kislaya Srivastava Principal Research Engineer \| Applications CONVERGECFD

April 20, 2021, 12:58		#4
ksrivast Senior Member Kislaya Srivastava Join Date: Sep 2017 Location: Convergent Science, Northville MI Posts: 165 Rep Power: 8	Hello Alessandro, Within v2.4 CONVERGE Studio, under Combustion modeling > Models (FGM) > FGM Setup > Species in fuel, you should be able to specify a list of species and their corresponding mass fractions. Click the Add (green plus mark) button to add more species. List all species from the Inlet. You can also do this directly inside fgm.in, under <fgm_num_species_bc1>. If you don't see this option available for you in Studio, please ensure you're using our latest version of v2.4 Studio before getting in touch with support@convergecfd.com. Hope this helps. Sincerely, __________________ Kislaya Srivastava Principal Research Engineer \| Applications CONVERGECFD

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April 20, 2021, 12:33		#3
Ale_DM New Member Alessandro Join Date: Feb 2021 Posts: 8 Rep Power: 5	Hi Kislaya, Thank you very much for the reply. I think I got what the problem is now. However, how should I solve this? I mean, the FGM panel gives me the possibility to only select a single species for my fuel, should I create a composite species using the proper panel in converge studio? Best regards, Alessandro

April 21, 2021, 09:07		#5
Ale_DM New Member Alessandro Join Date: Feb 2021 Posts: 8 Rep Power: 5	Hi Kislaya, The problem has been solved as you suggested. Thank you very much for your kind support, it has been really appreciated. Best regards, Alessandro