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-   -   SI Engine simulation ECFM: gas.dat, composite species, gas calculator (https://www.cfd-online.com/Forums/converge/231569-si-engine-simulation-ecfm-gas-dat-composite-species-gas-calculator.html)

 JP92 November 10, 2020 09:28

SI Engine simulation ECFM: gas.dat, composite species, gas calculator

Hello CFD-Community,

I try to setup a engine simulation with the combustion model ECFM and RON95E10.
• I want to use single-species diffusion for the gas simulation and was wondering, which predefined gas (Converge offers AR, CH4, CO, CO2, H2, H2O and N2) I should use for a proper simulation.
Furthermore more I would like to know, if it makes sense to define a gas for example, which is a mixture out of C8H18 and air. I assume, I would need to use the implemented "Gas calculator", which demands a bunch of regression coefficients to calculate the conductivity and viscosity for the gas.dat.

Where do I get these coefficients?
Does anyone have further information (websites, books etc.) or hints regarding this topic and how it works?:confused:
• Another approach is to use the option "composite species" to define a composite species of the fuel and use it as the evaporation source of the spray modeling and as the fuel species for the ECFM Model.

What can I aspect from this option?
Does this option primarily influence the performance of my simulation in terms of runtime and efficiency, due to the fact, that I reduce the fuel species to one fuel species.
Or does it even influence the quality of my simulation?

Thanks a lot in advance! :)

 SamWijey November 11, 2020 11:07

Hello,

You can use the gas.dat values for Air for this case. You can take it from any of our engine example cases.

Thanks,

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