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-   -   Effect of heat loss ratio dimension on FGM table (https://www.cfd-online.com/Forums/main/227054-effect-heat-loss-ratio-dimension-fgm-table.html)

twb2k8 May 15, 2020 14:14

Effect of heat loss ratio dimension on FGM table
 
I am performing a RANS simulation of a turbulent premixed flame, with an isothermal wall set at 600 K. To simulate the flame, am using the FGM method with progress variable, mixture fraction and heat loss ratio as controlling variables. I am comparing my results with a simulation that does not include heat loss ratio in its flamelet tabulation and underpredicts peak flame temperature.

I want to better understand why the inclusion of heat loss ratio in the table results in a better prediction of peak temperature. My understanding so far is:
  • Temperature is computed during FGM tabulation using the enthalpy equation: "H2 - H1 = Cp(T2 - T1)"
  • In a table with no heat loss, heat capacity is associated with a synchronised change between temperature and mixture fraction, as progress variable changes
  • Being able to access the table with heat loss ratio as a controlling variable allows for different heat capacities and subsequently different temperatures to be retrieved for any given progress variable
  • Because of this, temperatures away from the wall can still be high whilst near wall temperatures are cool

Is what I'm saying correct? I think there's some gaps in my understanding, particularly with the effect of different heat capacities on how temperature is obtained by the solver accessing the table, near and away from the wall.

Thanks for any help you can give!


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