We’re putting the final touches on our new badges platform. Badge issuance remains temporarily paused, but all completions are being recorded and will be fulfilled once the platform is live. Thank you for your patience.
Fluids

Fluids

Topics related to Fluent, CFX, Turbogrid and more.

Transient FGM (Ignition and Heat Release Rate)

    • Mathieu G
      Subscriber

      Hi,

      I'm running a 3D transient simulation using the Partially Premixed Combustion Non-adibatic FGM model.

      I want to capture the auto-ignition of a hot gas mixture jet.
      I'm initializing my domain with a mixture fraction and progress variable at 0.
      A mass-flow inlet is used to create the jet, the temperature is fixed (800°C) and the mixture fraction is set to 1. I don't observe any ignition unless I'm patching the progress variable or adding a spark

      Is there a way to capture auto-ignition with the FGM model?

      I also have issues with the heat release rate value computed using a Volume-Integral on my domain (From PDF>Heat Release Rate). The value is often negative even when a flame is present.
      According to the User's Guide (p4200), the HRR is the source term defined in eq 5.11 of the Theory Guide. However, the Theory Guide states that when using the non-adiabatic non-premixed combustion model the reaction sources of energy are not included in Eq 5.11. So what hat is Fluent computing as the heat release rate?

      Thank you,

    • Ren
      Ansys Employee

      Hello, Mathieu,

      The FGM is not suitable for predicting auto-ignition. For this purpose, you need to have a reaction mechanism that has the necessary kinetics (reactions) for auto-ignition, and also use the species transport model with "Finite-Rate/No TCI" option.

       

    • Mathieu G
      Subscriber

      Hi Ren,

      Thank you for your answer. I'll try with the Finite Rate/No TCI model.

      Do you have any idea why i'm having a negative HRR when using partially premixed combustion models ?

      Thanks ! 

Viewing 2 reply threads
  • The topic ‘Transient FGM (Ignition and Heat Release Rate)’ is closed to new replies.