Learning Forum

[Mathieu G]

Hi,

I'm trying to model a battery during thermal runaway including the combustion of the vented gas. When running a non-reactive model, the thermal abuse model is running fine :

 

Heat Generation due to thermal abuse reaction profile :

When adding the partially premixed combustion model, heat generation from the thermal abuse is divided by ~100 :

I'm running on Fluent 2023R2, using the CHT Coupling Battery Model with thermal abuse and the partially premixed combustion model with the Flamelet Generated Manifold.

What could be the reason for such a change in behavior ?

Thanks for your help.

 

[Murari Iyengar]

Hi, the two models you are using are incompatible with each other.

[Mathieu G]

Hi ! Thanks for the anwser,

Can you provide more information on that ?

What is incompatible ? Battery Modelling and Modelling combustion with reduced order (Non-Premixed Combustion and (Partially) Premixed Combustion) or only the thermal abuse part with combustion ?

Thank you !

[Murari Iyengar]

The thermal abuse model is incompatible with combustion model.

[Mathieu G]

Is there a particular reason for this incompatibility ?

According to some quick tests, the thermal abuse model is running fine with finite-rate chemistry

[Murari Iyengar]

More specifically, the Battery Model is not compatible with the FGM combustion model. The heat sources from the Battery model are not properly accounted for in the FGM model. Hence, the skewed results. 

[Mathieu G]

Hi, thank you for the clarification !

Is this the case for all reduced order combustion model (Non Premixed and Partially Premixed with Chemical Equilibrium or Steady Diffusion Flamelets) ?

Adding a heat source without using the battery model would solve the issue or is it related to the treatment of solid zones when using FGM ?

 

 

[jcooper]

The incompatibility is due to the fact that combustion models and the thermal abuse model solve different energy equations.