underexpanded jet with partially premixed model
 

Hello,

I'm quite new to the combustion models available in Fluent, and I'm currently trying to simulate an underexpanded jet of hydrogen inside a constant volume chamber, to ignite it after the injection is over. I'm using the partially premixed model, with steady diffusion flamelet (c equation).

I have noticed that during the injection the underexpanded jet is not properly resolved. Where the mixture fraction is equal to 1, as in the core flow, temperature is fixed to 300 K and density is wrong too. Basically I cannot reproduce none of the shocks and expansions featuring the jet. To my understanding, with the combustion model activate temperature and density are evaluated by using the tabulated data, instead of being calculated by mass and energy equations. This might explain the strange behavior I'm observing.

Any suggestions? Is there the possibility to properly solve the jet with the combution model on?

Thanks!