AVL FIRE ESE Diesel piston simulation initial condition
 

Hi friends,

I am doing a piston bowl simulation study using AVL FIRE ESE Diesel simulation

I am starting the simulation from IVC and the BC and initial conditions will be taking from AVL boost simulation. The pressure& temp values can be taken from Boost output. How can we get the EGR mass fraction, EGR composition & Equivalent ratio values @ initial conditions. Plz suggest ur opinions based on ur experience

Following approach can be used to get an estimate of EGR mass fraction:
a) Run a BOOST simulation with the EGR cam profile and get a good correlation with the experimental results (good if you have experimental results). This will help you to validate the model
b) Run the same BOOST model without EGR cam profile and check for the air flow
c) EGR % is the amount of air flow change that you see by change in the cam profiles.

For eg, if it comes out to be as 12 % change in air flow , put the value as 0.12 in EGR mass fraction

This part covers your EGR mass fraction value.


Now for EGR composition:
a) Find the air to fuel ratio (AFR) and divide the value by 14.7 (i.e. Stoichiometric AFR), what you get is the equivalence ratio.
b) Take reciprocal value of equivalence ratio calculated above. This is EGR composition

For eg, if your AFR at 100% rated load and speed is 24 (say), then Equivalence ratio is 24/14.7 = 1.632 and reciprocal of this value = 0.6125
Hence EGR composition is 0.6125

Please note that all these calculations needs to be done for the load point which you want to simulate.

Hope this works for you...
Anyone please correct if anything is missed or seems incorrect...