[Sahus]

Hello Everyone,
I ran simulation of GDI engine of Example Case in CONVERGE with my own valve lift profiles, ignition and injection timings and subsequently Combustion timings. I didn't use AMR for the 1st time to save time. the maximum pressure was about 22 bar and when I tried to calculate the Engine Performance from engine performance calculator tool, it showed NO WORK OUTPUT- NOT ENOUGH DATA.


for the second time I used AMR, but again the pressure curve is exactly the same.
Used fixed embedding both the times. Base grid size 4mm



I didn't change the ignition energy i.e. I used 0.02J for 0.5 CAD and 0.02J for 15 CAD. I used the reaction mechanism that provided in CONVERGE Example case itself.


Where should I look to ensure there is a work output/Combustion?


Thanks and Regards
Saket

[MFGT]

Hi,


how is the equivalence Ratio? Do you have spark embedding?

Whats the temperature?


So you basically only exchanged geometry and modified valve lifts, spark timing, injected fuel mass?

[Sahus]

Originally Posted by MFGT

Hi,


how is the equivalence Ratio? Do you have spark embedding?

Whats the temperature?


So you basically only exchanged geometry and modified valve lifts, spark timing, injected fuel mass?

Hello,

I used equivalence ratio of 1. Yes, I did have 2 spark embeddings for both ignition stages.

By temperature if you mean in-cylinder temperature, than Max mean in-cylinder is coming out to be 700 K without AMR and 736 K with AMR ( MAX TEMPERATURE is 46600 K at the spark timing)

Basically I modified values which requires CAD values, like valve lifts, spark timing, injection timing, events etc. I even let amount of fuel injected as it is.

[MCoil]

Hi -


Since you changed some things, it might be worth sending your case to support@convergecfd.com. First try doing a little digging.


So one good way to monitor your simulation while it's running is to look at the text output files. You can view them in the CONVERGE Studio line plotter or using something like gnuplot. So look at thermo_regionx.out, where x is the number of the engine cylinder region (typically 0). Here, look at the maximum temperature to see if you're starting to get combustion. Look at the heat release rate to see if the combustion is releasing any energy. You can of course look at the cylinder pressure (as you have plotted). Also look at the species_mass_fraction_region0.out. Look for markers of ignition like CH2O and OH. See if those are getting produced.


Another thing to do is to look at the 3D data. Here, I'd look over the whole domain to see that you have good grid resolution where you want it. Look around the spark. Are you seeing your embedding? If you changed the timing of the spark, did you also change the timing of the embeddding? Do you see an intense, high temperature region by the spark? In the chamber, you'll need about 0.5 mm (or smaller) cells to resolve the combustion.


The error you see with the engine performance calculator has to do with it not seeing the proper range of crank angle degrees over which to do the calculation. Check your start/stop settings and what you set for the CAD at TDC.


If you don't see the problem, then please email support.


Thank you!