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-   -   Reflection of acoustic disturbances Outlflow from the backflow pressure (https://www.cfd-online.com/Forums/converge/210605-reflection-acoustic-disturbances-outlflow-backflow-pressure.html)

abdellahcfd October 31, 2018 03:19

Reflection of acoustic disturbances Outlflow from the backflow pressure
 
Hi,

From a comparaison with a multi-cylinder GT calibrated model, I am having some issues that I suspect are from the acoustics.

I start the simulation on CV (-230 to 490 1-Cylinder), and during the Exhaust I seem to not match at all the GT pressure.
Do you have any idea on how can I calibrate these disturbances ?

Tke intensity ? Eps length scale ?

Regards
Abdellah

dprobst October 31, 2018 15:13

Quote:

Originally Posted by abdellahcfd (Post 713632)
Hi,

From a comparaison with a multi-cylinder GT calibrated model, I am having some issues that I suspect are from the acoustics.

I start the simulation on CV (-230 to 490 1-Cylinder), and during the Exhaust I seem to not match at all the GT pressure.
Do you have any idea on how can I calibrate these disturbances ?

Tke intensity ? Eps length scale ?

Regards
Abdellah


Hi Abdellah,
I'd like to know more to be sure to give you a good answer but in general, it should be fairly easy to model the acoustic phenomena in CONVERGE to match GT, but you need to consider the timesteps and boundary conditions, as well as letting the system wash out initial conditions. The turbulence model is probably not an issue. If you are looking at pressure waves, you need to consider the dt_mach CFL limiter in CONVERGE.

Additionally, capturing the same phenomona of a multi cycle engine may not be possible in a single cylinder configuration.

I would suggest you contact our support team for specific help on your model.

abdellahcfd November 5, 2018 05:32

Thanks for the indications Dan ! I will do.

I had better results when I imposed in the Inflow/Outlow the Pressure/Temperature profiles over time (I was using an average for now). But still a few differences, probably due to multi-Cylinder / 1-Cylinder difference

Regards
Abdellah


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