[usamaubk]

Hello everybody, I am running a simulation of a simple diesel engine. MY simulated HRR seems to be rising really ahead of the EXP case. (see the image). I have used other SOI like SOI of 10 but that actually doesn't help. it decreases the first peak. I also tried to tweak other parameters like cd but in vain. So I need ideas on how to delay the CFD HRR(WM110.9) to match the experimental graph. any suggestions will be appreciated. Thanks

[asofianopoulos]

Hello Usama,
There are multiple reasons this can be happening. I would recommend updating your KH-RT model settings to our recommendation for Diesel engines (set recommendations for button in CONVERGE Studio) and update all of your spray settings based on our Engine Sector Diesel example case.
If that does not work, you can look at your fuel surrogate and the chemical kinetics mechanism that you use. You can contact us at support@convergecfd.com where we can discuss more about your case.
Thank you,

Best regards,


Aimilios Sofianopoulos, Ph.D.
Senior Research Engineer - Applications
Convergent Science Inc.
608-230-1565 (Office)
631-488-5394 (Mobile)

[Eleven Leo]

Hello,

In my opinion, SOI can be retarded due to the time of needle lift, and the injection velocity profile should be set according to the experiment, which is also an important factor.
Of course, the constants of KH-RT model, and chemical mechanism also show the evident effects on ignition timing, as Dr. Sofianopoulos said.

Best
Yaopeng

Originally Posted by usamaubk

Hello everybody, I am running a simulation of a simple diesel engine. MY simulated HRR seems to be rising really ahead of the EXP case. (see the image). I have used other SOI like SOI of 10 but that actually doesn't help. it decreases the first peak. I also tried to tweak other parameters like cd but in vain. So I need ideas on how to delay the CFD HRR(WM110.9) to match the experimental graph. any suggestions will be appreciated. Thanks

[usamaubk]

Thanks for the suggestions and comments. These are really helpful ....actually, I found the problem, the problem was with the IVC temperature which was set too high, so by decreasing the temperature by app 10%, the Ignition delay was prolonged and the Simulated HRR actually matched the EXP HRR curve. So, the problem was IVC Temperature which was too high....