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-   -   Combustion problem in STAR CD... help me, please! (http://www.cfd-online.com/Forums/star-cd/68295-combustion-problem-star-cd-help-me-please.html)

mrkokoko September 14, 2009 06:13

Combustion problem in STAR CD... help me, please!
 
Hi, ladies and gentlemen...
I'm using STAR CD Ver. 3.26 and model of 4valve gasoline engine geometry.
By the way..there may be some problems about combustion setting.
The cylinder pressure (region 1 pressure) is peak just 8bar..
In experiment, cylinder pressure is about 18~20bar in the same operation condition.
I used iso-octane model
I used CFM model, and premixed intake mixture.
Kernel diameter was setted in 4mm.
delay time was setted with 0.00068sec.
And Fraction factor was setted in 0.64.

I don't know where the problem is... :)

By the way..
I have some questions

1) Fuel percentage in intake port from esice's star control is linked to mass fraction of C8H18 in prostar?
2) I think that the combustion is not operated.. flame core is not located in the location where i setted. Highest temperature is located in the crevice.. But the highest temperature is just 600K... I'm not sure whether combustion is occured.

Is there anyone who have the same case of me?
Please let me know the method to solve this problem.
Have a nice day, handsome guys! :)

From a poor guy in South Korea

cfdvenkatesh September 14, 2009 17:00

Combustion Problem
 
Please check the Crank Angle of peak pressure between your model and experiment. You can adjust the parameters in CFD you match 50% duration of your model and experiment. (It is like calibrating your CFD model with experiment).


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