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Problem of ignition comparison between V2.4 and V3.0

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Old   June 17, 2020, 22:37
Default Problem of ignition comparison between V2.4 and V3.0
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By comparing the ignition between CONVERGE 2.4 and 3.0, I found a problem as follows.

Since 'source.max_value' in 'source.in' must be less than 5000K in V3.0 compared with 50000K in V2.4, the ignition delay in V3.0 is much slower than that in V2.4, so is the combustion process. This phenomenon is much serious in high speed condition like 5500rpm/WOT, which causes a bad result of misfire in V3.0. (Source type is energy)

How to solve this problem?

Last edited by Henrylyd; June 18, 2020 at 01:40.
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Old   July 3, 2020, 09:50
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Hi Liu, Depending on the problem, the maximum temperature in source.in can be adjusted. Higher maximum temperatures can help with quicker combustion propagation. However, the high gradient of temperature at cell points should be monitored.



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Originally Posted by Henrylyd View Post
By comparing the ignition between CONVERGE 2.4 and 3.0, I found a problem as follows.

Since 'source.max_value' in 'source.in' must be less than 5000K in V3.0 compared with 50000K in V2.4, the ignition delay in V3.0 is much slower than that in V2.4, so is the combustion process. This phenomenon is much serious in high speed condition like 5500rpm/WOT, which causes a bad result of misfire in V3.0. (Source type is energy)

How to solve this problem?
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Convergent Science, Inc.
Madison, WI, USA
www.convergecfd.com
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Old   July 5, 2020, 22:07
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Quote:
Originally Posted by Pedram Tazraei View Post
Hi Liu, Depending on the problem, the maximum temperature in source.in can be adjusted. Higher maximum temperatures can help with quicker combustion propagation. However, the high gradient of temperature at cell points should be monitored.
Dear Tazraei,
The problem is, 'source.max_value' in 'source.in' must be less than 5000K in V3.0, or the program doesn't start up. With this small temperature setting, the phenomenon of misfire often happens in condition of 5500rpm/WOT. How to solve this problem?
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Old   July 6, 2020, 10:41
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Hi Liu, thank you for your question. The user should be able to input a desired value for the max_value not limited to 5000K. As I mentioned in the previous post, the high gradient of temperature in cells might cause your simulation to crash. Your log file should help us find out the error you get. So please contact our support team at support@convergecfd.com.



Quote:
Originally Posted by Henrylyd View Post
Dear Tazraei,
The problem is, 'source.max_value' in 'source.in' must be less than 5000K in V3.0, or the program doesn't start up. With this small temperature setting, the phenomenon of misfire often happens in condition of 5500rpm/WOT. How to solve this problem?
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Pedram Tazraei, Ph.D.
Research Engineer
Convergent Science, Inc.
Madison, WI, USA
www.convergecfd.com
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Old   July 6, 2020, 21:05
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Quote:
Originally Posted by Pedram Tazraei View Post
Hi Liu, thank you for your question. The user should be able to input a desired value for the max_value not limited to 5000K. As I mentioned in the previous post, the high gradient of temperature in cells might cause your simulation to crash. Your log file should help us find out the error you get. So please contact our support team at support@convergecfd.com.
Dear Tazraei,
Thanks very much for your support. Actually, the problem I encounter is that, unlike in V2.4, when I simulate the combustion process of ICE 5500rpm/WOT in V3.0, it often misfires. In my experience, the reason may be the limitation of max_value 5000K. By the way, I also tried passive as the source, which didn't help.
I know the high temperature gradient will cause 'temperature exptrapolating...' issue, but it is not the problem I face. There is no error in log file.
So if I use G-equation model, how do I solve this misfire problem in 5500rpm/WOT?
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