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'Tot_Inj_Mass' decrease

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Old   January 31, 2021, 22:06
Default 'Tot_Inj_Mass' decrease
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liang11
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Hello, everyone!
I am working on water direct injection on a SI engine. In one case, the water mass and injection duration are respectively set as 5.1 mg and 2.2 °CA. And the setup of the spray model is similar to GDI spray.
However, the total injection mass decreases near the end of injection, even lower than the liquid spray mass. I don't know why?

Besides, if the water mass and injection duration increase, the problem may not exist.

I really appreciate your help!
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Old   February 3, 2021, 13:51
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Quote:
Originally Posted by liang11 View Post
Hello, everyone!
I am working on water direct injection on a SI engine. In one case, the water mass and injection duration are respectively set as 5.1 mg and 2.2 °CA. And the setup of the spray model is similar to GDI spray.
However, the total injection mass decreases near the end of injection, even lower than the liquid spray mass. I don't know why?

Besides, if the water mass and injection duration increase, the problem may not exist.

I really appreciate your help!
Hello!

There are a few simple things we should check before we get into deep details. First, confirm that you are using output files from the same run. I know it seems silly, but many people make this mistake (including myself, before).

Second what version of CONVERGE are you running? If it's not 3.0.19, I would try running this case again with the latest version downloaded from our website - see below for a link

Thanks,

- John
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Old   February 3, 2021, 21:44
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Originally Posted by jetcheve View Post
Hello!

There are a few simple things we should check before we get into deep details. First, confirm that you are using output files from the same run. I know it seems silly, but many people make this mistake (including myself, before).

Second what version of CONVERGE are you running? If it's not 3.0.19, I would try running this case again with the latest version downloaded from our website - see below for a link

Thanks,

- John
Hi!
The time interval set for text output around spray injection is 0.1 °CA, and the real output crank angle on both sides of the 'decrease' is respectively -177.49978 °CA ATDC and -177.37828 °CA ATDC, and the real timestep is about 3.7e-06 second (1000 RPM).
And the injection duration is set as 2.6 °CA instead of 2.2 °CA,I make a mistake before. Also, the injection is started at -180 °CA ATDC.

And I am using the Converge V2.4, are there any differences between V2.4 and 3.0.19? If using a different Converge version, is the result will be different?
And I don't see any link.

Thank you! I appreciate your help!
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Old   February 4, 2021, 16:02
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Originally Posted by liang11 View Post
Hi!
The time interval set for text output around spray injection is 0.1 °CA, and the real output crank angle on both sides of the 'decrease' is respectively -177.49978 °CA ATDC and -177.37828 °CA ATDC, and the real timestep is about 3.7e-06 second (1000 RPM).
And the injection duration is set as 2.6 °CA instead of 2.2 °CA,I make a mistake before. Also, the injection is started at -180 °CA ATDC.

And I am using the Converge V2.4, are there any differences between V2.4 and 3.0.19? If using a different Converge version, is the result will be different?
And I don't see any link.

Thank you! I appreciate your help!
Hello again!

Sounds like you are using the correct files.

Since you are using 2.4 I would not use 3.0.19. Instead when you login (click the CONVERGECFD link in my signature) to our downloads site download the latest version of 2.4 and try running your simulation with that.

Thanks!

- John
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