multi-fuel case can't ignition

luckyboy · September 25, 2017, 10:07

Hello,

In my case, I use the mixture of biodiesel and diesel as the fuel, but there are some trouble which cause the heat relase rate is negative, as the attachment show. The 1.zip file in attachments is the input fule and the cvg.zip is the .cvg file. please some can help me and find what problem there is.

Thanks!

MRaza · September 25, 2017, 23:20

Hello!

I am using multi-component surrogate fuels for gasoline and diesel for my RCCI dual fuel simulation. And I am also getting the negative heat release rate and even pressure rise rate is very low.

Hope someone could address this issue.

Thank you!

luckyboy · September 25, 2017, 23:27

Hi, MRaza
Do you look the evaporation result? In my result, the evaporation mass is very less. So I think the main problem results from the evaporation model.
Thank you!

luckyboy · September 26, 2017, 06:42

Quote:

Originally Posted by MRaza

Hello!

I am using multi-component surrogate fuels for gasoline and diesel for my RCCI dual fuel simulation. And I am also getting the negative heat release rate and even pressure rise rate is very low.

Hope someone could address this issue.

Thank you!

Hello,
I have sloved the problem. You can try to increase the total number of injected parcels(per nozzle) to 200000 even bigger. When I set the valve to 200000, the trouble is sloved.

MRaza · September 28, 2017, 02:43

Quote:

Originally Posted by luckyboy

Hello,
I have sloved the problem. You can try to increase the total number of injected parcels(per nozzle) to 200000 even bigger. When I set the valve to 200000, the trouble is sloved.

Thanks for your suggestion. I have tried increasing the total parcels to 300,000 but the problem is still unresolved.

MFGT · September 28, 2017, 03:01

@luckyboy:
I think your mixture is way too rich.
The specifed fuell mass should only be the one injected into that sector.

With current settings (post1), your mass per parcel was 43e-6kg/50000parcels = 8.6e-10kg/parcel
Rumors say, this value should be in the range of 2e-10kg/parcel.

Furthermore your nozzle diameter and circular injection radius do not match.

luckyboy · September 28, 2017, 06:13

Quote:

Originally Posted by MFGT

@luckyboy:
I think your mixture is way too rich.
The specifed fuell mass should only be the one injected into that sector.

With current settings (post1), your mass per parcel was 43e-6kg/50000parcels = 8.6e-10kg/parcel
Rumors say, this value should be in the range of 2e-10kg/parcel.

Furthermore your nozzle diameter and circular injection radius do not match.

Thank you very much!

MFGT · September 30, 2017, 03:33

And by the way, when i downloaded the case and ran it with gridscale -2 (no other changes), i saw a reaction and had lots of heat release. So i wonder how you got your results?

Furhtermore, there were still lots of example case input data like initialization, spray rate profile etc.

Are you planning to do theoretical investigations or is your simulation based on a real engine + experiment data?

September 25, 2017, 23:20	RCCI dual fuel simulation	#2
MRaza New Member Mohsin Raza Join Date: Jun 2017 Posts: 6 Rep Power: 9	Hello! I am using multi-component surrogate fuels for gasoline and diesel for my RCCI dual fuel simulation. And I am also getting the negative heat release rate and even pressure rise rate is very low. Hope someone could address this issue. Thank you!

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September 25, 2017, 23:27		#3
luckyboy Member liyong Join Date: Feb 2017 Posts: 66 Rep Power: 9	Hi, MRaza Do you look the evaporation result? In my result, the evaporation mass is very less. So I think the main problem results from the evaporation model. Thank you!

September 28, 2017, 03:01		#6
MFGT Senior Member Tobias Join Date: May 2016 Location: Germany Posts: 283 Rep Power: 11	@luckyboy: I think your mixture is way too rich. The specifed fuell mass should only be the one injected into that sector. With current settings (post1), your mass per parcel was 43e-6kg/50000parcels = 8.6e-10kg/parcel Rumors say, this value should be in the range of 2e-10kg/parcel. Furthermore your nozzle diameter and circular injection radius do not match.

September 30, 2017, 03:33		#8
MFGT Senior Member Tobias Join Date: May 2016 Location: Germany Posts: 283 Rep Power: 11	And by the way, when i downloaded the case and ran it with gridscale -2 (no other changes), i saw a reaction and had lots of heat release. So i wonder how you got your results? Furhtermore, there were still lots of example case input data like initialization, spray rate profile etc. Are you planning to do theoretical investigations or is your simulation based on a real engine + experiment data?