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ECFM 3Z combustion problem

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Old   July 27, 2016, 04:05
Post ECFM 3Z combustion problem
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Hello,

Im trying to simulate a mixture formation and after that a combustion of this mixture in ProStar (only in ProStar). My problem appears when the mixture formation is completed: Mz combustion/ignition doesnt seem to work.
I defined it in the Advanced -> IC-Setup and selected the ECFM-3Z combustion model. I also defined the fuel and its octane number and all the rest, that is possible in the sections "Analysis Setup" and "Combustion".
The problem is now, that the combustion/ ignition doesnt seem to work properly, because I cant see any temperature or pressure rising.
In my output window I also see the message: "Developement of flame kernel at spark=1 i=2.27095E-04".
Does this message mean, that my flame kernel kernel is now 2.27E-04 m big?
How is it possible to make the flame kernel bigger so that I can see a pressure and temperature rising?

Any suggestions are appreciated!

Regards
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Old   July 28, 2016, 06:19
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hi,

I am not sure that it helps. but maybe you can double-check the hole diameter of injector. as far as ı remember you should define the hole diameter as m, not mm.
Just an idea.


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Originally Posted by Bücherknopf View Post
Hello,

Im trying to simulate a mixture formation and after that a combustion of this mixture in ProStar (only in ProStar). My problem appears when the mixture formation is completed: Mz combustion/ignition doesnt seem to work.
I defined it in the Advanced -> IC-Setup and selected the ECFM-3Z combustion model. I also defined the fuel and its octane number and all the rest, that is possible in the sections "Analysis Setup" and "Combustion".
The problem is now, that the combustion/ ignition doesnt seem to work properly, because I cant see any temperature or pressure rising.
In my output window I also see the message: "Developement of flame kernel at spark=1 i=2.27095E-04".
Does this message mean, that my flame kernel kernel is now 2.27E-04 m big?
How is it possible to make the flame kernel bigger so that I can see a pressure and temperature rising?

Any suggestions are appreciated!

Regards
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Old   July 28, 2016, 06:26
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Thanks for your reply!

But my problem is not the injector, because I can inject the fuel without any problems.
My problem is the ignition of the methane(fuel). The flame kernel is maybe too small or not powerfull enough to make the temperature and pressure rising.
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Old   July 28, 2016, 06:38
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let's think together then!

Basically, rate of injection, quantity of injected fuel, injection delay effect the combustion, right?
maybe you can check your injection data which includes start of injection and injected fuel.
you can try to change start of injection or quantity of injected fuel.

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Originally Posted by Bücherknopf View Post
Thanks for your reply!

But my problem is not the injector, because I can inject the fuel without any problems.
My problem is the ignition of the methane(fuel). The flame kernel is maybe too small or not powerfull enough to make the temperature and pressure rising.
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Old   July 28, 2016, 08:28
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I dont understand why we should look at the injector.
Also I have no injector defined.
In my case I define a velocity-boundary and it works quiet well.

Also I simulate first the injection, which works quiet good and second I want to simulate the combustion.

But the combustion doesnt seem to work because the ignition is not working.

Or do you think the ignition doesnt start because there is an inappropriate amount of fuel?
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Old   July 28, 2016, 08:36
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I have never done a simulation without injector for combustion before. So I couldn't understand your case.
But yes, I think there is no enough fuel for combustion, or no appropriate environment to start the combustion (temperature, pressure etc).

Quote:
Originally Posted by Bücherknopf View Post
I dont understand why we should look at the injector.
Also I have no injector defined.
In my case I define a velocity-boundary and it works quiet well.

Also I simulate first the injection, which works quiet good and second I want to simulate the combustion.

But the combustion doesnt seem to work because the ignition is not working.

Or do you think the ignition doesnt start because there is an inappropriate amount of fuel?
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Old   July 28, 2016, 08:42
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The temperature with 500K and the pressure with 30 bar should be fine for a combustion?

The massfraction of the CH4 is between 5%and 10% so it should do a combustion doesnt it?

lamda=1 for CH4 is about CH4=5%.
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Old   July 28, 2016, 08:54
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for diesel engines, lamda shouldn't be lower than 1,4.
maybe you can try to run your simulation when lamda is 1.5.

other parameters look ok.

but for gasoline engines, lamda can be 1.


Quote:
Originally Posted by Bücherknopf View Post
The temperature with 500K and the pressure with 30 bar should be fine for a combustion?

The massfraction of the CH4 is between 5%and 10% so it should do a combustion doesnt it?

lamda=1 for CH4 is about CH4=5%.
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Old   September 2, 2016, 04:48
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Hello its me again.

I tried a very easy setup now: no boundaries, only a chamber with 5%-CH4, 21%-O2 and the rest N2.
I started with 500K and 8 bar pressure.
I used the ECFM-3Z,spark and tried all three ignition models (Standard,AKTIM,ISSIM).
The result was always the same: I never got an ignition and no combustion.

I dont understand where the problem is?
Any suggestions would be helpful!
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Old   February 9, 2017, 04:30
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I deal with the same problem. kindly help.
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Old   February 9, 2017, 08:24
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I'm simulating similar stuff with es-ice, where its possible to set a timing for the spark ignition. Have you checked the timing? greets
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Old   February 16, 2017, 08:35
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Yes. Did check the timings. But its not initiating.
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