engineFoam - Low temperature/no combustion

Zniacs · October 26, 2020, 10:07

Hello,

I'm running an engineFoam case using a skeletal mechanism for diesel with NOx formation (133 species and 1058 reactions) and it seems that no combustion is happening.

In order to simplify the simulation I'm using a simple cylinder, meshed in Salome, completely hexahedral and engCompRatio gives a 17.9995 return.

In one of my atempts of running a case with P1 radiation model, the max gas T @0deg was 629K. The case I'm running at this moment has a 505K max T @-3deg with no radiation model.

I have no idea why the combustion is not happening, chemistry is on and combustion is active.

Thank you in advance.

Zniacs · October 26, 2020, 15:22

Okay, I did a bit of investigating by running a aachenBomb tutorial using the chemkin files from the engineFoam case.

I figured it out that I have a problem with the liquid properties. The liquid temperature goes up a lot, while the gas temperature stays constant, which seems to me as an error in the boiling point of the liquid mixture I'm using.

I'm defining the liquid mixture in the file sprayCloudProperties as:

singlePhaseMixtureCoeffs
{
phases
(
liquid
{
C10H22 0.3;
aC11H10 0.7;
}
);
}

liquidEvaporationBoilCoeffs
{
enthalpyTransfer enthalpyDifference;
activeLiquids (C10H22 aC11H10);
}

And in the thermophysicalPorperties:

liquids
{
C10H22;
aC11H10;
}

Is this syntax correct?

October 26, 2020, 10:07	engineFoam - Low temperature/no combustion	#1
Zniacs New Member Jorge Sá Join Date: Aug 2020 Posts: 2 Rep Power: 0	Hello, I'm running an engineFoam case using a skeletal mechanism for diesel with NOx formation (133 species and 1058 reactions) and it seems that no combustion is happening. In order to simplify the simulation I'm using a simple cylinder, meshed in Salome, completely hexahedral and engCompRatio gives a 17.9995 return. In one of my atempts of running a case with P1 radiation model, the max gas T @0deg was 629K. The case I'm running at this moment has a 505K max T @-3deg with no radiation model. I have no idea why the combustion is not happening, chemistry is on and combustion is active. Thank you in advance. Last edited by Zniacs; October 28, 2020 at 10:15.

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October 26, 2020, 15:22		#2
Zniacs New Member Jorge Sá Join Date: Aug 2020 Posts: 2 Rep Power: 0	Okay, I did a bit of investigating by running a aachenBomb tutorial using the chemkin files from the engineFoam case. I figured it out that I have a problem with the liquid properties. The liquid temperature goes up a lot, while the gas temperature stays constant, which seems to me as an error in the boiling point of the liquid mixture I'm using. I'm defining the liquid mixture in the file sprayCloudProperties as: singlePhaseMixtureCoeffs { phases ( liquid { C10H22 0.3; aC11H10 0.7; } ); } liquidEvaporationBoilCoeffs { enthalpyTransfer enthalpyDifference; activeLiquids (C10H22 aC11H10); } And in the thermophysicalPorperties: liquids { C10H22; aC11H10; } Is this syntax correct?