CFD Online Discussion Forums - Ignition in combustion

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Ignition in combustion

Hi Foamers

How can we provide an ignition source in combustion which lasts for only few seconds till the charge ignites.

I have tried setting high temperature for internal field but the flame just ignites on entry itself. Is there a way to give high temperature patch?

You can use a volumetric heat source for creating high temperature patch using fvOptions or setFieldsDict. Time of ignition can be mentioned there.

As an example:

fvModels (since OFv9 )

Code:

ignition

{

    type             heatSource;//semiImplicitSource;

    selectionMode    cellSet;

    cellSet            ignition;

    volumeMode        absolute; //absolute



    q 

    {

        type scale;

        scale squarePulse;

        start 0.0005;

        duration 0.001;

        value 1e+8;

    }

    /*sources

    {

        Qign

        {

            // type             semiImplicitSource;

            // name             heatInjection;

            // selectionMode     cellSet;

            // cellSet         ignition;

            // volumeMode        specific;

            // timeStart        0.001;

            // duration        0.01;

            explicit 10e+7;

            implicit 0; //{}

        }

    }*/

}

and topoSetDict

Code:

actions

(

    {

        name ignition;//ignitionCells;

        type cellSet;

        action new;



        source cylinderToCell; // or whatever

        sourceInfo

        {

            p1          (x y z);

            p2            (x y z);

            radius          1e-2; //outer radius

            innerRadius        0;    //default 0

        }

    }

);

Thankyou. the volumetric heat source idea worked. It was given using fvModels.(i am using openfoam dev, ofv9 should also have this. earlier versions it was under a file called fvOptions)