[sasanghomi]

Hi every body,

I have a problem with a case for coldFlow in an internal combustion engine (sonicTurbDyMEngineFoam )....the exhaust valve opens early (about 0.005 (s) ).Can any one help me????
How do I correct it???

thanks,
Sasan

[wyldckat]

Greetings Sasan,

Can you please provide more information? The reason I ask is because you're not providing enough information, as indicated in this thread: http://www.cfd-online.com/Forums/ope...-get-help.html

Best regards,
Bruno

PS: don't mind about the other post with strange characters, it was just a spammer...

[sasanghomi]

Hi wyldckat ,
Thank you very much.
I am running a case that it simulates the cold flow in an internal combustion engine.
The solver is sonicTurbDyMEngineFoam.The rotational velocity is (rpm=1500), So the total time for a cycle of the engine is 0.08(s).I expect that the exhaust valve opens at 0.06(s)
but when I plot the mass flow versus time at the exhaust port I saw that the exhaust valve opened at 0.055(s).How do I can correct this problem???please any one help me....

The engineGeometry is as below :

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM Extend Project: Open Source CFD        |
|  \\    /   O peration     | Version:  1.6-ext                               |
|   \\  /    A nd           | Web:      www.extend-project.de                 |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      engineGeometry;
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

conRodLength    conRodLength [0 1 0 0 0 0 0] 0.147;

bore            bore [0 1 0 0 0 0 0] 0.092;

stroke          stroke [0 1 0 0 0 0 0] 0.075;

clearance       clearance [0 1 0 0 0 0 0] 0.015;

rpm             rpm [0 0 -1 0 0 0 0] 1500;


engineTopoChangerMesh  simpleEngineTopoFvMesh;

// Between -deformAngle and deformAngle the piston motion is done
// using deformation and not layering
deformAngle     10;

valvePosTol     1e-4;

layeredMesh     yes;
checkMesh       yes;


piston
{
    patch               piston;

    coordinateSystem
    {
        type            cartesian;
        origin          (0 0 0);
        axis            (0 0 1);
        direction       (0 1 0);
    }

    minLayer        0.0005;
    maxLayer        0.001;
}

valveSplitPoint     (0.003 0 0);    // For the converter
// Two-valve engine valves are split on x
// Four valve engines are split into 4 quadrants in the x-y plane

valves
(
    intakeValve
    {
        // Valve coordinate system
        coordinateSystem
        {
            type            cylindrical;
            origin          (-0.025 0 0);
            axis            (0 0 1);
            direction       (0 1 0);
        }

        // Patch  and zone names
        bottomPatch             valve1;
        poppetPatch             valve2;
        stemPatch               valveStem1;

        curtainInPortPatch      valveCurtainPort1;
        curtainInCylinderPatch  valveCurtainCyl1;

        detachInCylinderPatch   valveDetachCyl1;
        detachInPortPatch       valveDetachPort1;

        detachFaces
        (
2593 
2595 
2597 
2599 
2601 
2603 
2605 
2607 
2609 
2611 
2613 
2615 
2617 
2619 
2621 
2623 
2625 
2627 
2629 
2630 
        );

        // Vertex on edge of the step.  For the converter
        stemEdge            (-0.04 0 -0.0075);

        // Valve diameter
        diameter            0.03;

        // Minimum valve lift
        minLift             0.00025;

        // Layer thickness
        minTopLayer         0.0005;
        maxTopLayer         0.001;

        minBottomLayer      0.0005;
        maxBottomLayer      0.001;

        // Lift Profile
        liftProfileFile "intakeLiftProfileFile";
    }

    exhaustValve
    {
        // Valve coordinate system
        coordinateSystem
        {
            type            cylindrical;
            origin          (0.025 0 0);
            axis            (0 0 1);
            direction       (0 1 0);
        }

        // Patch  and zone names
        bottomPatch             valve3;
        poppetPatch             valve4;
        stemPatch               valveStem2;

        curtainInPortPatch      valveCurtainPort2;
        curtainInCylinderPatch  valveCurtainCyl2;

        detachInCylinderPatch   valveDetachCyl2;
        detachInPortPatch       valveDetachPort2;

        detachFaces
        (
4854 
4856 
4858 
4860 
4862 
4864 
4866 
4868 
4870 
4872 
4874 
4876 
4878 
4880 
4882 
4884 
4886 
4888 
4890 
4891 
        );

        // Vertex on edge of the step.  For the converter
        stemEdge           (0.04 0 -0.0075);

        // Valve diameter
        diameter            0.03;

        // Minimum valve lift
        minLift             0.00025;

        // Layer thickness
        minTopLayer         0.0005;
        maxTopLayer         0.001;

        minBottomLayer      0.0005;
        maxBottomLayer      0.001;

        // Lift Profile
        liftProfileFile "exhaustLiftProfileFile";
    }

);

// ************************************************************************* //

An image of the case is attached.

Thanks,
Sasan.

[Peter_600]

The exhaust will open when the lift exhaust valve lift exceeds 0.0025 as specified in your dictionary.
So it depends on your valve lift profile.

cheers peter

[sasanghomi]

Thanks for your reply peter,

Can you give me any sources about describtion of minimum valve lift and valve lift profile??
Can you explain them??

thanks,
Sasan.

sasanghomi@yahoo.com

[enginejob]

hi, i have a problem with this solver too. The error is:

 --> FOAM FATAL ERROR: 
found boundary face in valve detach definition for valve 1.  This is not allowed.  Detach faces: 
24
(
12316
12317
12318
12319
12320
12321
12322
12323
12324
12325
12326
12327
12328
12329
12330
12331
12332
12333
12334
12335
12336
12337
12338
12339
)
 nInternalFaces: 12190

    From function void simpleEngineTopoFvMesh::addZonesAndModifiers()
    in file simpleEngineTopoFvMesh/addSimpleEngineTopoFvMeshModifiers.C at line 188.

Searching for this function i have found it:

// Create a detach zone
            if
            (
                valves_[valveI].detachInCylinderPatchID().active()
             && valves_[valveI].detachInPortPatchID().active()
             && valves_[valveI].detachFaces().size() > 0
            )
            {
                Info<< "Adding detach boundary for valve "
                    << valveI + 1 << endl;

                const vectorField& areas = Sf().internalField();

                const labelList& df = valves_[valveI].detachFaces();

                boolList flip(df.size(), false);

                const vector& pistonAxis = piston().cs().axis();

                forAll (df, dfI)
                {
                    if (isInternalFace(df[dfI]))
                    {
                        if ((areas[df[dfI]] & pistonAxis) > 0)
                        {
                            flip[dfI] = true;
                        }
                    }
                    else
                    {
                        FatalErrorIn
                        (
                            "void simpleEngineTopoFvMesh::"
                            "addZonesAndModifiers()"
                        )   << "found boundary face in valve detach definition"
                            << " for valve " << valveI + 1
                            << ".  This is not allowed.  Detach faces: "
                            << df << " nInternalFaces: " << nInternalFaces()
                            << abort(FatalError);
                    }
                }

probably i have some problems with the mesh, right ?
How do i do the mesh at the detach zone ?