OpenWAM » Heat transfer coefficients

Heat transfer coefficients

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  • January 11, 2012 at 10:15 am #315
    Anonymous
    Inactive

    Hi,

    I was wondering to what these coefficients correspond :

    I searched in OpenWAM manual but I didn’t find anything.

    Does “CW” mean “Cylinder Wall” ?

    Thanks

    January 11, 2012 at 10:36 am #471
    sreenathiit12sreenathiit12
    Member

    Heat transfer fitting of intake coefficient and heat trasnfer fitting of exhaust coefficient are coefficients that multiply heat trasnfer during the intake and the exhaust proceses. By default you can use 1.

    Xpe is not used, is an old coefficient, you don’t need to put any specific value.

    CW1 and CW2 are coefficients of the Woshni equation. This equation determines the heat transfer cofficient between the gas and the cylinder walls. As default values you can use 1.7 for CW1 and 1 for CW2

    January 11, 2012 at 11:43 am #472
    sreenathiit12sreenathiit12
    Member

    You can find a better explanation of the coefficients CW1 and CW2 in SAE Technical Paper 2005-01-0210

    January 11, 2012 at 12:47 pm #473
    Anonymous
    Inactive

    Thanks.

    So in the Woshni equation :

    C1 & C2 correspond to CW1 & CW2?

    Because in the manual, it’s written that C2 is 3.24.10-3 or 6.22.10-3 depending on open or divided chamber, and C1 is 6.18+0.417*Cu/Cm or 2.28+0.308*Cu/Cm depending on the type of process (air management or compression/expension) ?

    January 11, 2012 at 4:10 pm #474
    sreenathiit12sreenathiit12
    Member

    In the last versión of OpenWAM

    C1=Cw1+Cw2*(Cu(alpha)/Vp)

    and

    C2=0.001

    January 13, 2012 at 7:41 am #475
    Anonymous
    Inactive

    Ok, thanks!

    November 5, 2014 at 7:15 pm #476
    matstral matstralmatstral matstral
    Member

    @farnau wrote:

    In the last versión of OpenWAM

    C1=Cw1+Cw2*(Cu(alpha)/Vp)

    and

    C2=0.001

    I have seen the Literautur. C1 should stand for 2 number。 one for gas exchange period: C1=6.18+0.417Cu/Cm ，and one for the rest: C1=2.28+0.308 Cu/Cm。 But in the Openwam we do not have two choice to define them for the different Phase。 So I want know, how would that be ? I will appreciate your answer！ Please help!

    November 6, 2014 at 7:49 am #477
    sreenathiit12sreenathiit12
    Member

    The values for the gas exchange period are internally defined (C1=6.18+0.417Cu/Cm). You must provide only the values for the rest of the period.

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