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Old   March 18, 2007, 11:08
Default combustion
  #1
selva
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can anyone tell me how to give equivalence ratio value in fluent. thanks in advance
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Old   March 21, 2007, 05:17
Default Re: combustion
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Zenith
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HI

Equivalence ratio value input depends on the type of combustion, one is trying to model. It offers following types of combustion models

Premixed combustion

Non premixed

Partially premixed

What type of model You are using.

zenith mark
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Old   March 21, 2007, 11:14
Default Re: combustion
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selva
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hi, i am modeling premixed combustion with an equivalence ratio of 4.4. i know the air and fuel velocity and i have given the value at the boundary condition along with the species mass fraction. then where we have to specify the equivalence value? or equivalence ratio is used to find air and fuel velocity? plz reply thanks
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Old   March 22, 2007, 03:41
Default Re: combustion
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zenith
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HI

For premixed combustion, species transport equations are not solved. Fluent solves the equation for mean progress variable'c'. Hence species in there elemental compostion remain conserved for premixed combustion. So we are left with the conservation of energy, how Fluent does it.

Dear if you are using premixed combustion model then there are two possiblities

1) adiabetic

In adiabetic premixed combustion, energy equation is not solved. Temperature of mixture is calculated from the temperature of inlet mixture and adiabetic flame temperature. Fluent assumes or fits a linear approximation bewteen these two temperature limits.

2) nonadiabetic

in non adiabetic premixed combustion, energy equation is solved, so two informations are needed, first heat of combustion and the other is mass fraction of unburnt fuel

It is the second parameter " mass fraction of unburnt fuel" in inlet stream which is calculated from equivalence ratio.

Mass fraction apperas in the material properties of mixture. Defining this parameter means that you are defining the equivalence ratio. You will not see this parameter it modeling adiabetic system

Hope this answers your question

Zenith mark
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Old   March 23, 2007, 00:00
Default Re: combustion
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selva
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thanks ya, i am using adiabatic condition. from ur answer i feel that i am in correct path. thanks a lot
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