how to predict Equivalence ratio contours

Ramon Quiñonez · November 28, 2018, 06:42

Hello all,

I have been working with pre-combustion simulation and I need to plot some plots of equivalence ratio in my simulated combustor on CFX. However I can't find a correct way to do it, since everytime I try I receive the same warning message

WARNING 'Vertex' values for Variable 'Eq rat' do not exist on Geometry /PLANE:Plane 1

I am using propane-air for a half stoichiometric condition, I have set up equations considering mass fraction, molar concentrations etc.

I have set Stoich A/F for propane of 15.6, but once I set up the actual A/F the warning appears again.

I really hope you can help me with this.

Many thanks.

ghorrocks · November 28, 2018, 16:58

You would need to provide more information for us to help.

Is this is CFD-Post or the solver? How are you setting up the equiv ratio variable? How have you set up the plane? How are you trying to do the plot?

Ramon Quiñonez · November 29, 2018, 11:41

Hello ghorrocks thanks for our reply, I am in POST, I am trying to plot the contours in a plane, the equivalence ratio is

ER= stoichiometricAF/actual AF

but CFX gives mass fractions or molar concentrations, I found out a way of doing it by setting the equation (1/max(C3H8.Mass Fraction,0.0000001)) for the AF ratio and then just dividing by the stoich AF.

since F/A+F = mass fraction, then 1/(a/f)+1 =mf

Many thanks!

ghorrocks · November 29, 2018, 18:33

Are you sure your equations are correct? Isn't the AF ratio simply mf.air/mf.fuel?

November 28, 2018, 06:42	how to predict Equivalence ratio contours	#1
Ramon Quiñonez New Member José Ramón Quiñonez Arce Join Date: Oct 2017 Location: Leeds, UK Posts: 17 Rep Power: 8	Hello all, I have been working with pre-combustion simulation and I need to plot some plots of equivalence ratio in my simulated combustor on CFX. However I can't find a correct way to do it, since everytime I try I receive the same warning message WARNING 'Vertex' values for Variable 'Eq rat' do not exist on Geometry /PLANE:Plane 1 I am using propane-air for a half stoichiometric condition, I have set up equations considering mass fraction, molar concentrations etc. I have set Stoich A/F for propane of 15.6, but once I set up the actual A/F the warning appears again. I really hope you can help me with this. Many thanks.

November 28, 2018, 16:58		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,705 Rep Power: 143	You would need to provide more information for us to help. Is this is CFD-Post or the solver? How are you setting up the equiv ratio variable? How have you set up the plane? How are you trying to do the plot? __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

November 29, 2018, 18:33		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,705 Rep Power: 143	Are you sure your equations are correct? Isn't the AF ratio simply mf.air/mf.fuel? __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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November 29, 2018, 11:41		#3
Ramon Quiñonez New Member José Ramón Quiñonez Arce Join Date: Oct 2017 Location: Leeds, UK Posts: 17 Rep Power: 8	Hello ghorrocks thanks for our reply, I am in POST, I am trying to plot the contours in a plane, the equivalence ratio is ER= stoichiometricAF/actual AF but CFX gives mass fractions or molar concentrations, I found out a way of doing it by setting the equation (1/max(C3H8.Mass Fraction,0.0000001)) for the AF ratio and then just dividing by the stoich AF. since F/A+F = mass fraction, then 1/(a/f)+1 =mf Many thanks!