how to predict Equivalence ratio contours

Ramon Quiñonez · November 28, 2018, 07:42

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, 17:58

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, 12:41

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, 19:33

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

November 28, 2018, 07:42	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: 9	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, 17:58		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	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, 19:33		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	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.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Problem with divergence	TDK	FLUENT	13	December 14, 2018 07:00
equivalence ratio of inlet mixture	Weiqiang Liu	FLUENT	7	October 5, 2018 00:36
pressure eq. "converges" after few time steps	maddalena	OpenFOAM Running, Solving & CFD	69	July 21, 2011 08:42
diesel spray combustion equivalence ratio	usker	Siemens	12	March 1, 2008 07:09
Mass removal and injection...Please help!	Kevin Till	Siemens	27	July 25, 2005 14:09

November 29, 2018, 12:41		#3
Ramon Quiñonez New Member José Ramón Quiñonez Arce Join Date: Oct 2017 Location: Leeds, UK Posts: 17 Rep Power: 9	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!