how to predict Equivalence ratio contours
 

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.

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?

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!

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