Instability in Combustion Modelling (Detailed Chemical Mechanism + DOM-SNBCk)
 

Hello Folks,

This is my first post, so a little introduction. Im pursuing my PhD in France on combustion modelling field, specifically soot production.

Now my problem, the context... Today Im modelling a Laminar Boundary Layer Diffusion Flame, you will see images, by using a CFD code in FORTRAN, for pressure-velocity Im using SIMPLE model (Patankar), for chemical Im using CHEMKIN with a detailed chemical kinetics mechanism (Slavinskaya_Combust. Flame 156:1705-1722 (2009)) and radiation by solving radiative transfer equation via Discrete Ordinate Method coupled to a statistical narrow-band-correlated K (SNBCK)-based wide-band model for properties of CO, CO2, and H2O.

The parameters we are varying are Vox (oxidizer velocity) and Vf (fuel injection velocity).

Normally, everything is good when we use Vox 300 mm/s and 250 mm/s, but when we down under 250, for example 200 mm/s, an instability occurs in the trailing edge of burner (fuel injection zone), I've already tried by reducing timestep but it's not going better.

Can you try to advise me?