Hi everybody

I have to simulate combustion in a diesel engine. On Star manual I can read that the Laminar and turbulent characteristic time model, that is a variation of the Magnussen model, is the recommended model for this kind of simulation. Has anyone used it? Why should it perform better that the PPDF model?

Hi,

Diesel combustions doesn't work like a premixed SI-engine combustion. Due to the coexistent appearance of liquid fuel entrainment, mixture formation, ignition and combustion the whole combustion process is seen as mixing controlled. Combustion can only occour if air (=O2) and fuel vapour can come together. The speed of this "comming together" is proportional to the combustion rate because the chemical kinetic oxidation of the fuel with O2 is much faster then the mixing of the species. So the Magnussen model does account for the speed of this mixing process. The LATCT model additionaly does account for special effects in the near wall and spray regions.

Hope this helps, Franz