Modeling of flame-wall interaction for combustion and heat transfer in S.I. engines

A numerical combustion model was developed for an engine CFD code in spark ignition engine combustion chambers. The combustion model features the following new concepts: (1) The introduction of preheated reactants which are produced in the turbulent mixing process and consumed in the reaction process; (2) the modification of the probability of burned and unburned gas blobs meeting each other in consideration of a change in turbulence length scale, which becomes smaller in the near wall region. With the first concept, the model deals with turbulence-reaction controlled combustion in the near wall region as well as turbulence-controlled combustion in the core region. The second concept avoids the unrealistic flame shape due to the near wall acceleration of the turbulent flame propagation, which is inherently seen in combustion models based simply on the turbulent mixing time such as the Magnussen model. It is also shown that the present model gives more realistic local heat fluxes.