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The SI engine combustion model LI-CFM introduced by Boudier et, al. (1992) [8] is extended to deal with actual engines. New models are proposed to simulate ignition with convection at the spark and flame-wall interaction. The scalar properties of the unburnt gases within the combustion zone are computed. This allows for the computation of flame propagation in temperature, fuel and residual gas stratified charges. A model for NO and CO formation is introduced. It is based on a conditional burnt/unburnt averaging of the reaction rates. Pollutants are created at the flamelet level and evolve in the burnt, gases using a mixed equilibrium/kinetic scheme. All these physical models are implemented in a multi-block version of the Kiva 2 code, KMB. This code is used to simulate a 4-valve engine including intake ports. Initial and boundary conditions are obtained from a ID acoustic code.

A laser induced fluorescence (LIF) technique to visualize the gasoline distribution in port injection spark ignition engines is presented. A dopant is selected according to a list of criteria required to make it a good tracer of the gasoline. This dopant, biacetyl, is shown to provide quantitative measurement in relative value. The LIF technique is applied for two-dimensional laser sheet imaging in a model engine with optical access. Extensive data processing is developped and used for a quantitative characterization of the mixing level. The effect of compression, injection timing, engine speed, and type of flow field on the mixture homogeneity is investigated.

High speed Schlieren cinematography along with flame contour analysis is used to study the early flame propagation, from spark to a 4 mm flame radius. This is done for lean propane–air mixtures, and up to 1500 RPM. For normal engine speeds, the flame is turbulent immediatly after initiation, with no laminar phase. The burnt kernel is first driven by the electric ignition source. After about 0.5 ms, the effect of engine speed (i.e. turbulence) is very strong, the kernel expansion rate increasing with engine speed. Increasing the equivalence ratio also increases the propagation speed. The rate of flame growth measured in the engine is shown to go through a minimum for a burnt kernel radius of about 2 mm which varies with the equivalence ratio. The minima of the flame velocity at this radius depend on mixture strength and turbulence level. The simultaneous recording of the pressure trace shows a correlation between the early flame behavior and the overall combustion speed.