A Combustion Model with Reduced Kinetic Schemes for S.I. Engines Fuelled with Compressed Natural Gas 2005-01-1123
The paper describes the development of a reduced kinetic scheme for the evaluation of the main chemical species (particularly NO and CO) in premixed turbulent flame and its application to a quasi-dimensional combustion model for spark ignition engines.
The proposed mechanism is based on the kinetic solution of three transport equations for NO, CO and H, coupled with the partial equilibrium of the so-called water-shuffle equations to derive the OH, O and H2 concentrations. The remaining species are computed applying the element conservation, while the required prompt levels were determined by a separate chemical 1D code for laminar combustion.
The proposed chemical scheme was locally validated, considering a turbulent flame inside a premixed flow of air and methane, ignited by a parallel flow of hot gases, by means of a CFD simulation. Successively, it was embedded into a quasi-D thermodynamic combustion model developed by the authors for the simulation of S.I. and C.I. engines. The enhanced model has then been adopted to simulate the behavior of a production S.I. engine purposely modified to run on compressed natural gas (CNG)