Multi-dimensional Modeling of Flame Kernel Growth and Flame Propagation Processes in Spark-Ignition Engines English Free Members only

  • Category Technical paper
  • Edition SIA
  • Date 12/04/2013
  • Author T. Lucchini, G. D'Errico, A. Onorati, G. Montenegro - Politecnico di Milano
  • Language English
  • Type PDF file (683.85 Ko)
    (Downloadable immediately on receipt of online payment)
  • Number of pages 10
  • Code R-2013-06-20
  • Fee Free

In this work, the authors intend to present a comprehensive, multi-dimensional model that can be used to predict the initial combustion stages in SI engines. In particular, the spark channel is represented by a set of Lagrangian particles where each one of them acts as a single flame kernel. Each particle is convected by the gas flow and its growth is governed by flame speed and thermal expansion due to the energy transfer from the electrical circuit. From particle positions and size it is then possible to reconstruct the flame surface density distribution, that is then used by the gas phase to compute the fuel reaction rate. A simplified model for the secondary electrical circuit was applied to estimate the amount of energy transferred as function of the circuit properties (equivalent resistance and inductance), discharge energy and time. All the effects of the flame kernel growth are grouped into a single source term, that is added to the flame surface density transport equation, solved following the Extended Coherent Flamelet Model (ECFM) The proposed model has been extensively validated with experimental data available in the literature accounting for the effects of different engine speeds, air/fuel ratio, ignition systems and spark-plug position. Validation was performed by comparing computed and experimental evolution of the burned gas volume. Encouraging results were achieved for a wide range of operating conditions.