Quasi dimensional numerical investigation of syngas fuelled engine operation: MBT operation and parametric sensitivity analysis

The formulation, validation and application of a thermodynamic quasi dimensional SI engine simulation model for syngas fuelled operation is reported. The QD approach establishes the dependence of turbulent combustion on mixture thermo-physical properties and fluid domain average turbulent parameters, eliminating the need for domain discretization (unlike in multi-dimensional models). Turbulent combustion is formulated along the Eddy Entrainment Laminar Burn-up concept (Williams-Klimov criterion) with non-linear dependence of mixture burn rate on local laminar flame speed and turbulent intensity. Simulations are reported for syngas fuelled operation of a six cylinder engine and compared with experimental pressure and heat release traces. Maximum brake torque stoichiometric operation pressure and heat release simulation traces evolve closely with corresponding experimental traces. The simulation peak pressure and IMEP deviations remain within 5% and 2% of experimental traces respectively while the position of peak pressure overlaps within ±0.5 deg. Parametric sensitivity analysis for load, mixture quality and ignition timing are also addressed. Overall, the simulation results are in accordance within 5% of experimental results as long as the parametric variations are within the regimes of tuning of empirical correlations. In general, the versatility and robustness of quasi dimensional approach to simulate non-regular bio-derived alternative fuels is established.