Computation of Premixed-Charge Combustion in Pancake and Pent-Roof Engines

Multidimensional computations were made of spark-ignited premixed-charge combustion in a pancake-combustion-chamber engine with a centrally located spark plug and in two pent-roof-chamber engines, one with a central spark plug and the other with dual lateral spark plugs. A global combustion submodel was used that accounts for laminar kinetics and turbulent mixing effects. The predictions are compared with available measurements in the pancake-chamber engine over a range of loads, speeds, and equivalence ratios. A sensitivity study was performed to understand the sources of discrepancies between the predictions and measurements. It was found that the discrepancies could be explained through uncertainties in the gas temperature, turbulence intensity and length scale existing in the chamber prior to combustion.