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This paper presents the adjustment of an extended coherent flame model - three zones (ECFM-3Z) by the analysis of its variables α and β for application in a 3D computational fluid dynamics (CFD) model of a two valve engine fueled with ethanol. The engine is aspirated and uses direct injection of ethanol as a single injection. High frequency pressure gauges are used at the cylinder, intake and exhaust manifolds in order to perform a three pressure analysis (TPA) and this data were used as boundary conditions for the CFD model. In the tests the engine speed varied in the range of 1500 to 4000 rpm, and throttle position in the range of 20% to 100% (WOT), although wide open throttle (WOT) was used for adjustment of the combustion model parameters. The computational model uses the ES-ICE module of PROSTAR for moving mesh generation, implementation of boundary conditions and transient analysis of global variables.

One-dimensional models for internal combustion engines analysis are very useful to simulate its systems through a relatively low computational effort. Based on this idea, this paper presents the simulation of a spark-ignition engine using one-dimensional models implemented in object oriented programming by the authors. The model was adapted to simulate a research four valves, single cylinder, spark ignition, reciprocating internal combustion engine. The gas in the cylinder was described by conservation equations, including the momentum conservation equation, that wasn’t found in the checked literature. For the combustion, a two zones model was implemented, based on combustion wave equations, such that detonation and deflagration are calculated by the same set of equations. The flame propagation geometry was considered to be spherical.

The internal combustion engine flow field has direct influence on the engine performance regarding both power and emissions. The intensity, location and direction of the flow structures known as tumble, cross tumble and swirl are key parameters on design and development of combustion chamber, especially on the spark plug position. This paper presents a Computational Fluid Dynamics (CFD) analysis on the flow field structures inside a two valve engine through the late compression stroke using commercial three dimensional software. The magnitude of the velocity vector has been plotted as a scalar in a contour map, so the center of the vortex is represented by the zero velocity region. Special attention is given to the spark timing, for it's the most important instant for determining the center of the swirl vortex. This is because the zero velocity region is considered the best place for the spark plug position, from the fluid dynamic point of view.