The Nature of Turbulent Flame Propagation in a Homogeneous Spark-Ignited Engine

This work relates flame speed to turbulence in a homogeneous-charge spark-ignited engine. A quartz-piston engine, using both shrouded and non shrouded valves with four spark locations, was operated over a range of engine speed and spark timing in order to generate large variations in flame frontal area, turbulence, and pressure. Burning velocities were determined from pressure-time data using a diagnostic spherical-flame model and are compared to hot-wire turbulence measurements. The resulting correlation for burning velocities throughout the engine cycle is compared to existing flame theories, published turbulent flame data, and proposed turbulent flame models for S. I. engines.