The Effect of Swirl on Spark-Ignition Engine Combustion

Abstract

In order to investigate the effect of swirl on combustion in a spark-ignition engine, a new experimental apparatus, namely, the single-event engine was prepared. The swirl flow in the cylinder was visualized by a smoke-wire method, and a laser Doppler anemometer and a hot-wire anemometer were adopted for the velocity measurement. The turbulence intensity was determined on the basis of the hot-wire data. A stoichiometric propane-air mixture was ignited at the center of the combustion chamber ; thus, the flame was propagated almost axisymmetrically in the flow field at various swirl intensities with no squish flow. The burning velocity, S_T, and the thickness of burning zone, δ_T, were determined in the spark-ignition engine cylinder. The result show that S_T and δ_T increase with increasing the turbulence intensity, and that δ_T is correlated linearly with S_T except under the condition of weak turbulence.