Cycle-to-Cycle Fluctuation of Lean Mixture Combustion in Spark-Ignition Engineers

The cycle-to-cycle fluctuation of combustion in spark-ignition engines operated with a homogeneous lean-mixture of propane and air was investigated. The main results are as follows : (l) The configuration and size of flames in the early stage of combustion fluctuate remarkably from cycle to cycle, even if the mixture composition is kept constant. (2) A reduction of combustion period suppresses the cycle-to-cycle fluctuation of combustion. (3) The influence of the combustion fluctuation in the early stage on the whole combustion fluctuation varies with the length of the main combustion period.