Effects of mixture heterogeneity on flame propagation in a constant volume combustion chamber

摘要

Although mixture formation is considered important in actual spark-ignition engines, a full understanding of the combustion characteristics of a heterogeneous mixture has not yet been achieved. In this study, in order to clarify the effects of a heterogeneous concentration distribution of the fuel-air mixture on the flame propagation process, different degrees of heterogeneously distributed mixtures were created by the motion of a pair of perforated plates in a constant volume combustion chamber. The laser Rayleigh scattering method was applied for quantitative visualizations of these mixture distributions. To control the distribution of the mixture concentration and the turbulence intensity independently, the flow in the chamber and its turbulence intensity were also measured by a laser sheet method and the LDV technique. By isolating the effects of the mixture distribution on the flame behavior from those of the turbulence, the flame structures and development properties at different levels of heterogeneous mixture distribution were investigated in detail.