Characterization of flame front wrinkling in a highly pressure-charged spark ignition engine

Abstract

Particle Image Velocimetry (PIV) technique has been employed to investigate turbulent flame propagation in a relatively quiescent, optically accessed, boosted, two-stroke spark ignition engine. Turbulence scales and flame structure have been characterized based on Fourier analysis of an independent stationary coordinate at elevated pressures. Analysis shows that turbulence, with an initial rms value of u', is modified by flames, and the strong induced velocity field ahead of it. As the flame grows, the persistence of larger scale structures as well as smaller scale wrinkling is apparent. Power spectral density (PSD) of flame wrinkling exhibit the same general trend under different operating conditions. These are in a good agreement with the previous data measured from other rigs (i.e. burners and bombs), which featured lower pressures. These functions have been normalized by terms of wrinkling parameters and other turbulence parameters. General PSD functions are developed. These can predict the flame wrinkling behavior at low and high pressures, in different experimental apparatuses.