Analysis of thermodiffusive instabilities and flame front wrinkling in a hydrogen-fueled engine

This study investigates the interplay between thermodiffusive instabilities (TDI) and flame front wrinkling in a hydrogen-fueled internal combustion engine (ICE). High-speed planar laser-induced fluorescence (LIF) of the SO₂ tracer was employed to visualize flames in an optically accessible, spark-ignited ICE operating under a lean H₂ mixture at 400 rpm and 800 rpm. The results reveal that TDI cells are distinctly more pronounced at 400 rpm and in slower flames, while at 800 rpm, increased turbulence suppresses cell development and enhances overall flame wrinkling. A negative correlation between these two features indicates that TDI cells flourish in less disturbed conditions, whereas turbulence-driven wrinkling disrupts their formation. These findings suggest that at higher, more realistic engine speeds, TDI cell formation is significantly mitigated. However, other instability-driven effects, such as localized heat release variations, wall heat transfer, and flame quenching, may still play a crucial role in H₂ engine combustion. Understanding these interactions is essential for accurately modeling and optimizing hydrogen-fueled ICEs.