Comparison between LIF Measurements and Modeling Predictions of OH-HCHO During HCCI Mode Combustion Development

The present study investigates formaldehyde (HCHO) and hydroxyl radical (OH) Laser-Induced Fluorescence (LIF) in an optical HCCI (Homogeneous Charge Compression Ignition) engine fuelled with pure n-heptane and a mixture of Primary-Reference-Fuels (PRF25) at a fixed equivalence ratio (0.3) from a simulated EGR (Exhaust Gas Recirculation) rate of 10% and 50%. OH and HCHO fluorescence images are superimposed to the Heat Release Rate (HRR). The results show that these two species are complementary markers of the HCCI combustion process. A zero-dimensional single zone model with a detailed kinetic scheme is also developed and combustion simulations are compared to the HRR, OH and HCHO experimental data. A good agreement is obtained.