Spray-Wall Dynamics of High-Pressure Impinging Combustion 2019-01-0067

The fuel spray impingement on the piston head and/or chamber often occurs in compact IC engines. The impingement plays one of the key roles in combustion because it affects the air-fuel mixing process. In this study, the impinged combustion has been experimentally investigated to understand the mechanism and dynamics of flame-wall interaction. The experiments were performed in a constant volume combustion chamber over a wide range of ambient conditions. The ambient temperature was varied from 800 K to 1000 K and ambient gas oxygen was varied from 15% to 21%. Diesel fuel was injected with an injection pressure of 150 MPa into ambient gas at a density of 22.8 kg/m³. The natural luminosity technique was applied in the experiments to explore the impinged combustion process. High-speed images were taken using a high-speed camera from two different views (bottom and side). An in-house Matlab program was used to post-process the images. The potential region of soot formation was found on the impinging plate based on the strength of local soot luminosity. The effect of air entrainment on the flame propagation was investigated by studying the curvature of the flame outer boundary when flame impingement. Further, the apparent heat release rate (aHRR) was measured during flame impingement and the governing combustion modes (premixed and diffusion) in the impinged combustion were discussed.