Auto-ignition phenomena with relevance to lean premixed prevaporised (LPP) combustion have been investigated with laser-optical methods. A generic mixing reactor with optical access was set up, offering the possibility to observe the reaction within a droplet laden hot air flow (up to 1100 K) at elevated pressure levels (0.8 MPa). The measurements aim at a detailed understanding of the local conditions under which auto-ignition and combustion occur in the mixing duct. The onset of chemical reactions in the fuel-air mixture was imaged by planar laser-induced fluorescence (LIF) of formaldehyde (CH2O). Formaldehyde is formed during reaction progress leading to auto-ignition and consecutively consumed during combustion. Simultaneous imaging of droplet Mie scattering was applied to study the correlation of their location with the ignition. Furthermore, the chemiluminescence signal of the flame was analysed, using a high-speed ICCD camera system, in order to track the propagation of the individual ignition spots. PLIF平面激光誘導(dǎo)熒光火焰燃燒檢測系統(tǒng)