Formation and evaporation of fuel films on various surface roughness walls were investigated. Liquid fuel of iso-octane was injected from multi-hole injector of a DISI engine. Injected spray was impinged on an aluminium wall having low or high roughness (Ra = 1.07 µm to 17.1 µm) and fuel film was formed on the wall. Wall surface temperature before fuel spray impingement was controlled by an electric heater (25°C to 130°C). Fuel film behaviour with elapsed time under various wall conditions was captured by a high-speed camera. Fuel film spreading area change and evaporation lifetime of the fuel film were obtained from the captured top view image. As a result, it was found that the fuel film spreading area became narrower with an increase of the surface roughness. The evaporation lifetime of fuel film became shorter with an increase of the surface roughness.

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