Masayuki TAMURA,¹ Teruhiro SAKURAI² and Hideo TAI¹

¹Fundamental Technology Laboratory, ²Energy & Environmental Technology Laboratory, Corporate R&D Department, Tokyo Gas Co., Ltd., 1-16-25, Shibaura, Minato-ku, Tokyo, 105-0023 Japan

(Received August 18, 1999; Accepted November 29, 1999)

A simultaneous visualization technique of reacting and unburned zones using laser-induced fluorescence (LIF) was applied to a high-pressure combustion field in an engine cylinder. Crevice flow from a crevice between a piston and a cylinder wall of a spark ignition gas engine was visualized by LIF of OH and acetone. OH was excited simultaneously with acetone that was seeded into fuel as a tracer by an excitation light at 283.92 nm. Fluorescence signals from each species were detected individually by two intensified CCD cameras using optical band-pass filters which transmit fluorescence wavelength of OH and acetone, respectively. Pressure- and temperature-dependence of LIF signals from each species were evaluated. From the visualized images, it was clarified that oxidation of the crevice flow is stopped at the time of exhaust valve opening. Effects of exhaust port pressure on the oxidation process were investigated.

Key words : laser-induced fluorescence, visualization, combustion, engine mass fractal, surface fractal, combined fractal, self-similarity, power law, fractal dimension

m-tamura@tokyo-gas.co.jp