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In order to clarify the trend of PM emission characteristic caused by fuel change, we propose a fundamental flame research method using a small pool flame system. Characteristics such as size distribution and formation rate of PM from laminar diffusion flames of gasoline fuels (JIS No.1 and No.2) were investigated by an electric microbalance and a SMPS (Scanning Mobility Particle Sizer). PM exhaust from flame of surrogate gasoline fuels and hydrocarbon fuels of various chemical structures were also measured. As the result, it was found that both of exhaust-PM concentration and PM number peak size increased with increasing of alkene and aromatic compositions in fuel.

This paper presents the experimental analysis for the turbulence in the combustion chamber of a direct injection (D.I.) diesel engine. A dual beam mode, forward-scattering laser doppler velocimeter was applied to the flow measurement in a four-stroke, single-cylinder direct injection diesel engine of 110 mm bore and 125 mm stroke. The turbulence component was separated from instantaneous velocity using a high-pass filter. As a result, the difference in turbulent intensity between the intake and compression processes was discussed. Also, the effect of intake port and piston cavity shapes, the compression ratio and the engine speed on the turbulent intensity were clarified. In addition, the empirical equation for the decay of turbulent intensity in the compression process was expressed by a function of the Reynolds number based on the mean swirling flow.

Multi-stage injection diesel spray was investigated to understand the internal flow of a diesel spray. This multi-stage spray consisted of two sprays (we called them the first and second sprays) which were formed by a split injection with a short dwell time. In this paper, we discussed the dynamic behavior of a two-stage injection diesel spray. Especially, we focused on the characteristics of internal velocity and the decay of spray density fluctuation. When the injection rate of a conventional spray increased within an injection period, a spray tip of initially injected fuel was caught up and overtaken by the spray of a following injection. Then the internal structure of a conventional spray greatly depended on the internal spray velocity controlled by the injection rate. Since the second spray penetrated into the first spray, the spray tip motion of the second spray could be considered to be similar to the behavior of an internal spray motion in a conventional spray.

The behavior of diesel spray impinging on an inclined wall was experimentally investigated in a pressurized vessel. To clarify the wall effect on a diesel spray, a relative angle of the inclined wall to a spray axis was varied. Spray penetration along the wall was observed optically and it was compared with that of a free spray. To evaluate various spray motion quantitatively, a spray path penetration which described a development of a spray tip along the wall was newly introduced. To observe an internal structure of the spray, it was visualized by a YAG laser sheet light and its tomographic image was captured on a film. The photo-image on a film was taken into an image analyzing computer using a high resolved image scanner. A high density zone in the tomographic image was extracted to clarify the internal structure of an impinging spray. The main parameter of the relative position of the wall was its inclined angle which was defined as the angle between the spray axis and wall.