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The experiment-based droplet impinging breakup model was applied to a fan shaped spray and the impinging behavior was analyzed quantitatively. Evaluation of the quantitative results with validation tests verified the following. The model enables prediction of fan shaped spray thickness after impingement caused by the breakup of fuel droplets, which could not be represented with the Wall-Jet model, widely used at present. Fuel film movement on a wall is negligible when the injection pressure of the fan shaped spray is high and the spray travelling length is not too short. The proposed heat transfer coefficient between fuel film and the wall is too small to represent the vaporizing rate of the fuel film.

This paper confirms a structure for the soot formation process inside a burning diesel jet plume of oxygenated fuels. An explanation of how the soot formation process changes by the use of oxygenated fuel in comparison with that for using a conventional diesel fuel, and why oxygenated fuel drastically suppresses the soot formation has been derived from the chemical kinetic analysis. A detailed chemical kinetic mechanism, which is combined with various proposed chemical kinetic models including normal paraffinic hydrocarbon oxidation, oxygenated hydrocarbon oxidation, and poly-aromatic hydrocarbon (PAH) formation, was developed in present study. The calculated results are presented to elucidate the influence of fuel mixture composition and fuel structure, especially relating to oxygenated fuels, on PAH formation. The analysis also provides a new insight into the initial soot formation process in terms of the temperature range of PAH formation.

OH radical generated in a DI diesel engine has a close relationship to soot oxidation. To clarify this fact, the distribution of the natural emission of OH radical was captured by means of an interference filter system and that of soot was detected by the simultaneous application of a laser induced incandescence (LB) and a laser induced scattering (LIS). The experiments were carried out in a small sized high-speed DI diesel engine installed with an optical access view. The generation of OH radical and the formation/oxidation of soot are discussed by using both images.

The hydrodynamic details of droplet-droplet and droplet-liquid film interactions on solid surfaces are believed to have a significant role in spray impingement phenomena, yet details of this interaction have not been clearly identified. The interaction among the droplets during impact affects their residence time on the surface, spreading, and droplet and liquid film stability. After impact, droplet interactions affect droplet collisions, coalescence and liquid splashing, This interaction affects secondary atomization and the droplet dispersion characteristics of the impingement process. In this study, details of droplet-droplet and droplet-liquid film interactions in solid surface impingement have been visualized using high speed photography. The effects of these interactions on secondary atomization and droplet dispersion have been quantified.

This paper presents the analysis of atomization and vaporization processes in a flash boiling spray based on experimental results obtained from injection systems in the suction manifold of a gasoline engine. Two kinds of liquid fuel, n-Pentane and n-Hexane, were injected into quiescent atmosphere at room-temperature and low-pressure through a pintle type injector with electronic control. The spray characteristics of both fuels below various atmospheric pressures were investigated in detail by taking photography. Then, in the region of flash boiling, where the back pressure was below the saturated vapor pressure of fuel, the bubble nucleation process due to the flash boiling was modelled by both the measurement results of bubble and the nucleation rate equation using the degree of superheat of the liquid fuel.

There is a concept that the increase in the temperature of charge in a combustion chamber and the shield of heat transferred through a chamber wall can facilitate the oxidation of soot and reduce the discharge of soot from the engine. In the experiments presented here in, an IDI diesel engine was used to inspect the concept. The engine was installed a bigger sized cylindrical swirl chamber which was equipped with two flat quarts windows, in order to observe the combustion phenomena and to apply the optical measurement. The experiments were carried out using two types of divided chambers, that is, the swirl chamber made of ceramics and that made of steel, to examine the the effects mentioned above.

In a high-speed DI diesel engine, fuel sprays impinge surely on a wall of a piston cavity. Then the phenomenon of the heat transfer between the impinged spray and the wall appears and it has the strong effect on the combustion processes of the engine. The purpose of this study are to clarify basically the heat transfer characteristics. In the experiments, the fuel was injected into the quiescent inert atmosphere with a high temperature under high pressure field, and an evaporative single diesel spray was impinging upon a flat wall. And, the temperature distribution on the wall surface in a radial direction was detected by the Loex-Constantan thin film thermo-couples. Thus, the heat flux between the impinged spray and the wall surface was calculated from the temperature profile within the wall by Fourier's equation using the finite difference method, under the assumption of the one-dimensional heat conduction.