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In internal combustion engine, it is necessary to grasp droplet evaporation for using liquid fuel efficiency and improving exhaust gas composition. However, it has not known completely yet. In this study, fuel droplet of approximately 20μm diameter that is assumed to be in combustion chamber is injected by experimental apparatus. After that, droplet goes to butane flame. We observed by high-speed camera, and experimentally considered the effects of heat flux on the fuel droplet evaporation and breakup phenomenon. For the sample fuel, we use kerosene and diesel oil. It is important for understanding evaporation condition to know temperature around droplet in butane flame. Thus, flame temperature is measured by sheathed thermocouple. Heat flux is changed by initial velocity. From experiment, we found some result. Time that from injector tube to location of breakup of the droplet is short by increasing heat flux.

Liquid fossil fuels such as gasoline, diesel oil, and kerosene are widely used as a fuel of various transportation apparatus and generating electricity apparatuses including the automobiles. The spray combustion has been widely used for internal combustion engine to use the fuel efficiently. But some parts of the phenomenon are not elucidated because this combustion method is complicated phenomenon. To elucidate this phenomenon, there are many ways of analyzing droplet. For example, observing a single droplet which suspended by a catenary or under the microgravity. However, those methods are not enough simulation of a real droplet in the internal combustion engine. In this study, we developed an apparatus which could inject a freedom droplet of diameter about 30µm. It is considered that the droplet is in a real internal combustion engine. And the apparatus was installed in a container which could realize elevated temperature and pressure.

In our study, phenomena is observed that 30µm droplet become breakup by UV laser irradiation. This phenomena change by composition of droplet. Then we focused on difference of absorbance, hexadecane and o-xylene are used as fuel. The former do not absorb UV enough and the latter do absorb UV enough. And authors examined the relation mixing ratio and breakup phenomena using blended fuel which consist of hexadecane and o-xylene. With regard to the UV laser we used, wavelength is 266nm, flash of time is 10nsec and laser intensity is 15mJ. CCD camera, strobe light with 180nsec flash time and lens of ten magnification were used for observation. As a result, we obtained the following; 1) A state of breakup phenomena depend on concentration of o-xylene. 2) The absorbance is not related with a state of breakup phenomena.