Atsuya Okamoto

Hollow-Cone Like Spray Formation by Using Plate Type Multi-Hole Nozzle

This paper describes multiple hollow-cone spray formation behavior by using newly developed plate-type multi-hole nozzle. The nozzle consists of multi-hole nozzle plate, flat tip needle, and thin screens located between the nozzle plate and the needle. One of the remarkable features of the nozzle is better atomization with relatively low fuel pressure. Flow pattern was observed in detail and the atomization characteristics were examined experimentally. It was found that hollow-cone shaped liquid film was injected from each nozzle hole. The shape of each liquid film was similar to that from swirl atomizer. Breakup length of the liquid film was much shorter than that from conventional plate-type nozzle. Mean droplet size was also much smaller than that of the conventional nozzle. Liquid flow in the nozzles was simulated numerically and the mechanism of hollow-cone liquid film formation was discussed. The results showed that the liquid flew into each nozzle hole with circumvolution. Owing to the circumvolution, hollow-cone liquid film was injected from each nozzle hole.

Spatial Distribution of Droplet Diameter of Wall-impinging-spray for Direct Injection Gasoline Engines

Spray characteristics such as spray shape and spatial distribution of droplet diameter remarkably influences on output and exhaust emissions of direct injection gasoline engines. Especially, spatial distribution of the droplet diameter after impingement of a spray against a piston cavity is one of the most important factors for output and exhaust emissions, but is not revealed sufficiently because of the difficulties of measurement. In this paper, a new laser holography method that can obtain spatial distribution of droplet diameter over the spray in a short time was developed. And with this method, differences of spatial distribution of Sayter mean diameter (SMD) of droplets between before and after impingement on a flat wall in a high-pressure chamber were revealed using a prototype injector. Effects of impinging angle and distance against the wall on spatial SMD distribution were also investigated.

Development of a Technique for Measuring the Internal Flow of Fuel Nozzles by Using Fluorescence PIV

A new quantitative technique for measuring the internal flow of fuel injection nozzles was developed. This technique is characterized by the use of transparent models enlarged seven times, and application of the refractive index matching method using Turpentine-Tetraline mixing oil and the fluorescence PIV that can eliminate the light scattered from gas-liquid border surface. This technique enables the measurement of velocity flow field in the sac chamber and nozzle holes. And, we report one analyzing result applied the multi-hole nozzle by using this method.