Yasuhide Tani

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.

Visualization of the evaporating process of fuel spray in the cylinder of a diesel engine.

A single cylinder engine with the combustion chamber mounted on the piston was designed to allow visualization in the direction of the cylinder axis. By using this engine, the evaporating process of the fuel injected into the combustion chamber was observed. High speed Schlieren, shadowgraph, and back-illuminated movies were taken for detailed observation of the combustion chambers with a single hole injector and a swirl injector which have different injection characteristics. The one with a single hole injector shows strong collision of the spray with the bottom of the chamber and fast evaporation. Another with a swirl injector shows no trace of such collision and relatively slow evaporation.