ICLASS 97
Proceedings of the Seventh International Conference on Liquid Atomization and Spray Systems

ISBN Print: 89-950039-2-8

Characteristics of the Internal Flow in a Diesel Injection Nozzle

DOI: 10.1615/ICLASS-97.210
pages 175-182

Résumé

The effects of the internal flow in a D. I. diesel injection nozzle on the atomization of a spray were analyzed experimentally and numerically. Flow visualization studies were made using a transparent acrylic model nozzle. Water instead of diesel fuel was used as the injection liquid. The nozzle geometry was scaled up ten times and the injection pressures for the model nozzle were carefully scaled up so as to achieve a Reynolds number at the discharge hole the same as the diesel nozzle. A polystyrene tracer, a stroboscope, and a still camera were used to visualize the flow pattern in the region of the sac chamber and the discharge hole. The simulation results showed approximately good agreement with the experimental results. When the needle lift was small, the high turbulence in the sac chamber generated by the high velocity of the needle seat flow makes the spread angle of the spray plume large. By locating the discharge hole on the upper side of the sac chamber, the turbulence intensity in the sac chamber increases and the spread angle of the spray plume becomes large. Cavitation, which arose from the sac chamber, makes the spread angle of the spray large but the discharge coefficient small.