Experimental Study of the Effect of High Back-Pressure on the Atomization of a Plain Jet Injector Under Coaxial Air Flow

Abstract

An experimental study was carried out on the effect of high back-pressure on the spray characteristics of a plain jet injector in coaxial air flow. The back-pressures tested ranged from 100 to 1600 kPa, the velocity range of coaxially flowing air is 60–120 m/s. The working fluid was water. The injector hole diameter was 0.5 mm. The key feature of the experiment was to use a convergent-divergent nozzle connected to the atomization test chamber to maintain a high back-pressure in the chamber for atomization, and at the same time, to maintain a high-velocity air flow in the atomization region. Thus, it totally eliminated the air recirculation and droplet slow-settling problem in the commonly used pressurized vessel for high back-pressure atomization study. The results show that the Sauter mean diameter decreases monotonically with the increase of back pressure. At different air velocities, the effect of back pressure is different. The drop size distribution becomes more non-uniform slightly with increasing back pressure.