2015 年 15 巻 2 号 p. 124-131
Aiming to develop simple strategies for the uniform droplet production, experimental investigations were made on the breakup of laminar liquid-jet injected downward into the atmosphere from a cylindrical nozzle which was oscillated sinusoidally. The breakup manner, the breakup time and the size distribution of generated droplets were examined for the cases of vertical, lateral and oblique oscillations. The inner diameter of nozzle was 0.9mm. The liquid-injection velocity was ranging mainly from 0.5 to 1.5m/s - the laminar jet regime, the frequency range of oscillation was 100-800Hz, and the amplitude range was 0.5-5μm. Detailed investigations were performed employing ethanol as test liquid, first. When the nozzle was oscillated obliquely, the liquid jet broke up rapidly in synchronization with the oscillation within the frequency range from the axisymmetric Rayleigh mode to the twice. The outstanding satellite droplets were seldom found and the size distribution of generated droplets was almost close to a mono- dispersed state, although the amplitude of oscillation was invisibly small. Experimental investigations were also performed employing water and 60wt% aqua-solution of propylene-glycol. Finally, it was found that the oblique oscillation of liquid-injection nozzle was suitable for the periodic breakup and the uniform droplet generation.
