The conditions to produce liquid droplets of uniform size were investigated experimentally. The number of droplets produced and the region which allowed production of uniform-size droplets were related with the operating conditions, design parameters of nozzle and physical properties of liquid.
It was confirmed that the number of liquid droplets produced is equal to the vibration frequency within the uniform region, and the diameter of a liquid droplet which is equivalent to a sphere was calculated by Dabora''s equation.
The region producing uniform droplets was not affected by the appropriate amplitude of nozzle vibration, but was affected by nozzle diameter, physical properties of liquid and frequency. Nondimensional empirical equations for their prediction were obtained.
It was found that the range of liquid velocity of the uniform region corresponds to the range of the forced oscillating smooth jet from a vibrating nozzle. Uniform droplets were produced from the forced oscillating smooth jet which is vibrated at an appropriate amplitude and frequency.