Generation of monodisperse aerosols by combining aerodynamic flow-focusing and mechanical perturbation

Abstract

A novel instrument has been developed for generating highly monodisperse aerosol particles with a geometrical standard deviation of 1.05 or less.This aerosol generator applies a periodic mechanical excitation to a micro-liquid jet obtained by aerodynamic flow-focusing.The jet diameter and its fastest growth wavelength have been optimized as a function of the flow-focusing pressure drop and the liquid flow rate.The monodisperse aerosol generated by this instrument is also charge neutralized with bipolar ions produced by a non-radioactive, corona discharge device.Monodisperse droplet generation in the 15-to 72-mm diameter range from a single 100-micron nozzle has been demonstrated.Both liquid and solid monodisperse particles can be generated from 0.7-to 15-mm diameter by varying solution concentration, liquid flow rate, and excitation frequency.The calculated monodisperse particle diameter agrees well with independent measurements.The operation of this new monodisperse aerosol generator is stable and reliable without nozzle clogging, typical of other aerosol generators at the lower end of the operating particle size ranges.