Experimental Study of Aerosol Coagulation during the Formation of Vortex Flows in a Heterogeneous Ultrasonic Field

A new approach to increasing the efficiency of coagulation of finely dispersed aerosols by forming vortex flows in a nonuniform ultrasonic field is proposed and experimentally investigated. It has been established that vortex flows formed by a flat transducer in a nonuniform ultrasonic field yield an increase in coagulation efficiency when acting on a gas-dispersed flow injected into the coagulation chamber at a rate of up to 0.2 m/s. When it is exceeded, the structure of the total velocity field is disrupted and aerosol particles fly through the chamber without having time to interact with the acoustic flow field in a time sufficient for settling on the walls. The coagulation efficiency due to vortex flows increases linearly with an increase in the sound pressure level to 165 dB. After this, no further increase in coagulation efficiency is observed. It was found that the efficiency of coagulation versus coagulation in a uniform ultrasonic field for droplets 0.2–0.6 μm in size increases by 25%; for droplets 1.8 μm in size, by 20%; and for droplets larger than 2.5 μm in size, no more than 17%.