The Development and Analysis of a Multistage Spraying Method for Liquids in an Ultrasonic Field

Spraying various liquids (primarily aqueous solutions of various substances) is widely used in various technological processes. For most of them, high dispersibility and a narrow droplet size distribution are essential. Ultrasonic spraying allows these parameters to be achieved. However, the higher the dispersity of droplets produced by ultrasonic spraying, the lower the spray productivity. To solve this problem, we propose a method of multistage spraying, consisting of the generation of a large number of particles of large initial size (to ensure high productivity) and their subsequent destruction by propagation in a periodic ultrasonic field (to ensure small droplet sizes at high productivity). To experimentally determine the capabilities of this technique, a tubular emitter in the shape of a cylinder with a stepped-variable cross-section was designed. The configuration of the ultrasonic field inside the emitter (22.2 kHz; 182 dB) implements three-stage spraying (the number of sputtering stages corresponds to the number of anti-nodes along the emitter axis). The effectiveness of the proposed and developed technique, suitable for the generation of droplets smaller than 40 µm, with performance exceeding the known ultrasonic spray techniques by at least 10-fold, was confirmed in the course of the conducted research.