Determination of the Modes and the Conditions of Ultrasonic Spraying Providing Specified Productivity and Dispersed Characteristics of the Aerosol

Abstract

For the spraying of liquids and the coating process at high-tech productions the method of ultrasonic spraying in a layer having a number of advantages such as low energy capacity, high productivity, fine-dispersity of obtained aerosol and the absence of spraying agent, is used. However the main problem of ultrasonic spraying application is the absence of the reliable dependences of spraying characteristics (drop diameter and spraying productivity) on the liquid properties (viscosity, surface tension), modes (frequency and vibration amplitude of spraying surface) and conditions (the thickness of liquid layer) of the ultrasonic action. In order to determine these dependences it is proposed the model based on cavitation and wave theory of the drop formation, which allows obtain for the first time theoretical ground of the existence of optimum thickness layer, at which free surface of liquid is acted upon by maximum energy providing drop detachment. The model analysis lets show advisability of the application of vibration frequency of more than 100 kHz for the drop generation with the size of 10 μm and less with the productivity of no less than 0.2 ml/s. Obtained results are proved by the experimental studies, which allow their use for the formulation of the technical requirements to the ultrasonic sprayers at the realization of different technological processes.

Keywords

• Ultrasound; Spraying; Viscosity; Aerosol; Thickness of the layer; Capillary wave.