PHYSICAL AND MATHEMATICAL MODEL OF THE MECHANISM OF ULTRASONIC DEHYDRATION OF MATERIALS WITHOUT PHASE TRANSITION OF LIQUID INTO VAPOR

The paper theoretically investigates the possibility of ultrasonic oscillations to remove moisture from capillary-porous materials by dispersing it under the action of shock waves formed during cavitation phenomena in the liquid phase. A physical and mathematical model based on analysis of slow growth of cavitation bubble of distorted cylindrical shape taking into account influence of cylindrical capillary walls limiting its oscillations was developed and presented. The optimum range (150-170 dB) of sound pressure levels (at the oscillation frequency of 22 kHz) at which dispersion of moisture is realized, was found. It was found that the optimal conditions of exposure to ultrasonic oscillations (according to the geometry of the sample) on the dried material are realized when the size or thickness of the layer of the dried material corresponds to the length of the ultrasonic oscillations in the air.