Increasing unsaturated dissolved oxygen concentration in water by fine bubbles induced by ultrasonic vibrations

Abstract

In the past, much research has centered on dispersing liquids into gases, and dispersing solids and liquids into liquids. However, there has been almost no research on dissolving gases into liquids by dispersion, possibly because of concerns about the effect of deaeration due to cavitation of a liquid by ultrasound. Here, we consider a method using ultrasound to finely disperse and dissolve a supplied gas. The method entails placing the gas supply outlet close to the tip of an ultrasonic longitudinal vibration source and dissolving the gas into the liquid by finely dispersing the gas by means of the vibrations. In this method, the occurrence of cavitation is reduced as much as possible and deaeration effects are reduced. Here, air is used as the gas to be dissolved and water is used as the solvent. The unsaturated dissolved oxygen concentration in water is used as an indicator for evaluating the proportion of dissolved air. The results show that ultrasonic vibration increases the concentration of oxygen dissolved in the liquid and that almost no deaeration by cavitation occurs.

Compact aerial ultrasonic source integrating the transverse vibration part with the bolt-clamped Langevin transducer

“…A uniform rod ultrasonic source is an aerial ultrasonic source that uses a bolt-clamped Langevin transducer (BLT), [25][26][27][28][29] is cylindrical with approximately the same diameter as the transducer, and is a simple directional source that emits sound waves perpendicular to the vibration surface. However, it is difficult for this type of source to produce high sound pressure because the amplitude of the vibration surface cannot be increased owing to the piston vibration (longitudinal vibration) of the entire uniform rod.…”

High-intensity aerial ultrasonic source with sharp directivity containing a compact circular vibrating plate

“…A typical existing aerial ultrasonic source that can easily emit powerful sound waves is the uniform rod-type source using a bolt-clamped Langevin-type transducer. [14][15][16][17][18] A uniform rod-type source is a simple directional source that can emit sound waves perpendicular to the vibration surface. However, it is difficult to produce high sound pressure because the amplitude of the vibrating surface cannot be increased owing to the piston vibration of the entire uniform rod.…”

Ultrasound source using a rectangular vibrating plate combined with rigid walls

“…Ultrasound is used in various fields. [1][2][3][4][5][6][7][8][9][10][11][12][13] In particular, ultrasound is used for deodorization, atomization, and aerosol aggregation. [14][15][16][17][18][19][20][21][22] These applications require intense ultrasound waves.…”

“…(1) We determined the design method for this vibrating plate and examined its vibration mode. (2) We determined the configuration of the rigid walls and the parallel reflective plate. (3) We analyzed the sound pressure distribution in the standing wave field formed by the sound source.…”