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Ultrasonic agglomeration is a promising technology for the preprocessing of fine-dispersed particles (i.e., PM2.5), as it significantly improves the efficiency of traditional devices for the particles collecting in gases. However, the results of theoretical and experimental studies indicate that the agglomeration process is too slow, especially for PM2.5 and small concentrations of particles. This study proposes an approach to improving particle agglomeration efficiency and provides a mathematical model. This model considers the moving of particles by vortex acoustic (Eckart) flows arising in a standing wave in addition to the main known mechanisms of acoustic particle interaction (such as orthokinetic and hydrodynamic interaction). The results of the calculations showed an increase in the efficiency of ultrasonic agglomeration of submicron particles (more than 4 times) due to the formation of Eckart flows in the resonant gaps. The highest increase in efficiency is achieved at small particle counting concentrations (e.g., the agglomeration time is reduced by more than 4 times at a counting concentration of 0.25 × 10¹⁰ m^-3 and the sound pressure level without a reflector of 150 dB). At higher concentrations (from 0.25 × 10¹⁰ to 1 × 10¹⁰ m^-3) the agglomeration time is reduced by at least 1.5 times (in the range of sound pressure levels of 150-155 dB). The obtained results can be practically implemented in the designs of gas cleaning systems using Eckart flows with ultrasonic exposure on the resonant air gap.

The article presents the results of research aimed at increase of the efficiency of gas cleaning equipment based on the Venturi tube using high-intensity ultrasound. The model based on known laws of hydrodynamics of multiphase mediums of dust-extraction in Venturi scrubbers was proposed. Modification of this model taking into account ultrasonic field allows evaluating optimum modes (sound pressure level) and conditions (direction of ultrasonic field, square and number of ultrasonic sources) of ultrasonic influence. It is evaluated that optimum for efficient gas cleaning is the mode of ultrasonic action at the frequency of 22 kHz with sound pressure level of 145. . . 155 dB at the installation of two radiators with area of 0.14 m 2 , four radiators with area of 0.11 m 2 or six radiators with area of 0.08 m 2 at the angle of 45 degrees to the axis of Venturi tube. Numerical calculations showed that realization of ultrasonic action is the most efficient for the reduction (up to 15 times) of the content of fine-dispersed fraction (2 µm and less), which is impossible to extract without ultrasonic action. The received theoretical results were confirmed by industrial testing by typical dust-extraction plant and used as foundations of development of apparatuses with the radiators of various sizes.

The article describes the design of an ultrasonic emitter for exposure to gas-dispersed media. A longitudinally oscillating cylindrical body of half-wave length, connected to a piezoelectric transducer, serves as the basis for the design of an ultrasonic emitter. The optimization of the geometric dimensions of the radiator made it possible to ensure the uniformity of the distribution of the vibration amplitudes of the radiating end surfaces. The execution of the connecting plane for excitation of vibrations, deepened relative to the end radiating surface, made it possible to increase the amplitude of vibrations by 2 times. Optimization of the design using the finite method made it possible to create a longitudinally oscillating ultrasonic emitter capable of providing exposure to gaseous media with an intensity of at least 145 dB at a power consumption of no more than 90 W.

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