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The article is devoted to the study of ultrasonic agglomeration of PM 2.5 in homogeneous and inhomogeneous ultrasonic fields. The possibility of increasing the efficiency of ultrasonic agglomeration by initiating acoustic streams in a resonant inhomogeneous ultrasonic field is shown. A inhomogeneous ultrasonic field with zones of high and low sound pressure levels formed using a bending-oscillating disk transmitter made it possible to initiate acoustic vortex-type streaming that promotes the movement of particles into the nodal areas of a standing wave and between them. Due to the formation of a inhomogeneous ultrasonic field, the efficiency of particle collection is increased: for PM 2.5, the efficiency reaches 95%; PM 1.5—92%; PM 0.5—85%. The results were obtained under the following conditions: concentration 2 × 10−2 g/m3, sound pressure level 165 dB, flow rate 6.2 m3/h. For comparison, when a homogeneous ultrasonic field is formed in the agglomeration chamber (under similar conditions), the efficiency of particle capture by inertial gas cleaning equipment does not exceed the following: for PM 2.5—89%; PM 1.5—85%; and PM 0.5—76%. The obtained research results made it possible to propose a design for an agglomeration chamber that can greatly increase the productivity of ultrasonic flow processing. [ABSTRACT FROM AUTHOR]

• Agglomeration efficiency is increased by generating toroidal acoustic vortex streaming. • Toroidal vortex streaming are generated using a flexural-oscillating disk radiator. • Acoustic streaming retain their structure at gas-disperse flow velocity up to 0.2 m/s. • The coagulation efficiency for submicron droplets increases up to 25 % In this paper a new approach to increase the agglomeration efficiency of finely dispersed aerosols by generating toroidal vortex streams in inhomogeneous ultrasonic field is proposed and studied. From the obtained experimental results (for two types of emitters) it could be established that the toroidal vortex streams generated in an inhomogeneous ultrasonic field provide an increase of the agglomeration efficiency when exposed to a gas-dispersed flow injected into the agglomeration chamber at a speed of up to 0.2 m/s. Further increase of the injected flow velocity leads to disruption of the structure of the generated vortex streams and agglomeration efficiency decreases. In the course of the analysis, it was found that the efficiency of agglomeration by toroidal vortex streams increases in direct proportion to the increase of the sound pressure level up to 165 dB. After that, no further increase in agglomeration efficiency is observed. By analyzing the agglomeration efficiency depending on particle size, it was possible to verify that the efficiency of agglomeration in comparison with agglomeration in a homogeneous ultrasonic field for droplets with a size of 0.2 ... 0.6 μm is increased by 25 %, for 1.8 μm droplets by 20 %; and for droplets larger than 2.5 μm, the increase in efficiency is no more than 17 %. [ABSTRACT FROM AUTHOR]

A new design of a high-frequency piezoelectric transducer with a power from 70 to 1800 W (designed for radiation into liquids and gases of ultrasonic (US) vibrations in the frequency range of $30,\ldots,100$ kHz) is proposed. It is based on the principle of summation on a diametrically vibrating summing plate of vibrations of radially mounted Langevin transducers. The method of their design was created and the optimal design dimensions of the transducers were established. This made it possible to manufacture and research practical designs of transducers at frequencies of 30 and 90 kHz. The created transducers together with disk radiators allowed creating US vibrations of 155 dB in the gas at a frequency of 31.67 kHz and 151 dB at a frequency of 92.82 kHz. In this case, the power of the generated vibrations was limited by existing radiators of disk form and a small wave resistance of gas. As a result, the transducers provided radiation up to 1800 W at a frequency of 31.67 kHz and up to 250 W at a frequency of 92.82 kHz of acoustic power. The transducer can be used at processing of liquids, such as dispersion, emulsification, extraction, degassing of liquids, sterilization, and homogenization. The transducer can be used for agglomeration of suspended dispersed particles in gases, drying of various materials, and liquid spraying when exposed to gases. There are no restrictions on the number of simultaneously operating transducers. However, the overall dimensions exclude tight packaging. Therefore, its use in any array with a wavelength-oriented separation is not possible. [ABSTRACT FROM AUTHOR]

The aim of this work is improving the efficiency of chemical technology processes implemented in high viscosity or non-Newtonian fluids by evaluating modes and conditions of ultrasonic action, which provide an increase in the volume of the formed cavitation area. As a result of the research, a theoretical model of cavitation area formation in the non-Newtonian medium has been developed. The analysis of the model allows to calculate the optimal intensity of ultrasonic action (for linear-viscous fluids, the optimal intensity ranges from 1.6 to 80 W/cm2; for nonlinear-viscous fluids up to 120 W/cm2) and the distance (60-125 cm) between the irradiating surface and the reflecting boundary providing the maximum cavitation area volume. Last stage of presented studies the model was confirmed experimentally. [ABSTRACT FROM AUTHOR]

The article is devoted to the solution of problem of providing of high-productive fine-dispersed ultrasonic atomization due to the development of the new construction of the piezoelectric vibrating system of the ultrasonic atomizer intended for the operation at the frequencies of 120...250 kHz. The result of the study is the development and practical realization of the ultrasonic vibrating system providing the generation of high-dispersed aerosols with the size of the drops of 10...17 µm at the atomization productivity of 54 ml/min for 120 kHz and 14 ml/min for 250 kHz at consumed power of no more than 10 W for 120 kHz and 3 W for 250 kHz. The essential improvement of the atomization parameters was achieved due to the increase of area of the atomizing surface (2 cm2 for 120 kHz and 0.5 cm2 for 250 kHz) and providing of the vibration amplitudes of up to 15 µm at the frequency of 120 kHz and 10 µm at 250 kHz. [ABSTRACT FROM AUTHOR]

The article is devoted to the solution of problem of providing of high-productive fine-dispersed ultrasonic atomization due to the development of the new construction of the piezoelectric vibrating system of the ultrasonic atomizer intended for the operation at the frequencies of 120...250 kHz. The result of the study is the development and practical realization of the ultrasonic vibrating system providing the generation of high-dispersed aerosols with the size of the drops of 10...17 µm at the atomization productivity of 54 ml/min for 120 kHz and 14 ml/min for 250 kHz at consumed power of no more than 10 W for 120 kHz and 3 W for 250 kHz. The essential improvement of the atomization parameters was achieved due to the increase of area of the atomizing surface (2 cm² for 120 kHz and 0.5 cm² for 250 kHz) and providing of the vibration amplitudes of up to 15 µm at the frequency of 120 kHz and 10 µm at 250 kHz. [ABSTRACT FROM AUTHOR]

Results of development of piezoelectric ultrasonic radiators (in form of flexural-vibrating titanium disks) for gas mediums are presented in this article. Results of investigations of usage efficiency of these radiators for fogs destruction are pointed. These radiators allow creating maximal level of sound pressure in range from 140 to 150 dB, in frequency range 27±2.0 kHz and ensure reducing a self-destruction time of fogs into aerosol chamber up to 11.5 times. [ABSTRACT FROM AUTHOR]

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 m², four radiators with area of 0.11 m² or six radiators with area of 0.08 m² 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. [ABSTRACT FROM AUTHOR]

This paper presents the results of studies on functional possibilities of the optimization of geometric sizes and the design development of specialized resonance concentrating link (concentrator-sonotrode) with enlarged radiating surface. Developed theoretical model allows to determine the value of longitudinal and transverse sizes of each part of concentrating link providing the achievement of required features of the ultrasonic vibrating systems (gain factor of the unit and its resonance frequency). To verify the efficiency of designed model, the geometric sizes of resonance concentrating link were determined using the finite-element complex, which showed that the disagreement did not exceed 10%. The efficiency of proposed model at the determining of size and resonance characteristics of concentrating link was proved by the experiments. Theoretical and experimental studies helped to optimize the size of concentrating link while the vi- brating system developed on its base enabled the enlargement of radiating surface without decreasing the radiation intensity for the realization of technologies of cavitation treatment of liquid media [ABSTRACT FROM AUTHOR]

The article is devoted to the results of modeling of the formation of cavitation area under ultrasonic influence on liquid media, which differ in flow curves and acoustic properties. Taking into account influence of liquid viscosity on the formation of cavitation area it helps to determine the modes (intensity) and conditions (the size of technological volume) of influence. [ABSTRACT FROM AUTHOR]

• Power transducers 1900 W at 30 kHz and 270 W at 90 kHz in the formation of oscillations in liquids. • The increase in power is provided by summing the powers of individual Langevin transducers on the radiating element. • The radiating element is an adder and a converter of diametrical vibrations into longitudinal vibrations. This article presents the results of the development and study of an ultrasonic radiator (US radiator) of increased power, which is designed for control, location, cavitation processing of liquids, and coagulation of foreign particles in a gaseous media at frequencies from 30 to 90 kHz. The proposed method of vibration summing of low-power high-frequency Langevin transducers on a diametrically vibrating the summing radiating element (summator) allowed developing such a US radiator. The selecting of shape and the search of optimal dimensions allowed creating real designs of US radiator with operating frequency up to 90 kHz. It can generate exposure intensity of 45 W/cm2 at the US radiator power up to 1900 W and an operating frequency of 30 kHz or exposure intensity of 34.6 W/cm2 at the US radiator power up to 270 W and an operating frequency of 90 kHz at cavitational processing of liquids. [ABSTRACT FROM AUTHOR]