Influence Of Ultrasonic Vibrations Research Articles

Increasing the efficiency of coagulation in resonant gaps due to acoustic flow formation

Relevance. The urgent need to eliminate environmental pollution from industrial emissions of various solid particles. At the same time, maximum attention is paid to cleaning exhaust gases from particles of 2.5 microns in size or less. One of the most promising ways to increase the efficiency of existing gas purification equipment in capturing such particles is their coagulation by exposing the gas flow to high-intensity acoustic vibrations of ultrasonic frequency. However, at low concentrations, even at the maximum permissible sound pressure level, the coagulation efficiency of particles smaller than 2.5 microns is insufficient to increase the recovery rate of gas cleaning equipment. Therefore, there is an urgent need to find new ways to further improve the efficiency of ultrasonic coagulation of particles smaller than 2.5 μm. Aim. To determine the conditions for the formation of vortex flows in ultrasonic fields with the maximum ultrasonic influence in terms of sound pressure level. Conducting comparative studies of the coagulation of particles with a size of 2.5 microns with and without vortex flows. This will make it possible to determine the real values of increasing the efficiency of ultrasonic coagulation during turbulization of a gas-dispersed flow by acoustic flows in comparison with coagulation in a uniform ultrasonic field and without it. Objects. Coagulation of particles under the influence of homogeneous and inhomogeneous ultrasonic fields. Methods. Computer modeling of the formed ultrasonic field by the finite element method using harmonic acoustic analysis. The paper considers the experimental method for studying the process of combining particles under the influence of ultrasonic vibrations. To determine the characteristics of an aerosol during experimental studies, a TIPAS-1 meter based on the small-angle scattering method and the spectral transparency method was used. Results. The paper introduces the results of studies of coagulation of particles with a size of 2.5 microns or less in an ultrasonic field formed in resonant gaps by oscillating disk emitters. The authors proposed to increase the efficiency of coagulation in resonant gaps through the use of ultrasonic disk emitters capable of forming alternating zones of maximum and minimum amplitude oscillations in the resonant gaps. The creation of such zones ensured the formation of vortex-type acoustic flows capable of moving particles within the nodal regions of a standing wave and between them. The involvement of small particles in the formed flows made it possible to increase the probability of their collision. It was established that more effective ultrasonic coagulation provides an increase in the degree of inertial capture for particles of 2.5 microns in size by 6% – from 89 to 95%, for particles of 1.5 microns in size by 7% – from 85 to 92%, and for particles of 0.5 microns by 9% – from 76 to 85%.

Анализ течений при лазерно-акустической обработке нержавеющей стали AISI 316L

The influence of ultrasonic vibrations on the flow of molten metal during laser processing is investigated. This problem is of interest within the context of modernization of existing technological processes, such as laser welding and cladding, for the production of structures with improved physical and mechanical properties. The introduction of additional ultrasonic energy into the liquid metal bath intensifies the metal flow via forced stirring, which provides its homogenization and leads to an increase in the mechanical properties of the processed material due to the growth of the number of crystallization centers during its solidification. In order to get a better understanding of this combined process and to control it, a method for synthesizing hydrodynamic and strength solvers used in the ANSYS software package is proposed. Setting up the coupling between two corresponding ANSYS Transient Structural and ANSYS CFX modules is executed through the additional ANSYS System Coupling module. Under this numerical implementation of the problem, it is possible to calculate the displacements at the solid metal boundary and their transfer to the liquid metal boundary and vice versa at each moment of time. The impact of laser radiation on the liquid metal is considered taking into account Marangoni convection, and convection and radiation heat transfer. The results of numerical experiments make it possible to conduct a qualitative and quantitative comparison between the liquid AISI 316L stainless steel flows formed without and with ultrasonic vibration. It is shown that the intensification and deceleration of the flows is observed at the average values of the ultrasonic amplitude. This fact correlates with the moments of time at which the deformed surface of the metal in the bath moves down and up. A comparative analysis of the maximum axial velocities inside the liquid metal bath was conducted. The absence of ultrasonic action on the liquid metal motion was observed at the maximum values of the vibration amplitude, which correspond to the maximum displacement and deformation of the surface at the interface between liquid and solid.

Influence of Ultrasonic Vibrations on the Formation of a Welding Seam

Influence of Ultrasonic Vibrations on the Formation of a Welding Seam

Influence of ultrasonic vibrations on the formation of a weld seam

The methods of ultrasonic influence on the formation of welds are analyzed. The processes occurring in a weld as a result of ultrasonic vibrations are studied. Positive factors of ultrasonic influence are established that improve the quality of welded joints. Keywords:welding, weld seam, ultrasound, vibrations, structure, properties, quality sergey-lefmo@yandex.ru

Influence of ultrasonic vibrations on the temperature of the dried material

Influence of ultrasonic vibrations on the temperature of the dried material

Borophene: a piezocatalyst for water remediation.

Borophene is an emerging two-dimensional material exhibiting exceptional piezocatalytic activity under the influence of ultrasonic vibrations, as exemplified herein by the decomposition of highly stable organic dyes in water. After 6 minutes of exposure, borophene sheets converted up to 92 percent of a mixture of dye molecules at room temperature.

The Effect of the Distance between Ultrasonic Horn and Torch on the Microstructure of Ultrasonic-Assisted Gas Tungsten Arc Welded Inconel 690 Alloy Joint

The study focuses on investigating the relationship between the ultrasonic effect and microstructure of ultrasonic-assisted gas tungsten arc welding (UA-GTAW) Inconel690 alloy joints. The influence of ultrasonic vibrations on Inconel690 plates was examined, while also clarifying the distribution pattern of the ultrasonic effect across the plate. Furthermore, actual welding experiments were performed by varying the distance between the ultrasonic horn and the welding torch. The results revealed that there were changes in both grain growth direction within the weld zone and refinement effects achieved under different distances. The optimal refinement of primary and secondary dendrite arm spacing was observed at distances of 60 mm and 180 mm between the welding torch and ultrasonic horn. The hardness of weld zone reached 235HV1 when the distance between ultrasonic horn and welding torch is 180 mm.

Effect of high-intensity ultrasonic field on fog droplet coagulation efficiency

The relevance. The urgent need to deal with fog for preventing limited visibility and creating improved meteorological conditions. Exposure to gas dispersed systems by mechanical vibrations of the ultrasonic frequency can be considered as the most effective way to deal with fog formation. However, the acoustic method has not found an industrial application for fog destruction mainly due to the lack of effective sources of acoustic exposure. Therefore, it is necessary to create emitters of higher power that provide a significantly greater range of radiation with a sound pressure level of at least 140 dB and study of their functionality. The main aim. Determination of the effectiveness of fog destruction through the use of ultrasonic vibrations generated by the developed ultrasonic emitters; identification of the most promising design of ultrasonic equipment that ensures effective destruction of fogs in open areas. Objects. Combining fog droplets under high-intensity ultrasonic exposure using specially designed ultrasonic emitters for gas media of four types. Methods. Experimental method for studying fog droplets combination under the influence of ultrasonic vibrations and their gravitational deposition. To determine the aerosol (water content and disperse composition) characteristics, during experimental studies, the authors have used the TIPAS-1 meter based on the method of small-angle scattering and the method of spectral transparency. Results. The authors established and shown the effectiveness of ultrasonic effect on fogs, as well as the possibility of its use for fog destruction in an open area. All developed disc ultrasonic emitters are capable of forming a sound pressure level within 140... 145 dB at 22±2.0 kHz. The time of fog natural destruction in the aerosol chamber is reduced by up to 11.5 times. The results obtained demonstrate that it is necessary to use more powerful disc emitters, since they can significantly reduce the time of fog destruction and increase the volumes voiced at the same time. The minimum time for establishing the required metrological range of visibility is provided by means of a directional emitter with a stepped-variable surface, forming a flat wave.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ УЛЬТРАЗВУКА НА ФОРМИРОВАНИЕ СТРУКТУРЫ И СВОЙСТВ СОЕДИНЕНИЯ АЛЮМИНИЯ СО СТАЛЬЮ ПРИ СВАРКЕ ВЗРЫВОМ НА ФОРСИРОВАННЫХ РЕЖИМАХ СОУДАРЕНИЯ

The work is devoted to the study of the effect of the introduction of ultrasonic vibrations during explosion welding of a pair of aluminum-steel compounds. A comparative study of the effect of the explosive loading scheme of joints obtained by the conventional method of explosion welding and explosion welding with the influence of ultrasonic vibrations in forced welding modes was carried out. It has been experimentally established that the introduction of additional ultrasound energy in the process of explosive loading of an aluminum-steel compound contributes to a significant reduction in the amount of molten metal at the junction boundary throughout the studied range. The chemical composition of the areas of the melted metal is considered. The results of the tensile strength of aluminum+steel composite layers are presented.

Multi-dimensional ultrasonic-assisted belt grinding on the surface integrity of Inconel 718

In order to meet the requirements of the isotropic high-performance machining of complex surfaces, this paper proposed three-dimensional ultrasonic assisted belt grinding (3D-UABG) method that integrates the advantages of surface strengthening and isotropic machining, analyzed the motion characteristics and surface formation laws. Then, the influence of ultrasonic vibrations on the surface integrity of Inconel 718 was studied by a self-designed 3D-UABG device. Finally, the surface formation mechanism was revealed combined with the surface integrity and abrasive grain motion characteristic. Results showed that compared with conventional abrasive belt grinding (CABG), the abrasive grain in normal-ultrasonic assisted belt grinding (N-UABG) reduced the height of texture peak formed an intermittent texture, which makes it have smallest surface roughness. At the same time, the high-frequency impact of abrasive grains not only increased the surface plastic deformation, but also realized the impact strengthening. Planar two-dimensional ultrasonic assisted belt grinding (2D-UABG) reduced the directionality difference of surface quality. However, the deflection characteristics of abrasive grains make it have a large surface roughness. The 3D-UABG surface has good comprehensive mechanical properties. The abrasive grains have three-dimensional dynamic characteristics in space, which effectively inhibit anisotropic stress state, promote uniform deformation, and helpful to obtain approximately isotropic surface texture and small surface roughness. On the one hand, the in-plane motion characteristics of planar two-dimensional ultrasonic vibration gave grinding surface more uniform surface integrity. On the other hand, the spatial motion trajectory of abrasive grains driven by three-dimensional ultrasonic vibration made it have a slow increased cutting depth, which avoided the tear damage caused by materials plastic accumulation and the large roughness caused by abrasive deflection under large cutting depth. In 3D-UABG, lower feed speed and amplitude and linear velocity matched to grinding parameters contribute to the improved surface integrity. This study has guiding significance for the development and engineering application of ultrasonic-assisted belt grinding technology.

Влияние ультразвуковых колебаний с наложенной низкочастотной модуляцией на механические, трибологические свойства и структуру многокомпонентного полимерного композита

One of the tasks of polymer materials science is to study the possibilities of improving the complex of elastic-strength characteristics and tribological properties of polymer composite materials by improving the manufacturing technology. In this paper, the influence of ultrasonic vibrations with a frequency of 17 kHz with a low-frequency vibration with a frequency of 100 Hz during synthesis on the properties and structure of a multicomponent polymer composite material of the KVN-3 trademark is considered. The result of the research, it is found that the influence of the technological mode of pressing, consisting in the combined effect of ultrasonic vibrations with frequency and low-frequency vibration during the synthesis of KVN-3, makes it possible to increase the complex of elastic-mechanical characteristics: tensile strength by 3 %, elongation by 6 %, modulus of elasticity by 10 %, hardness by 2 %, compared to the industrial manufacturing method, as well as to reduce the intensity of mass wear by 68 % and the coefficient of friction by 3 %. The structure of polymer composite materials after different technological pressing modes is examined. The fibrillar structure of the polymer matrix after the technological regime with the influence of ultrasonic vibrations and low-frequency modulation becomes finer and more uniform.

Influence of ultrasonic vibrations during drilling of carbon-fiber-reinforced polyetherimide composites

Carbon-fiber-reinforced polyetherimide (CFRP) is an advanced composite material that has a high strength-to-weight ratio, better fatigue, high mechanical strength, low friction coefficient and low weight. Drilling of composite is difficult due to the anisotropic and inhomogeneous structure of fiber and matrix that affects micro and macro geometrical damages. Conventional drilling of CFRP composite causes high temperature, cutting force, torque, fiber pull-out, damaged surface topology, microcracks and delamination. The present study leverages rotary ultrasonic-assisted drilling of CFRP composites and comparison with rotary drilling and normal drilling. The influence of different drilling parameters was investigated on cutting force, temperature, torque, surface roughness, material removal rate and microcracks produced at the drilled edge surface. It was observed that a rotational speed of 2500 rpm, 10 mm/min of feedrate, 420 µm of diamond grit sizes and ultrasonic power of 100 % for minimizing the cutting force, surface roughness, and torque. The rotary ultrasonic-assisted drilling of CFPR composite produces a precise cut with smooth surface morphology as compared to rotary drilling and normal drilling of composites. The application of rotary ultrasonic-assisted drilling using diamond-impregnated hollow tools can be leveraged for various industrial applications to avoid microcracks and fiber delamination.

Influence of ultrasonic vibrations on the properties of press-and-sintered titanium

In this study, longitudinal ultrasonic vibration was superimposed during the compaction of titanium powders. Then, specimens were vacuum sintered at 1273 K for 120 min. In order to investigate vibration influence on physical/mechanical properties, density, shrinkage, and compression strength of sintered samples were measured. The influence of powder size, compaction pressure, and aspect ratio also were studied on mentioned physical properties. Improvement of fine powder sintered samples density due to applied ultrasonic is greater than coarse powders, although their compacted density is lower than coarse powders samples. Dimensional stability (in the opposite of shrinkage) in coarse powder is greater than fine powders so that shrinkage in fine powders decreases up to 12%. Compression strength is improved due to the application of ultrasonic vibration up to 64%.

Effect of ultrasonic welding process parameters on seam strength of PVC-coated hybrid textiles for weather protection

Using a lapped seam, PVC-coated hybrid textiles with uniform thickness were bonded by continuous ultrasonic welding and conventional joining method with the help of hot air tape welding technique for weather protection purposes. Three fundamental sewing parameters at two distinct levels and three primary welding parameters at three levels based on 6 and 12 mm welding widths were used. To consider the effect of welding and sewing parameters on seam strength, full factorial designs of experiments were designed, fabricated, and tested. The thermal behavior and possibility of chemical conversion in the welding zone under the influence of ultrasonic vibrations were examined. Variation in width of heat-affected zone of weld seam was measured. The seam strength of ultrasonic weld seam compared with that of conventional seams, and superior seam strength yielding parametric levels were assessed. The parametric influence of both joining techniques on seam quality and their tendencies in the relationship were analyzed statistically. The weld seam strength (1256.392 and 2116.93 N/50 mm) was optimized numerically and identified its trend with the variation of the weld seam. The discovered relationship led to the conclusion that the variation in the weld seam can be used to estimate the tensile strength of the weld seam through the developed effective numerical model as a non-destructive testing method, and its outcome was successful as a destructive testing method. The result shows that the ultrasonic weld seam provided a higher tensile strength ( > 75%) than the conventional seam for both evaluated welding widths and obtained statistically significant results.

Intensification of heat exchange by an ultrasound source for milk pasteurization.

The goal of this article is to investigate the effect of ultrasonic vibrations on the process of milk pasteurization. Ultrasound can potentially intensify heat transfer and reduce the formation of thermal sediment (soot deposit) on the walls of heat-exchange devices. The paper presents the results of experimental studies demonstrating the growth rate of thermal sediment on the wall of the heat-exchange apparatus and its amount in the volume of milk under the influence of ultrasonic vibrations and without it.

The influence of ultrasonic vibrations on material removal in the silicon wafer polishing using DDCAMRF: Experimental investigations and process optimization

The present experimental investigation attempts to understand and address the effect of ultrasonic vibrations on material removal in the polishing of silicon wafers (1 0 0). The requisite finishing experimentations were performed on an indigenously developed experimental arrangement of double-disc chemical assisted magnetorheological finishing (DDCAMRF) process with longitudinal vibrations. The MR fluid used in the experiments consists of a water-based suspension prepared by mixing suitable amounts of carbonyl iron particles (CIPs), abrasive particles, and additives or stabilizers. The prepared MR fluid uses both mechanics and chemistry to finish the silicon surface. Mechanics is mainly responsible for micro-scratching of silicon surface, which gets “softened” by hydration utilizing DI water in the MR fluid. In this study, the ‘response surface methodology (RSM)’ was chosen for designing the experiments to evaluate the significance of different process factors, namely polishing speed, abrasive concentration, and ultrasonic power on the material removal rate (MRR) in DDCAMRF process. The material removed from the wafer surface was measured using the precision digital weighing balance. It was observed that the MRR was found to increase with the increase in various process factors used. Further, analysis of variance (i.e., ANOVA) technique with a 95% confidence interval was performed to analyze the significant contribution of different process factors on MRR. The validation of developed model was done by performing experiments on random and optimized set of process factors. From, the statistical investigation it was discovered that ultrasonic power has highest contribution of 57.9% on MRR, followed by the polishing speed (13.3%), and abrasive concentration (12.5%). Furthermore, a genetic algorithm optimization tool was utilized to obtain optimum set of process parameters to maximize MRR.

IMPROVEMENT OF GAS MONITORING METHODS IN WATER OF THE HYDROGEN-WATER COOLING SYSTEM OF NPP’S TURBINE GENERATOR

The relevance of research is to ensure and improve the reliability of turbine generators (TG) with a hydrogen-water cooling system by monitoring the content of dissolved gases in the water of a hydrogen-water cooling system with monoethanolamine (MEA) – C2H7NO and water vapor in the cooling hydrogen of the turbine. In this work, the influence of ultrasonic vibrations on the decomposition of a mixture of water and turbine oil, organic acids (acetic acid - С2Н4О2, formic acid - СН2О2, oxalic acid - С2Н2О4) or monoethanolamine was determined. The distribution coefficients values were definedd for the following dissolved gases Н2, О2, N2, СО, СН4, С2Н2, С2Н4, С2Н6, С3Н6, С3Н8, which are of degradation products of water mix components when exposed to ultrasonic oscillation in the following system: «dissolved gas – mixture «water + monoethanolamine» – extractant argon (Ar)». The obtained values of the Кі distribution coefficients for dissolved gases in systems «dissolved gas – mixture «water + С2Н7NО» – extractant argon (Ar)» at a temperature of 293 K and a concentration of С2Н7NО at the level of 1 g/dm3 are close to similar values for dissolved gases in deionized water. The principle flow chart of multichannel gas chromatograph for detecting dissolved gases in water and steam of water in hydrogen was developed. Developed flow chart of 4-chennel gas chromatographer for defining dissolved gases in water includes the one gas chromatographer with conductivity detector, methanator, flame ionization detector, argon gas-bearing and supplementary gases of hydrogen and air.

ПОВЫШЕНИЕ ЭФФЕКТИВНОСТИ ПРОЦЕССА НАРЕЗАНИЯ И ОБРАБОТКИ ЗУБЧАТЫХ КОЛЕС

The paper presents data on the influence of ultrasonic vibrations on the processes of cutting gears made of difficult-to-cut materials. It is shown that with the introduction of ultrasound into the processing zone, there is a significant decrease in the component of the cutting force Pz, chip shrinkage and the height of the micro-roughness. The wear of the cutting teeth with the imposition of ultrasonic vibrations becomes more stable, and the efficiency of the tooth-working tool increases.

Development of methods of gas chromatographic analysis of technological media of the main circulation pumps of a nuclear power plant

During the operation of power plant equipment, technological media are used – water, turbine oils. Diagnostics of equipment by chromatographic determination of diagnostic components (gases Н 2 , СН 4 , С 2 Н 6 , С 2 Н 4 , С 2 Н 2 , СО, СО 2 , О 2 , N 2 ), water, Ionol in these media is urgent. For this, 5 chromatographs are used. An increase in the reliability of the main circulation pumps of a nuclear power plant can be due to an increase in the reliability of its system. The influence of ultrasonic vibrations on the generation of gases in the systems oil – diagnostic gas, oil – water – diagnostic gas with the use of turbine Тп-22s is studied. Gas concentrations increase with an increase in the duration of exposure for 1600 s at a frequency of 35–125 kHz and a power of 20 W. The dependences of the concentrations Ci of dissolved gases on the irradiation time τ of technological media is expressed by the equation Сi=А∙τ+В Coefficients A, B and correlation coefficients R2 have specific values for each dissolved gas. So, 0.95≤R2≤0.995, which indicates the adequacy of the obtained equations to the experimental data. This makes it possible to determine turbine in water after irradiation and subsequent chromatographic determination of the generated dissolved gases. The technical requirements for a 5-channel chromatograph were established and its structural diagram was developed. This makes it possible to reduce the number of measurement operations and chromatographs. The thresholds for determining the diagnostic components in the corresponding technological environments have been determined: 2 ррm (Н 2 ); 1 ррm (СН 4 , С 2 Н 6 , С 2 Н 4 ); 0,5 ррm (С 2 Н 2 ); 5 ррm (СО, СО 2 ); 1,5 ppm (О 2 , N 2 ); 0.05 wt. % (Ionol); 2 g/t (water in turbine oil) 0.02 mg/dm3 (turbine in water). The basic technological scheme of the system for the main circulation pumps of the NPP has been developed. It is proposed to continuously: degassing the turbine flow; sorption purification of cooling water, analysis of turbine and cooling water by chromatography methods. This will reduce the degradation of turbine and increase the reliability of the system of the NPP main circulation pumps

Experimental research on the influence of ultrasonic vibrations on the laser cladding process of a disc laser

Disc lasers have a wide range of applications in laser cladding due to a series of advantages such as good beam quality. The cladding layer formed by the disc laser in laser cladding is prone to microcracks, pores and other microscopic defects, which seriously affects the promotion of this technology. Ultrasonic vibration can generate high-frequency and low-amplitude vibrations, which actively affect the formation of the microstructure during the solidification of the cladding layer. They can effectively reduce the formation of microscopic defects. This paper builds an ultrasonic-assisted laser cladding system platform based on a disc laser. We cladded 316L powder onto an ASTM 1045 steel substrate for multiple laser cladding experiments, and performed microscopic characterization and analysis of the cladding layer. The result shows that ultrasonic vibrations can effectively refine the bottom and top microstructures of the cladding layer, especially the morphology of the dendrite arms. The phase structure did not change under different ultrasonic amplitudes. Ultrasonic vibration changes the direction of heat flow inside the molten pool, causing the crystal orientation to change from a (220) crystal orientation to a (111) crystal orientation. This research will provide an important theoretical basis for the precise control and optimization of the cladding process and reduction of the formation of microscopic defects.