Ultrasonic Cavitation Treatment Research Articles

Theoretical modeling and experimental investigation of a V-shaped traveling wave piezoelectric transducer for ultrasonic cavitation Peening: Part A

Ultrasonic cavitation peening is a surface enhancement technology that can increase surface hardness without obviously introducing a high surface roughness of the treatment surfaces. However, the most commonly used traditional transducers for ultrasonic cavitation peening are operated in the longitudinal mode and generate a standing wave in the working gap between a sonotrode end and a treated surface, causing a small cavitation treated area and low efficiency for treating the axis components. To achieve a high efficiency on the surfaces of axis components, a new V-shaped traveling wave transducer is proposed in this paper. Two Langevin transducers are employed to couple on the ring sonotrode, generating two third order in-plane bending vibrations with a spatial phase difference of 90° in the ring. Therefore, same elliptical vibrations are generated in all points on inner surface of the ring, resulting in a uniform cavitation effect around the axis component which is located in the center of the ring sonotrode. It is the first time to propose that cavitation bubbles are generated utilizing traveling waves. An analytical model is created utilizing the transfer matrix method for the vibrating system to describe the dynamic behavior and predict the acoustic field of the working area in the ring sonotrode. To validate the developed transfer matrix model, experimental investigations were conducted to measure the vibration characteristics of the proposed transducer and compared to the transfer matrix model calculation results. For further proving the feasibility of the cavitation peening, sonochemiluminescence was carried out to evaluate the distribution of cavitation bubbles in the working area. The results show that calculation results have a good agreement with the experimental results and a higher voltage and smaller working gap were beneficial for the ultrasonic cavitation treatment utilizing this novel transducer.

Studying the Influence of Acoustic Cavitation and Avalanche-Streamer Discharge on the Quality of Raw Milk in Order to Achieve the Pasteurization Effect

The article presents the results of the studies obtained in the investigation of the quality of milk processed with the use of physical methods of exposure - acoustic cavitation and avalanche-streamer discharge, in order to achieve a pasteurizing effect. It is shown that in the treatment of high-frequency ultrasonic oscillations (over 45 kHz) generated by an electric ultrasonic device of the submersible type of impulse action ”Activator-150”, the number of bacteria of the E. coli group decreased by almost 40%, which allows concluding that the chosen method of influence is effective for the destruction of sanitary and pathogenic (indicative) microflora in raw milk and achieve a certain pasteurization effect. Using low-frequency ultrasonic exposure (20-22 kHz) generated by the cavitation ultrasonic flow type reactor RKU, the raw milk indicators QMAFAnM (Quantity of Mesophilic Aerobic and Facultative Anaerobic Microorganisms) and number of Coliform bacteria did not change after processing, as well as physical and chemical indicators, apart from the indicators of particle fineness. It can be stated that low-frequency ultrasonic cavitation treatment is not effective in terms of achieving a pasteurizing effect. In order to achieve a pasteurization effect by applying avalanche-streamer treatment we assessed its effect on QMAFAnM - the microbiological background of milk. The use of avalanche-streamer discharge does not have the expectation effect on the total number of microorganisms in milk. It is advisable to use high-frequency acoustic cavitation for microbial biota inactivation and avalanche-streamer discharge to reduce spore bacteria contamination.

Creation of Structural Polymer Composite Materials for Functional Application Using Physicochemical Modification

The various aspects of physicochemical modification of the components of structural materials of functional application based on classical composites and nanocomposites are analyzed. Potential applications of such materials are briefly described. Ultrasonic cavitation treatment is considered as a basic method of physical modification when obtaining the indicated classes of composites. The influence of ultrasonic treatment modes on the technological and operational properties of reactoplastic polymers, as well as on the hardening of reinforced composites based on them, is investigated. Technical means of ultrasonic cavitation processing of liquid binders and polymer composites based on them are briefly described. An effective spectrum of interrelated structural and technological parameters of ultrasonic treatment has been characterized, which is established by calculation and experimentally-statistically. The design issues of the technological processes of obtaining polymer composites of functional application are analyzed. The efficiency of creating carbon fiber composite materials, as well as the prospects for creating of these materials based on reinforcing fabric with nanomodified fillers, is described. The methods of obtaining functional nanomodified carbon-composites with improved physicomechanical and operational properties, in particular with increased strength and electrical conductivity, are characterized. The effectiveness of the ultrasonic treatment and production of nanomodified thermoplastic composite materials by extrusion method is considered. Some issues of forming products from intelligent polymer composites are analyzed. The results of the survey can be used in the design of advanced technologies for the creation of functional polymer composites of functional application.

Comparison of hydrodynamic and ultrasonic cavitation effects on soy protein isolate functionality

In this study, soy protein isolate (SPI) dispersions (3%, w/v) were treated with hydrodynamic cavitation (HC) with a venturi tube (treatment volume: 2 L) and ultrasonic cavitation (UC) (treatment volume: 200 mL and 2 L) under the power of 550 W for 5, 10, 20, and 30 min. The effects of HC and UC treatment on the physicochemical and functional properties of SPI were investigated, and the results were compared to better evaluate the HC effects on food proteins. The results showed that the electrophoretic profile and pH were not affected by UC or HC treatment. The particle size and viscosity of SPI were reduced after UC or HC treatment. Both UC and HC treatment significantly (P < 0.05) increased the surface hydrophobicity. UC treatment at the volume of 2 L did not alter the exposed or total sulfhydryl content; however, UC treatment at the volume of 200 mL and HC treatment altered the exposed sulfhydryl content and decreased the total sulfhydryl content. Moreover, the solubility, emulsifying activity index, emulsion stability index, and foaming capacity were also significantly (P < 0.05) improved; however, foam stability was reduced after UC and HC treatment. Under the conditions investigated in this study, the effect of HC treatment on the physicochemical and functional properties of SPI was more pronounced than that of UC treatment at the volume of 2 L, and was similar to that of UC treatment at the volume of 200 mL. These results suggest that HC could be an effective method to improve the functional properties of food proteins.

Study on the therapeutic efficacy of subcutaneous pancreatic cancer xenograft tumor with ultrasound destruction of different size microbubbles

Objective To assess the therapeutic efficacy of subcutaneous transplantation pancreatic cancer in nude mice model with different size microbubbles. Methods Eighteen Balb/C nude mice with subcutaneous pancreatic carcinoma xenografts were divided into three groups: group A(6 mice) did not received microbubbles and ultrasonic irradiation; group B(6 mice) received standard microbubbles and ultrasonic cavitation treatment; group C(6 mice) received up-sized microbubbles and ultrasonic cavitation treatment. Body weight and tumor size of nude mice were measured respectively at the time points of 0, 7, 14, 21 days after three times ultrasound radiation and before ultrasound treatment. Tumor volumes were calculated.Then the mice were sacrificed finally. Results There was no significant difference in tumor volumes among three groups before treatment(P>0.05). Tumor volume continued to increase in all groups. Compared with group A, growth rate in group B and group C were lower, growth rate in group B was higher than that in group C, the difference was statistically significant(P 0.05). RBV and RBF were decreased significantly after 3 days treatment in group B and group C(P 0.05). Conclusions The cavitation effect of up-sized microbubbles is more efficient for mice subcutaneous pancreatic cancer xenograft tumor inhibition compared with standard microbubbles. Key words: Sonication; Pancreatic neoplasms; Microbubbles; Neoplasms, vascular tissue

Effect of ultrasonic cavitation treatment on liberation and hydrocyclone separation of bituminous coal

Testing was conducted to evaluate the effects of hydroacoustic cavitation (HAC) treatment on two bituminous coal slurries and the subsequent separation of each slurry in a classifying hydrocvclone. HAC treatment was performed using a pilot-scale circuit fabricated by Fumess-Newb urge Inc. The circuit was designed to induce cavitation by means of flow through an ultrasonic resonator chamber or enhanced cavitation by initial flow through a cavitation chamber followed by flow through the ultrasonic chamber. The test materials were nominal −1,500-micron and −150-micron lllinois-basin bituminous coal slurries, which were obtained from an operating coal preparation facility. After 5 sec of HAC treatment, the median size of the −1,500-micron material was reduced, with ash values for certain size fractions decreasing more than 5 percent compared with untreated samples. Extending treatment time led to greater degradation of the +1,180-micron material and an increase in the −25-micron material, with ash reductions occurring for material in the −850+150-micron size range. Size degradation was less for the −150-micron material. Subsequent separation of the treated slurries was carried out in a hydrocvclone with diameter of 102 mm. HAC treatment led to a decrease in the ash value and an increase in the heating value of the underflow stream compared with the feed material. For example, the ash value was reduced by about 16 percent for the −1,500-micron material and 25 percent for the −150-micron material with heating value increases of 7 and 33 percent, respectively, after HAC treatment. Overall, HAC treatment appeared to have a slight effect on the size selectivity curves.

Application of the "Full Cavitation Model" to the fundamental study of cavitation in liquid metal processing

Ultrasonic cavitation treatment of melt significantly improves the downstream properties and quality of conventional and advanced metallic materials. However, the transfer of this technology has been hindered by difficulties in treating large volumes of liquid metal. To improve the understanding of cavitation processing efficiency, the Full Cavitation Model, which is derived from a reduced form of the Rayleigh-Plesset equation, is modified and applied to the two-phase problem of bubble propagation in liquid melt. Numerical simulations of the sound propagation are performed in the microsecond time scale to predict the maximum and minimum acoustic pressure amplitude fields in the domain. This field is applied to the source term of the bubble transport equation to predict the generation and destruction of cavitation bubbles in a time scale relevant to the fluid flow. The use of baffles to limit flow speed in a launder conduit is studied numerically, to determine the optimum configuration that maximizes the residence time of the liquid in high cavitation activity regions. With this configuration, it is then possible to convert the batch processing of liquid metal into a continuous process. The numerical simulations will be validated against water and aluminium alloy experiments, carried out at Brunel University.

Correlation vs. Causation: The Effects of Ultrasonic Melt Treatment on Cast Metal Grain Size

Interest in ultrasonic treatment of liquid metal has waxed and waned for nearly 80 years. A review of several experiments representative of ultrasonic cavitation treatment of Al and Mg alloys shows that the theoretical mechanisms thought to be responsible for grain refinement are (1) cavitation-induced increase in melting temperature predicted by the Clausius-Clapeyron equation and (2) cavitation-induced wetting of otherwise unwetted insoluble particles. Neither of these theoretical mechanisms can be directly confirmed by experiment, and though they remain speculative, the available literature generally assumes that one or the other or both mechanisms are active. However, grain size is known to depend on temperature of the liquid, temperature of the mold, and cooling rate of the entire system. From the reviewed experiments, it is difficult to isolate temperature and cooling rate effects on grain size from the theoretical effects. Ultrasonic treatments of Al-A356 were carried out to isolate such effects, and though it was found that ultrasound produced significant grain refinement, the treatments also significantly chilled the liquid and thereby reduced the pouring temperature. The grain sizes attained closely correlated with pouring temperature suggesting that ultrasonic grain refinement is predominantly a result of heat removal by the horn and ultrasonic stirring.

Studies on Pre-Treatment of Wastewater Containing Nitroaromatic Compound by Ultrasonic Cavitation

In this paper, ultrasonic cavitation degradation was applied to treat the wastewater containing nitroaromatic compound. The factors influence to treatment effect such as the ultrasonic power and frequency, the wastewater initial pH value, were investigated by experiment. The experimental results showed that air-blasting in ultrasonic cavitation treatment could effectively improve treatment effect. The wastewater（COD:2650 mg•L-1,BOD5:240 mg•L-1，p-nitroaniline：490 mg•L-1，nitrobenzene:100 mg•L-1）was treated by ultrasonic cavitation degradation, the removal rate of p-nitroaniline,nitrobenzene and COD could be reached 91.3%,90.6% and 83.9% respectively after 3h. Biodegradability of the wastewater (B/C ratio ) can be increased to 0.4 , which satisfied the requirement for the subsequent biochemical processes.

Ultrasonic cavitation treatment for soldering on Zr-based bulk metallic glass

The joining behavior of solder on a Zr-based bulk metallic glass (BMG) surface without a soldering flux was studied under controlled ultrasonic cavitation in molten Sn–Cu–Ni solder at 528 K (open to air). Characteristic physical phenomenon appeared at the solder wetting interface when cavitation bubbles collapsed on the surface of the BMG substrate; this forced the wetting of the BMG surface with solder. The collapsing of the cavitation bubbles on the BMG surface-induced severe erosion. This cavitation erosion is effective in the immediate removal of passive film from the BMG substrate surface. The sono-capillary effect that is also induced by the ultrasonic vibration enhanced the adhesion property of the solder. Based on these results, an ultrasonic soldering method is proposed and its joining process is also investigated in detail.

Some control mechanisms of spatial solidification in light alloys

Two unconventional approaches of controlling the size and distribution of primary particles in aluminium and magnesium alloys are suggested. The first approach uses the ultrasonic cavitation treatment for multiplication of solidification sites for primary crystals by activating catalytic impurities that are present in the melt. The second way, on the contrary, involves elimination of active solidification nuclei by melt overheating with subsequent nucleation of primary particles at a higher undercooling. Both approaches result in refinement of primary crystals.

Production of natural and synthesized aluminum-based composite materials with the aid of ultrasonic (cavitation) treatment of the melt

The application of ultrasonic melt treatment to the production of natural and synthesized aluminum-based composite materials is considered in terms of underlying basic ideas and commercial implementations. It is shown that the ultrasonic cavitation treatment combined with microalloying of hypereutectic Al–Si natural composites (alloys) promotes the formation of structures suitable for further deformation. The use of highly impure starting materials becomes also possible. The combination of ultrasonic cavitation treatment with electromagnetic stirring allows one to considerably improve the size and spatial distribution of ceramic particles in metal–matrix composites.