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In the ultrasonic dispersion process, the ultrasonic cavitation effect can seriously affect the dispersion efficiency of magnetorheological polishing fluid (MRPF), but the mechanism remains unclear now. Through considering the continuity equation and Vand viscosity equation of the suspension, a revised cavitation bubble dynamic model in the MRPF wa...
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... is an important index to evaluate its performance, and it can indirectly describe the dispersion of the particles [39]. In order to evaluate the ultrasonic cavitation on the dispersion effect of the MRPF, sediment experiments were carried out. The schematic of the experimental apparatus of ultrasonic and mechanical dispersion is shown in Fig. 5. The CIP of solid particles with a strong influence on ultrasonic cavitation was selected for sediment experiments. Various volume fractions of CIP in the MRPF are obtained in Table 2. The experimental conditions of ultrasonic and mechanical dispersion are shown in Table 3. The sedimentation rate was examined after the MRPF was left to ...
Citations
... The factors that affect the process of cavitation erosion in the form of particles include particle size, shape, impact angle, and hardness [45,46]. Guo et al. [47] investigated the possibility of a relationship between the solid particle elements and the ultrasonic cavitation action in magnetorheological polishing fluid (MRPF). They found that the cavitation effect is very slightly affected by a low volume percent of green silicon carbide (GSC), but a large volume proportion of carbonyl iron particles (CIP) significantly decreases it. ...
The primary issues in the Himalayan Rivers are sediment and cavitation degradation of the hydroelectric power turbine components. During the monsoon season, heavy material is transported by streams in hilly areas like the Himalayas through regular rainfalls, glacial and sub-glacial hydrological activity, and other factors. The severe erosion of hydraulic turbines caused by silt abrasion in these areas requires hydropower facilities to be regularly shut down for maintenance, affecting the plant's overall efficiency. This article provides an in-depth examination of the challenges that can lead to cavitation, silt erosion, and a decrease in the efficiency of various hydroelectric turbines, and it demands attention on the design, manufacture, operation, and maintenance of the turbines. This study's main objective is to critically evaluate earlier theoretical, experimental, and numerical evaluation-based studies (on cavitation and silt erosion) that are provided and addressed throughout the study. As a part of this study, various strategies for mitigating the effects of these problems and elongating the time that turbine may be utilized before they must be replaced have been provided.
... Ultrasound has been used in several applications in Chemical and Process Engineering, covering solid-liquid processes, such as effluent treatment [1,2], extraction [3], aggregation [4,5], dispersion [6,7] and crystallization [8][9][10], liquid-liquid process (emulsification [11,12]), gas-liquid process (atomization [13][14][15]), and also in various reaction processes, such as polymerization [16,17], hydrogen production [18][19][20] and sonochemistry [21][22][23][24]. The chemical and physical effects of ultrasound sought in all these processes are linked to the phenomenon of acoustic cavitation [25]: millions of micro-bubbles of gas appear in the liquid under the influence of pressure changes caused by the acoustic wave, and then collapse very violently resulting in a huge concentration of energy (few hundred atmospheres pressure and few thousand Kelvin temperature in the bubbles). ...
... Our model of cavitating liquid can of course be challenged, and several paths of amelioration were proposed in Ref. [43], which we remind quickly here. Louisnard chose to set the real part of the square wave number k 2 NL to its linear value (6) and argued that its precise value was not significant since Ik 2 NL contains the main energy dissipation mechanism and is large [39]. However, later studies showed that Rk 2 NL could be also computed in a nonlinear context [77,78]. ...
This investigation focuses on the influence of geometric factors on cavitational activity within a 20kHz sonoreactor containing water. Three vessels with different shapes were used, and the transducer immersion depth and liquid height were varied, resulting in a total of 126 experiments conducted under constant driving current. For each one, the dissipated power was quantified using calorimetry, while luminol mapping was employed to identify the shape and location of cavitation zones. The raw images of blueish light emission were transformed into false colors and corrected to compensate for refraction by the water-glass and glass-air interfaces. Additionally, all configurations were simulated using a sonoreactor model that incorporates a nonlinear propagation of acoustic waves in cavitating liquids. A systematic visual comparison between luminol maps and color-plots displaying the computed bubble collapse temperature in bubbly regions was conducted. The calorimetric power exhibited a nearly constant yield of approximately 70% across all experiments, thus validating the transducer command strategy. However, the numerical predictions consistently overestimated the electrical and calorimetric powers by a factor of roughly 2, indicating an overestimation of dissipation in the cavitating liquid model. Geometric variations revealed non-monotonic relationships between transducer immersion depth and dissipated power, emphasizing the importance of geometric effects in sonoreactor. Complex features were revealed by luminol maps, exhibiting appearance, disappearance, and merging of different luminol zones. In certain parametric regions, the luminol bright regions are reminiscent of linear eigenmodes of the water/vessel system. In the complementary parametric space, these structures either combine with, or are obliterated by typical elongated axial structures. The latter were found to coincide with an increased calorimetric power, and are conjectured to result from a strong cavitation field beneath the transducer producing acoustic streaming. Similar methods were applied to an additional set of 57 experiments conducted under constant geometry but with varying current, and suggested that the transition to elongated structures occurs above some amplitude threshold. While the model partially reproduced some experimental observations, further refinement is required to accurately account for the intricate acoustic phenomena involved.
... The occurrence of cavitation erosion in the presence of particles is additionally reliant on various factors, including the impact angle, as well as the shape, size, and hardness of the particles [164,165]. For instance, Guo et al. [166] observed that the ultrasonic cavitation effect in magnetorheological polishing fluid (MRPF) is influenced by the properties of solid particles. They found that a high volume fraction of carbonyl iron particles (CIP) considerably weakens the cavitation effect, while a low volume fraction of green silicon carbide (GSC) has only a negligible effect on it. ...
Sediment erosion frequently occurs in areas with high incidences of cavitation. The collaborative impact of abrasion and cavitation presents a host of challenges, threats, and damages to hydraulic engineering. However, little is known about the synergistic wear mechanism, and research conclusions remain inconsistent. In this work, relevant studies on synergistic erosion have been collected, classified, and analyzed. Presently, research on synergistic wear primarily operates at the macro and micro levels. The microscopic level enables the visualization and quantification of the process by which particles gain momentum from bubbles, the trajectory of particle acceleration, and the mechanism that triggers strong interactions between bubble-particle. At the macro level, erosion is understood as the summation of damage effects on the wall that is caused by the interaction between a plethora of bubbles of varying scales and numerous particles. The synergistic bubble-particle effect is reflected in the dual inhibiting or promoting mechanism. Furthermore, while numerical simulations could be realized by coupling cavitation, multiphase flow, and erosion models, their accuracy is not infallible. In the future, the dual role of particles, and particles driven by micro-jets or shock waves should be fully considered when establishing a combined erosion model. In addition, enhancing the influence of flow field and boundary parameters around bubbles and utilizing FSI would improve the predictive accuracy of erosion location and erosion rate. This work helps to elucidate the combined wear mechanism of hydraulic machinery components in sediment-laden flow environments and provides a theoretical basis for the design, manufacture, processing, and maintenance of hydraulic machinery.
... Subsequently, the initial depth of the c the surface roughness were measured. In the next step, the sample was fixed in t device and a given volume (0.12-0.36 mL) of an MR slurry (which was sonicated use to ensure better dispersion properties [39]) was applied according to the size gap between the permanent magnet and the polished sample (tested gaps: 0.5, 1.0, mm). The MR polishing process was performed at 15 rps in the presence of a m field with an intensity ranging from 460 kA/m to 384 kA/m (verified by a teslameter net-Physik, FH 51, Dr. Steingroever, Germany) with a Hall probe) for 5 min. ...
... Subsequently, the initial depth of the cut and the surface roughness were measured. In the next step, the sample was fixed in the MR device and a given volume (0.12-0.36 mL) of an MR slurry (which was sonicated before use to ensure better dispersion properties [39]) was applied according to the size of the gap between the permanent magnet and the polished sample (tested gaps: 0.5, 1.0, and 1.5 mm). The MR polishing process was performed at 15 rps in the presence of a magnetic field with an intensity ranging from 460 kA/m to 384 kA/m (verified by a teslameter (Magnet-Physik, FH 51, Dr. Steingroever, Germany) with a Hall probe) for 5 min. ...
A sedimentation-stable magnetorheological (MR) polishing slurry on the basis of ferrofluid, iron particles, Al2O3, and clay nanofiller in the form of sepiolite intended for MR polishing has been designed, prepared, and its polishing efficiency verified. Added clay substantially improved sedimentation stability of the slurry, decreasing its sedimentation rate to a quarter of its original value (1.8 to 0.45 mg s−1) while otherwise maintaining its good abrasive properties. The magnetisation curve measurement proved that designed slurry is soft magnetic material with no hysteresis, and its further suitability for MR polishing was confirmed by its magnetorheology namely in the quadratically increased yield stress due to the effect of applied magnetic field (0 to 600 kA m−1). The efficiency of the MR polishing process was tested on the flat samples of injection-moulded polyamide and verified by surface roughness/3D texture measurement. The resulting new composition of the MR polishing slurry exhibits a long-term stable system with a wide application window in the MR polishing process.
... Ultrasonic dispersion technology uses its own physical and chemical effect in a liquid to disperse solid particles. As a certain intensity of ultrasonic wave passes through the liquid, the cavitation effect will occur (Guo et al., 2021). The dispersion of ultrasonic wave is mainly dependent on the liquid cavitation, which refers to the growth and collapse dynamic processes of micro cavitation bubbles in a liquid when the sound waves pressure reaches a certain level. ...
It is well known that in the flotation of copper-nickel sulfide ore, pentlandite and serpentine are easy to form hetero-aggregation, which makes it difficult to separate them. Therefore, dispersion operation is indispensable, including chemical and physical dispersion. Chemical dispersion is usually achieved by adding dispersing reagents, which is widely used in mineral flotation, while the study of ultrasonic dispersion in copper-nickel sulfide ores in physical dispersion is less reported. Thus ultrasonic dispersion technology was introduced to weaken the hetero-aggregation and to improve the floatability of pentlandite. Through the implementation of a series of conditional tests of influence factors including ultrasonic site, ultrasonic probe type, ultrasonic time, and ultrasonic power, the optimum ultrasonic dispersion system was demined, and the results showed that the ultrasonic power was the key factor affecting the dispersion of pentlandite-serpentine. Then the dispersion mechanism of ultrasonic was revealed by means of supernatant turbidity measurements, particle-size distribution (PSD) analyses, scanning electron microscopy (SEM), and atomic force microscope (AFM) in succession. Coupled with supernatant turbidity measurements, PSD analyses and SEM images of flotation concentrates all confirmed that the ultra-fine serpentine particles coating on the coarse pentlandite particles were effectively dispersed. AFM analyses depicted the morphological changes of surface roughness treated by different ultrasonic power, and confirmed that the ultrasonic power of 200 W could increase the surface roughness and floatability of pentlandite but decrease that of serpentine. Thus, the difference in floatability between the two minerals were enlarged so as to achieve efficient separation of the two minerals. The results of this research are helpful to understand clearly the mechanism of ultrasonic dispersion of pentlandite-serpentine, which provides an alternative dispersion technology and exhibits great potential for further study and application.
... Cavitating flows are widespread in nature and have numerous engineering applications. The phenomenon of cavitation in liquids has been adapted for aiding industrial processes such as homogenization (Guo et al., 2021), machining (Guo and Zhu, 2018), metrology (Saint-Michel and Garbin, 2020;Bruning et al., 2021), surface cleaning (Song et al., 2004;Chahine et al., 2016), and biomedical procedures of lithotripsy (Bailey et al., 2003) and drug delivery (Stride and Coussios, 2019). On the other hand, detrimental effects of cavitation abound in the form of noise, vibration, material erosion and drop in hydrodynamic efficiency (Carlton, 2018;Kerr et al., 1940;Brennen, 2013;Arndt et al., 2015). ...
In this paper, we numerically investigate the influence of unsteady partial cavitation on the fluid–structure interaction of a freely vibrating hydrofoil section at high Reynolds numbers. We consider an elastically-mounted NACA66 hydrofoil section that is free to vibrate in the transverse flow direction. The fluid–structure interaction of this system is of interest in characterizing the cavitation-induced vibration and noise of marine propellers. The coupled cavitation dynamics and the fluid–structure system are solved using a body-fitted variational framework based on homogeneous mixture-based cavitation with a hybrid URANS-LES turbulence modeling. Specifically, we explore the occurrence of large-amplitude vibrations during unsteady partial cavitating conditions that are absent in the non-cavitating flow configuration. We examine a frequency lock-in phenomenon as the main source of sustained large-amplitude vibration whereby the unsteady lift force locks into a sub-harmonic of the hydrofoil’s natural frequency. We determine the origin of this flow unsteadiness in the vicinity of the trailing edge of the hydrofoil through the interplay between the growing cavity and the adverse pressure gradient. We systematically analyze the impact of flow-induced structural vibration on the combined vortex and cavity synchronization.
... Chen et al. developed a new type of porous lipid drug-loaded PLGA MBs, which increased the drug loading of PLGA nanoparticles, while the addition of DSPC components improved the elasticity of the shell (Chen et al., 2019). This new type of porous lipid drug-loaded PLGA MBs could oscillate under the action of low-frequency US with certain parameters, that is, the "cavitation effect," which could increase the permeability of cell membrane and improve the efficiency of drug action (De Alwis et al., 2021;Guo et al., 2021). We chose this new type of porous lipid drug-loaded PLGA MBs as carriers to prepare lipid CQ/PLGA MBs containing CQ, which improved the shortcomings of low bioavailability, poor water solubility, and cytotoxicity of CQ (Khan et al., 2020;Lv et al., 2021). ...
In recent years, studies have shown a close relationship between cardiomyocyte death and ferroptosis. Clioquinol (CQ) can inhibit ferroptosis. Porous lipid-poly (lactic-co-glycolic acid) (PLGA) microbubbles (MBs) were prepared by double emulsification (W1/O/W2) using 1,2-dioctadecanoyl-sn-glycero-3-phophocholine and PLGA as raw materials. Porous lipid-PLGA MBs were used as carriers to prepare CQ/PLGA MBs containing CQ. CQ/PLGA had the advantages of high drug loading, good biocompatibility, and sustained release. Our results showed that CQ/PLGA improved the effect of CQ and reduced its cytotoxicity. Under low-frequency ultrasound with certain parameters, CQ/PLGA showed steady-state cavitation, which increased the membrane permeability of mouse cardiomyocyte HL-1 to a certain extent and further prevented the process of ferroptosis in mouse cardiomyocyte HL-1.
... In terms of MRP theory, studied MRP on the basis of the reciprocating MRP principle and the Preston equation, and they established the material removal rate model of reciprocating MRP and its normal polishing pressure model. Guo et al. (2021) studied the continuity equation and Vand viscosity equation of suspension, and they established and calculated the modified cavitation bubble dynamics model, which provided a theoretical basis for exploring the ultrasonic cavitation effect of magnetorheological fluid in industrial applications. Chen et al. (2017) established the material removal function model of the MRP process on the basis of the three-dimensional hydrodynamic analysis of MRP and the Preston equation. ...
This work presents the design of a pressurised three-point eccentric magnetorheological polishing (MRP) device, for alumina ceramics' hard and brittle characteristics, and a carrier disc magnetic field generator and a single closed-loop uniform magnetic field generator for a
more uniform and increased magnetic field distribution. When compared with the traditional gap type, this device considerably enhances polishing efficiency. This apparatus has also been used to explore the mechanism of MRP. Static magnetic field simulations were conducted, and the fundamentals of the three-point eccentric magnetorheological process were addressed. Alumina ceramics were polished with a three-point eccentric wheel MRP equipment. Polishing tests were conducted to explore the effects of rotational speed, working pressure, abrasive type, abrasive particle size and polishing duration on polishing properties, and optimised polishing parameters were established. The surface roughness (Ra) of the samples was
dramatically reduced from 500 to 22.41 nm using the three-point eccentric MRP device. The pit markings on the alumina ceramics' surface vanished after polishing. Therefore, the approach has considerable polishing potential for hard and brittle materials that can be nanofabricated with minimal surface sub-damage.
... The decolorization of black sulfuric acid in the US/O 3 system was carried out at different reaction temperatures (20,30,40,50, 60, and 70 • C) for a specific time and for different times (0.5, 1, 1.5, 2, 2.5, 3, 3.5, and 4 h) at a specific temperature under an acid volume of 3 L, ozone flow rate of 1.8 L/h, ultrasonic power density of 200 W⋅L − 1 , and stirring rate of 800 RPM. Fig. 7 shows the effect of the reaction temperature on decolorization efficiency. ...
... However, in the concentrated sulfuric acid system with low water content (<2 wt %), very few hydroxyl radicals are formed from water cavitation bubbles [48]. In addition, cavitation is difficult to achieve in highly viscous liquids using the US alone process [49,50]. Therefore, US alone has a poor degradation effect on organic pollutants in concentrated sulfuric acid with low water content and high viscosity. ...
In this work, a combination of ozone (O3) and ultrasound (US) has been firstly used to decolorize black concentrated sulfuric acid with high organic content. The effect of different reaction factors on the transparency, extent of decolorization, H2SO4 mass fraction, and organic pollutants removal is studied. In addition, the systematic interaction between ultrasound and ozone on the decolorization process is reviewed through comparative experiments of O3, US and US/O3. A sulfuric acid product that meets the requirements for first-class products in national standards, with an extent of decolorization of 74.07%, transparency of 70 mm, and a mass fraction of 98.04%, is obtained under the optimized conditions. Under the same conditions, it has been established that the treatment time can be saved by 25% using the US/O3 process compared to using O3. Further, the production of oxidative free radicals (•OH) in a concentrated sulfuric acid system is enhanced using the US/O3 process compared with O3. In addition, the degree of effectiveness of different oxidizing components on the decolorization process is revealed by adding different free radical shielding agents when the US/O3 process is used.
... In order to achieve the purpose of efficient and green recycling of lithium iron phosphate and aluminum foil, this study aims to study the mechanism and technical process of separating lithium iron phosphate from aluminum foil by ultrasonic method. As ultrasonic separation is a dynamic cavitation process [30,31], the combination of high-speed photographic observation and fluent simulation is used to reveal the detachment mechanism of lithium iron phosphate cathode material and find out the influencing factors of the separation. ...
With the widespread use of lithium iron phosphate batteries in various industries, the amount of waste lithium iron phosphate batteries is also increasing year by year, and if not disposed of in a timely manner, will pollute the environment and waste a lot of metal resources. In the composition of lithium iron phosphate batteries, the cathode has an abundance of elements. The ultrasonic method is a crucial method to recover waste LiFePO4 batteries. It has the following disadvantages, such as the lack of empirical parameters and suitable research equipment. In order to overcome the inefficiency of the LiFePO4 recycling method, the airborne bubble dynamical mechanism of ultrasound in the removal of lithium phosphate cathode material was studied by a high-speed photographic observation and Fluent simulation and the disengagement process. Mainly aimed at the parameters such as action time, power, frequency, and action position in the detachment process were optimized. The recovery efficiency of lithium iron phosphate reached 77.7%, and the recovered lithium iron phosphate powder has good electrochemical properties, with the first charge–discharge ratio of up to 145 (mAh)/g. It is shown that the new disengagement process established in this study was adopted for the recovery of waste LiFePO4.
