Search Results (632)

Efficient recovery of phenolic compounds from citrus processing by-products requires optimized solvent systems and reliable frameworks for comparing emerging extraction technologies. In this study, a solvent system was first optimized to maximize phenolic recovery from lemon (Citrus limon (L.) Burm. f.) processing by-products, enabling a standardized comparison of ultrasound-assisted extraction (UAE) and hydrodynamic cavitation (HC). A preliminary solid–liquid extraction screening using different water:ethanol ratios (v/v) identified a 50:50 hydroalcoholic mixture as the optimal solvent system for recovering phenolic compounds. HPLC analysis confirmed the presence of major flavanones (eriocitrin and hesperidin) and hydroxycinnamic acids (caffeic, p-coumaric, sinapic, and ferulic acids). Antioxidant capacity was assessed using complementary assays (Folin–Ciocalteu, DPPH, and ORAC) to provide a comprehensive evaluation of antioxidant activity. Under optimized solvent conditions, UAE significantly improved the recovery of total flavanones (+25.9%), hydroxycinnamic acids (+10.3%), total polyphenols (+20.5%), DPPH activity (+6.0%), and ORAC values (+9.6%) compared with conventional extraction. HC further enhanced extraction performance, increasing flavanone recovery by 12.0%, hydroxycinnamic acids by 7.2%, total polyphenols by 5.2%, and antioxidant activity (DPPH and ORAC) by 11.4% and 2.0%, respectively, relative to UAE. Following ethanol removal and concentration, HC-derived extracts showed the highest phenolic content and antioxidant capacity. These results demonstrate that solvent optimization, combined with a standardized comparison of extraction technologies, enhances phenolic recovery from lemon processing by-products. The findings indicate that HC is a promising, scalable approach for the sustainable recovery of bioactive compounds from citrus side-streams. The novelty of this work lies in the integration of solvent optimization with a systematic and standardized comparison of UAE and HC, providing a reproducible framework for evaluating emerging extraction technologies and highlighting the enhanced performance and scalability potential of HC for phenolic recovery from citrus processing by-products. Full article

To improve the lubrication stability of centrifugal pump mechanical seals under high-speed and high-pressure conditions, a composite texture combining elliptical dimples and herringbone grooves is proposed. The Hybrid Groove–Ellipse (HGE) configuration aims to enhance hydrodynamic pressure generation and mitigate thermal accumulation within the sealing interface. A thermohydrodynamic (THD) lubrication model with cavitation was established, and the coupled governing equations were solved using the finite volume method over 600–6000 rpm and 0.1–1 MPa. The lubrication performance of circular, rectangular, and two elliptical textures was systematically evaluated to identify their hydrodynamic characteristics. The ellipse with major axis parallel to the flow direction exhibited the most favorable pressure distribution and load-carrying capacity. Based on this geometry, the HGE structure was developed. Compared with conventional herringbone grooves, the HGE texture increases local pressure buildup, improves the load-carrying-to-leakage ratio, and modifies cavitation distribution. The maximum interface temperature is reduced by approximately 10–20% under high-speed conditions, with improved temperature uniformity. These results demonstrate that geometric coupling can enhance both the hydrodynamic and thermal performance of mechanical seals. Full article

This study analyses the behaviour of brass CB773S with extra-low-lead content in relation to corrosion and the corrosion–cavitation phenomenon. Electrochemical corrosion tests, both potentiodynamic and potentiostatic, as well as corrosion–cavitation tests, were conducted. Various potentials were applied to brass, alongside cavitation generated by an ultrasonic bath. Artificial seawater and artificial brackish water were used as electrolytes. Surface damage was evaluated using a stereo microscope and scanning electron microscopy. The results indicate that the interfaces between alpha and beta phases of brass serve as preferential sites for the nucleation and collapse of vapour bubbles under cavitation conditions, leading to a deep pitting, especially in artificial brackish water under this synergy. Susceptibility to a selective corrosion of the Zn-rich phase was observed, highly dependent on the test solution, as well as on the applied potential during the tests. The corrosion–cavitation synergistic damage was strongly dependent on the electrochemical parameters, particularly the applied potential, which plays a key role under cathodic protection conditions. In general, it can be concluded that low-lead brass behaviour is governed by a complex interaction between applied potential, electrolyte chemistry, microstructure, and mechanical effect. These findings provide valuable insights into brass’s performance under service conditions where corrosion and cavitation may appear simultaneously in marine environments. Full article

Upgrading existing hydropower plants into pump storage using pump-turbines is an economical approach to increasing energy storage capacity. Installing an additional pump at the pump-turbine outlet can improve cavitation performance and reduce submergence requirements. The present work proposes a methodology for designing an axial flow pump for such retrofitting applications. A classical method available in the literature was used for establishing the global parameters and boundary conditions of the pump design. The method was automated using a Python 3.13 script to handle a wide range of design parameters. The design output was verified with five different cases covering a wide operational range, from low to high specific speed axial pumps. The results met the required performance criteria, with deviations in head prediction ranging from 0.28 to 1.70 m for most cases. The estimated maximum error was 20% for the mid-range of specific speeds, and the largest deviations were observed for the extreme design conditions. These deviations under extreme specific speeds can be attributed to the limitation of the underlying empirical correlations, which are primarily developed for a typical axial pump. Therefore, further refinement or robust optimization is necessary for reliable application under such extreme conditions. Overall, the verification clearly demonstrated the potential to produce geometrically consistent and hydraulically reasonable designs. The adapted design approach provides good confidence and will provide baseline designs for the booster pump in retrofitted hydropower plants. Full article

This study numerically investigates the influence of different fluid temperatures on the cavitation characteristics of a space-use micropump under microgravity conditions. A homogeneous multiphase model coupled with a thermal modified Zwart–Gerber–Belamri cavitation model is employed, and the SST turbulence model is applied to resolve the cavitating flow under rated and off-design flow rates. Results indicate that cavitation behavior is strongly dependent on both temperature and flow rate. At low temperatures, cavitation intensity increases, leading to reductions in head and efficiency and a slight increase in shaft power. In contrast, elevated temperatures suppress cavitation development, resulting in milder performance degradation and, in some cases, slight improvements in head and shaft power. Internal flow analysis reveals that lower temperatures promote more extensive vapor fraction distributions and greater flow distortion, while entropy production analysis shows that cavitation contributes limited additional loss overall, though entropy generation rises markedly under combined low temperature and high flow rate conditions. The findings highlight that cavitation effects are more pronounced at low temperatures and are further amplified at higher flow rates, providing insights for the design and reliable operation of space micropumps in on-orbit thermal management systems. Full article

Background: In this study, type B gelatin was extracted from Oreochromis niloticus scales under hydrothermal conditions at 60 °C to evaluate the effect of ultrasound-assisted pretreatment on its structural, physicochemical, thermal, and functional properties. Methods: Gelatin obtained with and without ultrasound pretreatment was systematically characterized through molecular weight analysis, proteomic profiling, size determination, surface morphology, proximate composition, thermal behavior, and gelation-related functional properties in order to assess the influence of the extraction method on gelation performance. Results: Ultrasound pretreatment slightly increased gelatin yield from 1.46 to 1.70%, indicating enhanced collagen solubilization. Proteomic analysis confirmed the predominance of fibrillar collagen proteins in both samples, although differences in protein distribution were observed. Furthermore, weight-average molecular weight analysis revealed a reduction from 212.3 ± 11.8 to 170.9 ± 13.2 kDa in the ultrasound-treated sample, suggesting partial fragmentation of collagen chains induced by cavitation effects. Structural modifications were also reflected in increased porosity and surface changes, contributing to improved colloidal stability. However, these changes significantly affect the functional behavior of the gelatin. Ultrasound-treated sample exhibited limited gel-forming capacity and failed to form stable gels at the evaluated concentration, despite complete dissolution. In contrast, gelatin extracted without ultrasound treatment retained higher-molecular-weight fractions and formed stable gels at both 5 and 10% (w/w). Thermal and spectroscopic analyses suggested that the fundamental collagen structure was preserved in both samples, although differences were observed in thermal degradation behavior. Conclusions: These results highlight the importance of controlling ultrasound-assisted extraction conditions to balance collagen recovery with the preservation of molecular integrity required for gelation, providing insights for the development of sustainable fish-derived biomaterials for pharmaceuticals and biomedical applications. Full article

Rain erosion is a critical issue for the development of wind power generation because it limits the lifetime of wind turbine blades. To clarify the erosion initiation mechanism in wind turbine blades of metallic material, pit formation and erosion initiation on a smooth wet wall of aluminum materials A3003 and annealed A5052 were investigated; water droplets were impinged on the wall using a pulsed-jet tester; and combined theoretical and numerical studies were performed by considering the influence of the water film on the wall. Although the theoretical and numerical impact pressures were much lower than the offset yield strength of the materials, random pit formation and erosion initiation were observed on the target material. To clarify the reason for this, the occurrence of cavitation erosion was investigated based on the numerical pressure distribution of a droplet impacting a wet wall. The numerical results showed that the pressures in the droplet center and water film became lower than the saturated vapor pressure, suggesting the occurrence of cavitation erosion. Furthermore, a similar pit formation and erosion initiation were observed on the wall material in the acoustic cavitation test under the cavitation erosion condition. These results indicate that the pit formation could have been caused by the high impact pressure caused by the micro-jet mechanism that occurs when a droplet impacts the wet wall. This could potentially explain the mechanism of the more severe erosion in the actual wind turbine blade than was expected. Full article

Hydrodynamic cavitation in Venturi devices is strongly influenced by geometry and is increasingly considered as a non-thermal route for process intensification in continuous-flow applications, including water-treatment contexts. However, Venturi design practice still relies largely on incremental modifications of circular throats and on loosely formalized heuristics, which limits reproducibility and systematic comparison. This work presents a reproducible geometry-driven framework for the design of an equal-width Venturi throat under a fixed transverse envelope constraint. Two parameterized configurations are considered: a constant-width Reuleaux-triangle cross section (VRA) and a controlled axial-twist variant (VRAt). A minimal set of geometric design indicators is formulated in terms of throat flow area, wetted perimeter, hydraulic diameter, and geometric near-wall coverage within a prescribed thickness; for VRAt, a dimensionless kinematic factor is additionally introduced to quantify the path-length increase associated with the imposed twist. Under equal-width conditions, the Reuleaux section preserves the wetted perimeter of the circular reference while reducing flow area, whereas the twisted variant preserves the same transverse throat metrics and isolates twist as an explicit geometric design variable. The contribution is methodological: it provides a reproducible framework for early-stage geometric design and comparison of Venturi configurations relevant to hydrodynamic cavitation. It does not, by itself, report experiments, validation, or hydraulic, cavitation, or water-treatment performance predictions. Full article

Chelating agents can extend the operational pH range of iron-based advanced oxidation processes, yet comprehensive studies on chelated Fe-activated persulfate systems for textile dye degradation remain scarce. This study establishes an integrated framework for optimizing Fe(II)/persulfate (PS) systems using chelating ligands and hybrid energy inputs under near-neutral conditions. Among the tested systems, Fe(II)/PS complexed with citric acid (CA) exhibited superior performance, achieving ~91% dye removal within 20 min at pH 6.5 under optimized conditions (1.25 mM Fe(II), 10 mM PS, 0.1 mM CA). Chelation stabilized Fe redox cycling and prevented precipitation, enabling effective catalysis across pH 3–10. Optimal CA/Fe and Fe/PS ratios (0.1:1.25 and 1.25:10) yielded ~96% decolorization and 67.65% TOC removal in 60 min, while excessive chelation reduced activity. Transition metal screening (Mn(II), Zn(II), Cu(II), Co(II), and Ni(II) confirmed Fe(II) as the most effective activator, providing removal efficiencies up to 3.2-fold higher than competing metals. Mixed-dye experiments showed competitive degradation, with >37% color removal after 60 min for ternary dye mixtures. Mineralization reached ~92% TOC reduction after 120 min, indicating deep oxidation beyond chromophore cleavage. Reactive species quenching revealed a mixed oxidation mechanism involving ^•OH radicals and high-valent Fe(IV) species. Hybrid assistance improved mineralization, with UVC increasing TOC removal by 15.6%, while solar irradiation provided moderate enhancement under low-energy input. In contrast, low-power ultrasound (40 kHz, 60 W) delivered only 17.6 W acoustic power to the solution and did not improve performance due to limited cavitation and mixing. This work thus contributes a robust platform for advancing chelated iron-persulfate oxidation systems toward practical, effective treatment of recalcitrant dye-contaminated wastewaters under near-neutral conditions. Full article

Metal additive manufacturing (AM) offers unprecedented opportunities to fabricate complex, lightweight metallic components, yet its practical deployment remains fundamentally constrained by defects arising from rapid melting and solidification. Cyclic thermal transients generate cracks, pores, residual stresses, and lack-of-fusion regions, undermining mechanical performance and reliability. Ultrasonic field-assisted laser-based additive manufacturing (UF-LBAM) has emerged as a powerful approach to manipulate melt pool dynamics and suppress defect formation. Nevertheless, the governing physical mechanisms remain poorly understood, particularly under highly non-equilibrium ultrasonic excitation, where acoustic pressure oscillations, melt convection, cavitation, and solidification are intricately coupled across multiple temporal and spatial scales. Here, we provide a systematic review of X-ray based fundamental studies in UF-LBAM and the diverse applications of machine learning (ML), detailing the literature selection criteria and methodology. We highlight advances spanning synchrotron X-ray revealed physical phenomena, ML-driven real-time monitoring and defect prediction, and pathways toward industrial implementation. Critical challenges persist, including fundamental physics gaps, transferability of ML models across alloy systems, and real-time control limitations. We further identify promising directions for the field, such as physics-informed models, multimodal diagnostics, and closed-loop control, which together promise to unlock the full potential of UF-LBAM for high-performance metal component fabrication. Full article

Hydraulic dynamometer is the key equipment to measure the dynamic performance of high-power gas turbines and steam, with its internal flow characteristics directly influencing measurement accuracy and service life. This paper focuses on the power absorption performance and internal flow characteristics of a hydraulic dynamometer with perforated-disk rotor. A hydraulic test platform is established to measure the power absorption performance of megawatt-level hydraulic dynamometers. When the rotor speed reaches a certain value under the full-water condition, the power absorption of the hydraulic dynamometer reaches its limit. Numerical simulations are applied to study the internal flow characteristics and cavitation evolution features of the perforated-disk-type hydraulic dynamometer. The flow within the outermost rotor pores is the primary factor influencing unsteady flow behaviour, with dynamic–static interference playing a key role in inducing flow excitation. Moreover, cavitation mainly occurs in the flow passages of the end rotor and the outermost flow pores of the middle rotor, where the development and collapse of cavitation bubbles lead to flow instability. As the rotation speed decreases, the power absorption performance significantly decreases under cavitation conditions. These findings provide a theoretical basis for the structural optimization and engineering application of high-power hydraulic dynamometers. Full article

This study investigates the acoustic pressure field in a 20 kHz sonoreactor filled with water. A modular sonoreactor and ultrasonic stack were developed at the Łukasiewicz-ITR laboratory. Modal, harmonic response, and harmonic acoustic analyses were performed using the ANSYS Workbench, considering two reactor heights (800 mm and 550 mm). Experimental tests using aluminium foils were conducted, and the results were compared with FEM simulations. The bulk viscosity of the liquid was found to have a significant impact on the numerical results. The novelty of this work lies in estimating an effective bulk viscosity that enables accurate representation of the pressure field distribution within the tank. This parameter is theoretical and, as defined in this study, accounts for the overall energy losses associated with cavitation rather than representing an intrinsic material property. The proposed simulation approach reduces computational time and cost while maintaining agreement between predicted and experimental pressure fields. Good consistency was achieved when the effective bulk viscosity was set to 1300 Pa·s. The presented methodology may support further development and optimization of sonoreactors. It enables rapid evaluation of various geometries, providing a foundation for prototype development or subsequent detailed analyses. Full article

This study employs CiteSpace 6.3 R1 software to conduct a quantitative analysis of 645 cavitation-related centrifugal pump publications from the Web of Science Core Collection database (2007–2025) using bibliometric methods. The analysis encompasses publication volume statistics, keyword co-occurrence analysis, and keyword clustering. The results indicate that research on centrifugal pump cavitation is currently in a phase of rapid development. The annual number of publications related to centrifugal pump cavitation shows an overall fluctuating upward trend, with Jiangsu University emerging as the leading research institution. The research hotspots include fault diagnosis, impeller design, numerical simulation, and validation, forming four major developmental pathways. Research on cavitation in centrifugal pumps has gradually shifted its focus from numerical simulation to practical engineering issues such as pressure pulsation and cavitation, with hot topics evolving at an accelerated pace. Future efforts must address challenges like cavitation monitoring and high-precision simulation to comprehensively enhance the anti-cavitation performance and operational reliability of centrifugal pumps. Full article

Background/Objectives: The aim of this study was to investigate the longitudinal visual field (VF) and circumpapillary retinal nerve fiber layer thickness (cpRNFLT) changes in open-angle glaucomatous (OAG) participants with unilateral peripapillary intrachoroidal cavitation (PICC) and to identify factors associated with VF progression. Methods: Sixty eyes of 30 OAG patients with unilateral PICC were included in this retrospective longitudinal observational study. Humphrey 24–2 VF testing and optical coherence tomography scanning were performed in all eyes over a period exceeding 5 years. VF progression was assessed using mean deviation (MD) and superior and inferior total deviation (TD) slopes. Structural progression was evaluated using global, superior, and inferior cpRNFLT thinning rates. Longitudinal changes were compared between PICC eyes and their contralateral non-PICC eyes. Factors associated with superior or inferior TD slopes were analyzed using linear mixed-effects models. The following variables were included as explanatory variables: age, sex, intraocular pressure, axial length, Bruch’s membrane opening (BMO) and scleral flange opening (SFO) area, SFO/BMO offset magnitude, disk tilt, disk rotation, baseline superior or inferior TD, baseline corresponding cpRNFLT, and the presence of PICC. Results: MD slope was −0.24 ± 0.35 dB/year in PICC eyes and −0.35 ± 0.53 dB/year in contralateral eyes. There was no significant difference in MD slope, superior and inferior TD slope, or the rate of cpRNFLT thinning (all p > 0.05). In multivariable analysis, the presence of PICC was associated with slower progression in the corresponding superior VF (p = 0.037), whereas greater SFO/BMO offset magnitude was associated with faster progression (p = 0.047). Conclusions: OAG eyes with PICC exhibited modest functional and structural progression over 5 years, comparable to that of contralateral non-PICC eyes. The presence of PICC was associated with slower corresponding superior VF progression, whereas greater myopia-associated structural change was related to faster progression. Our findings characterize the clinical course of eyes with pronounced myopic ONH deformation, highlighting the importance of detailed ONH structural assessment in the management of myopic glaucoma. Full article

The replacement of petroleum-based plastics with sustainable and biodegradable materials remains a critical challenge for food packaging and biomedical applications. Gelatin is an attractive natural biopolymer for film fabrication; however, its inherent brittleness, moisture sensitivity, and limited structural stability restrict practical use. In this work, for the first time, low-power direct-probe ultrasonication is introduced as a green and additive-free strategy to regulate molecular organization and enhance the performance of gelatin–glycerol composite films. Systematic variation in ultrasonic power and treatment duration revealed a strong dependence of film structure and properties on processing conditions. Low-power ultrasonication (20 W) promoted gelatin–glycerol interactions, induced a transition from loosely organized molecular arrangements to helix-like molecular packing at the nanometer scale, and produced smooth, compact microscale surface morphologies. As a result, these films exhibited enhanced hydrophilicity, reduced surface defects, and improved thermal stability. In contrast, high-power ultrasonication generated excessive cavitation, leading to large-scale porous structures and diminished thermal and surface performance. Therefore, this work identifies a distinct low-power ultrasonic window that enables controlled molecular reorganization and hierarchical structure formation in gelatin–glycerol systems. Structural and physicochemical analyses using SEM, FTIR, XRD, water contact angle measurements, and thermogravimetric analysis collectively elucidate the ultrasound-driven structure–property relationships within the gelatin–glycerol matrix. Overall, this study demonstrates that controlled ultrasonication enables precise tuning of gelatin-based film architecture and properties, offering a scalable and environmentally friendly route to high-performance biodegradable materials for sustainable packaging and biomedical applications. Full article