An improved sonication method for removal of microorganisms from surfaces
Improved ultrasonic cavitation methods for removing microorganisms from stainless steel strip surfaces
MICROORGANISM↗
SEARCH · Engineering Papers
Results for “CAVITATION”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Analysis of single- and two-phase flows in turbopump inducers.
Single-phase and two-phase cavitating flow regime performance of liquid propellant rocket engine turbopump inducers
SINGLE-PHASE FLOW↗
Analysis of single- and two-phase flows in turbopump inducers.
Single-phase and two-phase cavitating flow regime performance of liquid propellant rocket engine turbopump inducers
INDUCER↗
Characterization of irradiated AISI 316L stainless steel disks removed from the Spallation Neutron Source
Irradiated AISI 316L stainless steel disks were removed from the Spallation Neutron Source (SNS) for post-irradiation examination (PIE) to assess mechanical property changes due to radiation damage and erosion of the target vessel. Topics reviewed include high-resolution photography of the disk specimens, cleaning to remove mercury (Hg) residue and surface oxides, profile mapping of cavitation pits using high frequency ultrasonic testing (UT), high-resolution surface replication, and machining of test specimens using wire electrical discharge machining (EDM), tensile testing, Rockwell Superficial hardness testing, Vickers microhardness testing, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The effectiveness of the cleaning procedure was evident in the pre- and post-cleaning photography and permitted accurate placement of the test specimens on the disks. Due to the limited amount of material available and the unique geometry of the disks, machine fixturing and test specimen design were critical aspects of this work. Multiple designs were considered and refined during mock-up test runs on unirradiated disks. The techniques used to successfully machine and test the various specimens will be presented along with a summary of important findings from the laboratory examinations.
cavitation-induced erosion↗
Complex-Concentrated Anion Doping Enables Ultra-Stable Lattice Oxygen and Structural Integrity in Lithium-Rich Layered Oxide Cathodes
Lithium- and manganese-rich layered oxides (LMR) stand out as next-generation lithium-ion cathode chemistries, which harness both transition-metal and lattice-oxygen redox processes to deliver exceptional capacity and energy density. However, their full potential is hindered by intrinsic oxygen instability and structural degradation, resulting in pronounced voltage fade and capacity decay. Here, we present a complex-concentrated anion-doping paradigm in which multiple anions, F, Br, and S, are incorporated into the oxygen sublattice to enhance oxygen-redox and structural stability. X-ray absorption spectroscopy and aberration-corrected scanning transmission electron microscopy confirm ultra-stable local oxygen coordination environments during long-term cycling, with detrimental phase transformations and oxygen-loss-induced cavitation dramatically inhibited. Notably, we show that the characteristic LiTM6 transition metal (TM) honeycomb ordering is preserved even after electrochemical cycling. Concurrently, this strategy yields an unprecedented volume change of only 0.63% upon charging to 4.8 V vs. Li+/Li, achieving the first zero-strain LMR cathode. The resulting LMR cathode delivers ultralow voltage fade (1 mV per cycle during the first 100 cycles and becomes negligible in subsequent cycles) and outstanding energy retention (93% after 200 cycles) in a pouch cell configuration. Our complex-concentrated anion-doping concept establishes a broadly applicable strategy for resolving chemo-mechanical failure mechanisms in ceramic intercalation electrodes for next-generation energy storage.
Li-ion batteries↗
Entropy‐Maximized Synthesis of Multimetallic Nanoparticle Catalysts via a Ultrasonication‐Assisted Wet Chemistry Method under Ambient Conditions
Abstract A facile ultrasonication‐assisted wet chemistry method for preparing multicomponent alloy nanoparticles (NPs) including high‐entropy alloys (HEAs) is reported. PtAuPdRhRu alloy (HEA), quaternary PtAuPdRh alloy, and ternary PtAuPd alloy NPs are produced with ≈3 nm in diameter. Taking advantage of the acoustic cavitation phenomenon in ultrasonication process, noble metal precursors could be co‐reduced by chemical reductants and transform to alloy structures under operation at room conditions. The instantaneous massive energy (≈5000 °C, 2000 atm) occurring in momentary timespans (≤10 −9 s) contributes to the formation of multimetallic mixed nanomaterials driven by entropy maximization. Owing to strong synergistic effects, the catalysts with the HEA NPs supported on carbons exhibit prominent electrocatalytic activities for hydrogen evolution reaction.
Liu, Miaomiao↗
Optimization of leaf morphology in relation to leaf water status: A theory
The leaf economic traits such as leaf area, maximum carbon assimilation rate, and venation are all correlated and related to water availability. Furthermore, leaves are often broad and large in humid areas and narrower in arid/semiarid and hot and cold areas. We use optimization theory to explain these patterns. We have created a constrained optimization leaf model linking leaf shape to vein structure that is integrated into coupled transpiration and carbon assimilation processes. The model maximizes net leaf carbon gain (NPPleaf) over the loss of xylem water potential. Modeled relations between leaf traits are consistent with empirically observed patterns. As the results of the leaf shape-venation relation, our model further predicts that a broadleaf has overall higher NPPleaf compared to a narrowleaf. In addition, a broadleaf has a lower stomatal resistance compared to a narrowleaf under the same level of constraint. With the same leaf area, a broadleaf will have, on average, larger conduits and lower total leaf xylem resistance and thus be more efficient in water transportation but less resistant to cavitation. By linking venation structure to leaf shape and using water potential as the constraint, our model provides a physical explanation for the general pattern of the covariance of leaf traits through the safety-efficiency trade-off of leaf hydraulic design.
59 BASIC BIOLOGICAL SCIENCES↗
Hydrodynamic trait coordination and cost–benefit trade‐offs throughout the isohydric–anisohydric continuum in trees
Abstract Whole‐plant hydraulic performance depends on the integrated function of trait complexes, such as embolism resistance, stomatal closure mechanisms, and root properties. The diversity of such traits produces a wide range of response strategies to both short‐term variation of environmental conditions and long‐term changes to climate and hydrological cycles. This study aims to assess the role of different emergent hydraulic trait combinations in trees' vulnerability to drought using a quantitative modelling framework. This modelling framework may be helpful in studying the influence of plant hydraulic traits independently. It will also be used to assess how different groups of traits interact to form viable hydraulic strategies in response to different environmental conditions. We use the advanced plant hydrodynamic model, finite‐difference ecosystem‐scale tree crown hydrodynamics model version 2, to resolve plant functional traits of roots, stems, and leaves and simulate the transpiration. We define a multidimensional hydraulic “strategy space” by considering a continuum of these traits to test the outcomes of different hypothetical strategies in response to environmental conditions as observed in Northern Michigan, USA. We evaluate the degree to which simulated trees suffer hydraulic failure due to cavitation or carbon deficiency in response to reduced stomatal conductance. Our results demonstrate how the relationship between plant hydraulic strategy and hydraulic safety margin emerges from trait combinations along different tissue levels. Our findings suggest that hydrodynamic models present an exciting new possibility to define and study plant traits and hydrodynamics.
Mirfenderesgi, Golnazalsadat↗
A higher‐order unsplit 2D direct Eulerian finite volume method for two‐material compressible flows based on the MOOD paradigms
SUMMARY A higher‐order unsplit multi‐dimensional discretization of the diffuse interface model for two‐material compressible flows proposed by R. Saurel, F. Petitpas and R. A. Berry in 2009 is developed. The proposed higher‐order method is based on the concepts of the Multidimensional Optimal Order Detection (MOOD) method introduced in three recent papers for single‐material flows. The first‐order unsplit multi‐dimensional Finite Volume discretization presented by SPB serves as foundation for the development of the higher‐order unlimited schemes. Specific detection criteria along with a novel decrementing algorithm for the MOOD method are designed in order to deal with the complexity of multi‐material flows. Numerically, we compare errors and computational times on several 1D problems (stringent shock tube and cavitation problems) computed on 2D meshes with the second‐ and fourth‐order MOOD methods using a classical MUSCL method as reference. Several simulations of a 2D shocked R22 bubble in the air are also presented on Cartesian and unstructured meshes with the second‐ and fourth‐order MOOD methods, and qualitative comparisons confirm the conclusions obtained with 1D problems. These numerical results demonstrate the robustness of the MOOD approach and the interest of using more than second‐order methods even for locally singular solutions of complex physics models. Copyright © 2014 John Wiley & Sons, Ltd.
Diot, S.↗
Improving the reliability of machine learned potentials for modeling inhomogeneous liquids
The atomic-scale response of inhomogeneous fluids at interfaces and surrounding solute particles plays a critical role in governing chemical, electrochemical, and biological processes. Classical molecular dynamics simulations have been applied extensively to simulate the response of fluids to inhomogeneities directly, but are limited by the accuracy of the underlying interatomic potentials. Here, we use neural network potentials (NNPs) trained to ab initio simulations to accurately predict the inhomogeneous responses of two distinct fluids: liquid water and molten NaCl. Although NNPs can be readily trained to model complex bulk systems across a range of state points, we show that to appropriately model a fluid's response at an interface, relevant inhomogeneous configurations must be included in the training data. In order to sufficiently sample appropriate configurations of such inhomogeneous fluids, we develop protocols based on molecular dynamics simulations in the presence of external potentials. We demonstrate that NNPs trained on inhomogeneous fluid configurations can more accurately predict several key properties of fluids—including the density response, surface tension and size-dependent cavitation free energies—for liquid water and molten NaCl, compared to both empirical interatomic potentials and NNPs that are not trained on such inhomogeneous configurations. This work therefore provides a first demonstration and framework to extract the response of inhomogeneous fluids from first principles for classical density-functional treatment of fluids free from empirical potentials.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
A fish-eye view of riverine hydropower systems. Understanding the biological response to turbine passage
One-way connectivity maintained by fish passing through hydropower turbines in fragmented rivers can be important to population dynamics, but can introduce a new and significant source of mortality due to turbine-associated mortality. Sources of mortality during downstream turbine passage can come from several sources including blade strike, shear forces, cavitation, or pressure decreases, and parsing the contributions of these individual forces is important for advancing and deploying turbines that minimize these impacts to fishes. We used a national hydropower database and conducted a systematic review of the literature to accomplish three goals: (1) report on the spatial distribution of turbine types and generation capacities in the USA, (2) determine fish mortality rates among turbine types and fish species and (3) examine relationships between physical forces similar to those encountered during fish turbine passage and fish injury and mortality. We found that while Francis turbines generate 56% of all US hydropower and have the highest associated fish mortality of any turbine type, these turbines are proportionally understudied compared to less-common and less injury-associated Kaplan turbines, particularly in the Pacific Northwest. While juvenile salmonid species in actual or simulated Kaplan turbine conditions were the most commonly studied, the highest mortality rates were reported in percid fishes passing through Francis turbines. Also, although there are several mechanisms of turbine-associated injury, barotrauma was the most commonly studied with swim bladder rupture, exopthalmia, eye gas bubbles, and prolapsed cloaca being the most serious symptoms associated with rapid pressure decreases. Future studies should focus on understanding which species are most at-risk to turbine passage mortality and, subsequently, increasing the diversity of taxonomy and turbine types in evaluations of turbine mortality.
13 HYDRO ENERGY↗
Temperature effects on adsorption and capillarity water retention mechanisms in constrained unsaturated soils
Abstract This paper focuses on the impact of elevated temperatures on the adsorptive and capillarity water retention mechanisms of unsaturated soils under constrained (constant volume) conditions. This topic is critical for simulating the thermo-hydraulic behavior of soils in hydrogeological or geotechnical applications, including climate change effects on near surface soils, energy piles or soil borehole thermal energy storage systems in unsaturated soil layers, and buffers for geological nuclear waste repositories. A nonisothermal soil water retention curve (SWRC) that separately considers the temperature-dependency of the key parameters governing adsorptive and capillarity water retention mechanisms and soil physical parameters (e.g., surface tension, contact angle, adsorption capacity, cation exchange capacity, mean cavitation suction, air entry value and equilibrium film thickness) was developed to provide insights into the impact of temperature on water retention over the full suction range. The nonisothermal SWRC was validated using experimental data on high plasticity clays, with a good prediction of temperature effects on adsorption and capillarity water retention mechanisms in constrained unsaturated soils.
Lu, Yu↗
Heterogeneous Creep Deformations and Correlation to Microstructures in Fe-30Cr-3Al Alloys Strengthened by an Fe 2 Nb Laves Phase
We have develooped a new Fe-Cr-Al (FCA) alloy system with good oxidation resistance and creep strength at high temperature. The alloy system is a candidate for use in future fossil-fueled power plants. The creep strength of these alloys at 973 K (700 °C) was found to be comparable with traditional 9 pct Cr ferritic–martensitic steels. A few FCA alloys with general composition of Fe-30Cr-3Al-.2Si-xNb (x = 0, 1, or 2) with a ferrite matrix and Fe 2 Nb-type Laves precipitates were prepared. The detailed microstructural characterization of samples, before and after creep rupture testing, indicated precipitation of the Laves phase within the matrix, Laves phase at the grain boundaries, and a 0.5 to 1.5 μm wide precipitate-free zone (PFZ) parallel to all the grain boundaries. In these alloys, the areal fraction of grain boundary Laves phase and the width of the PFZ controlled the cavitation nucleation and eventual grain boundary ductile failure. Finally, we used a phenomenological model to compare the creep strain rates controlled by the effects of the particles on the dislocations within the grain and at grain boundaries. (The research sponsored by US-DOE, Office of Fossil Energy, the Crosscutting Research Program).
36 MATERIALS SCIENCE↗
Solidification Behavior of Calcium Ferrite Under Ultrasonic Vibration
Ultrasonic vibration was applied to the solidification process of calcium ferrite (CF) to modify the grain size and improve the homogeneity of the solidified microstructure. The effects of ultrasound on microstructure, density, compressive strength, and reducibility were studied. The acoustic pressure decreased and then increased along the axis symmetry due to the attenuation of acoustic pressure and reflection of ultrasonic waves in the melt under a fixed power. When the ultrasonic power was increased, the general acoustic pressure increased, which was beneficial to the avoidance of macropores and to improvement of the microstructure. Coarse acicular CF grains were significantly refined; the grain size decreased from 1967 to 442 μm when the ultrasonic power was increased from 0 to 300 W. The density of the samples increased from 4370 to 4680 kg/m{sup 3} due to cavitation and acoustic streaming effects. Ultrasonic vibration greatly improved the ultimate compressive strength of CF; the values were 41.8 ± 2.1 to 67.3 ± 3.4 MPa for ultrasonic powers of 100 to 300 W, respectively. Without ultrasonic treatment, it was only 37.4 ± 1.9 MPa. Ultrasonic vibration also influenced the reduction time of CF due to the composition segregation in the slag during solidification.
36 MATERIALS SCIENCE↗
Effect of Applied Stress and Temperature on Residual Stresses Induced by Peening Surface Treatments in Alloy 600
In this study, the effects of applied tensile stress and temperature on laser shock peening (LSP) and cavitation shotless peening (CSP)-induced compressive residual stresses were investigated using neutron and x-ray diffraction. Residual stresses on the surface, measured in situ, were lower than the applied stress in LSP- and CSP-treated Alloy 600 samples (2 mm thick). The residual stress averaged over the volume was similar to the applied stress. Compressive residual stresses on the surface and balancing tensile stresses in the interior relax differently due to hardening induced by LSP. Ex situ residual stress measurements, using XRD, show that residual stresses relaxed as the applied stress exceeded the yield strength of the LSP- and CSP-treated Alloy 600. Compressive residual stresses induced by CSP and LSP decreased by 15-25% in magnitude, respectively, on exposure to 250-450 °C for more than 500 h with 10-11% of relaxation occurring in the first few hours. Further, 80% of the compressive residual stresses induced by LSP and CSP treatments in Alloy 600 were retained even after long-term aging at 350 °C for 2400 h.
36 MATERIALS SCIENCE↗
Mechanical Surface Treatments of AISI 304 Stainless Steel: Effects on Surface Microrelief, Residual Stress, and Microstructure
The surface roughness, residual stress, and microstructure of AISI 304 stainless steel specimens after laser shock peening (LSP), water jet cavitation peening (WjCP), water jet shot peening (WjSP), and multi-pin ultrasonic impact treatment (UIT) were studied in this work. Compared to the initial state, the surface roughness (Ra) was, respectively, decreased by approx. 5.5, 7.8, 38.2, and 91.1% after the LSP, WjCP, WjSP, and UIT processes. The volume fraction of ε-martensite of ~ 3-5% was observed in all treated specimens except for the LSP-treated ones. The volume fraction of α′-martensite was increased in the following sequence: WjCP (~ 5%), LSP (~ 5%), WjSP (~ 25%), UIT (~ 50%). The studied mechanical surface treatments promote a significant reduction in grains size of both austenite (~ 15-20 nm) and martensite (~ 20-37 nm) leading to essential hardening. All studied processes result in the formation of compressive residual stresses (− 377…693 MPa) and the improvement in the bearing curve parameters. The microhardness estimated accounting for the contributions of different hardening mechanisms to the yield strength magnitude correlates well with the experimental data. The grain boundary hardening and dislocation hardening are concluded to be the most influential mechanisms.
36 MATERIALS SCIENCE↗
Creep Deformation and Damage Mechanisms in an Advanced High-Temperature Additively Manufactured Nickel-Base Superalloy
Abstract This research investigates the processing–structure–properties–performance relationship in a novel nickel-base superalloy, ABD ® -900AM, designed for extreme environments. Specifically tailored for additive manufacturing (AM), ABD ® -900AM maintains mechanical integrity at high temperatures and is comparable to other nickel-based superalloys with a 30–40% gamma-prime volume fraction. A comprehensive study was conducted using laser-beam powder bed fusion and electron-beam powder bed fusion methods. Factors such as heat treatment, porosity, build orientation, and hot isostatic pressing were evaluated to understand their effects on microstructure and mechanical performance. Microstructural characterization revealed significant differences in grain size and orientation across build processes and heat treatments. High-temperature mechanical testing indicated that grain size, heat treatment, and orientation significantly influence creep behavior. A super-solvus heat treatment led to recrystallization and grain growth, significantly improving creep properties compared to a near-solvus heat treatment. Various creep mechanisms were identified across different conditions, and creep rupture models were developed for each build process. Post-test microstructural analysis showed grain boundary damage, with differences in creep cavitation morphology under varying stress conditions. It was shown that MC carbides grow at the expense of gamma-prime near grain boundaries, leading to precipitate-free zones in specimens tested at higher temperatures. This study fills a significant gap in fundamental research by offering a deeper insight into the high-temperature mechanical behavior of additively manufactured nickel-base superalloys. It also explores critical research questions regarding the role of carbides and the significance of heat treatment. The insights gained enhance confidence in the industry adoption of ABD ® -900AM and similar alloys for high-temperature applications, bridging the knowledge gap and supporting the development of reliable AM processes for extreme environments.
Bridges, Alex (ORCID:000000030338759X)↗
Multimodal 3D characterization of voids in shock-loaded tantalum: Implications for ductile spallation mechanisms
Predicting the failure of crystalline materials at high strain rates requires knowledge of the underlying failure mechanisms and their dependence on microstructure. However, little experimental consensus exists on the underlying micromechanics of spallation. In this study, a 3D-EBSD characterization experiment is performed on tantalum prior to and after partial spallation by plate impact, which allowed for the statistical assessment of the microstructural neighborhoods surrounding incipient voids. In analyzing the resulting dataset containing 5884 grains and 467 voids, it is observed that the voids were roughly spherical and consistent in size throughout the spalled material. The voids mostly resided at quadruple points, at triple junctions, at grain boundaries, and within grains, in decreasing order of prevalence. Moreover, voids tended to form at grain boundaries with high degrees of plastic incompatibility, growing into the plastically soft grain but orienting primarily with or perpendicular to the loading direction. Here, the statistics from these analyses of 3D microstructural data support dynamic cavitation models for ductile spallation.
36 MATERIALS SCIENCE↗