The cavitation erosion of ultrasonic sonotrode during large-scale metallic casting: Experiment and simulation

In this work, the static and dynamic compaction response of a six-material mixture, containing both brittle and ductile constituents, is compared. Quasi-static and dynamic compaction experiments were conducted on samples and the results compared to simulations. Optical analyses of compacted samples indicate that dynamically compacting samples to near 300 m/s is not sufficient for complete compaction or localized grain melt. Simulations indicate that a wide distribution of temperature and stress states are achieved in the dynamically compacted samples; compaction speeds should be increased to near 800 m/s at which point copper grains achieve melt temperatures on their surfaces. The experimental data is used to fit a bulk P-α equation of state (EOS) that can be used for simulating large-scale dynamic compaction for industrial applications.

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Prediction of Cavitation Erosion Intensity Using Large-Scale Diesel Nozzles

10.4271/2019-01-2278 ◽

2019 ◽

Author(s):

Motoya Kambara ◽

Takanobu Aochi ◽

Fumiaki Arikawa ◽

Toshiaki Hijima ◽

Kazufumi Serizawa

Keyword(s):

Large Scale ◽

Cavitation Erosion ◽

Erosion Intensity

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Assessment of Cavitation Erosion With a URANS Method

Journal of Fluids Engineering ◽

10.1115/1.4026195 ◽

2014 ◽

Vol 136 (4) ◽

Cited By ~ 23

Author(s):

Zi-ru Li ◽

Mathieu Pourquie ◽

Tom van Terwisga

Keyword(s):

Large Scale ◽

Cavitation Erosion ◽

Time Derivative ◽

Mean Value ◽

Navier Stokes ◽

Local Pressure ◽

Erosion Risk ◽

Damage Area ◽

Large Scale Structures ◽

Unsteady Rans

An assessment of the cavitation erosion risk by using a contemporary unsteady Reynolds-averaged Navier–Stokes (URANS) method in conjunction with a newly developed postprocessing procedure is made for an NACA0015 hydrofoil and an NACA0018-45 hydrofoil, without the necessity to compute the details of the actual collapses. This procedure is developed from detailed investigations on the flow over a hydrofoil. It is observed that the large-scale structures and typical unsteady dynamics predicted by the URANS method with the modified shear stress transport (SST) k-ω turbulence model are in fair agreement with the experimental observations. An erosion intensity function for the assessment of the risk of cavitation erosion on the surface of hydrofoils by using unsteady RANS simulations as input is proposed, based on the mean value of the time derivative of the local pressure that exceeds a certain threshold. A good correlation is found between the locations with a computed high erosion risk and the damage area observed from paint tests.

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Scalable ultrasonic casting of large-scale 2219AA Al alloys: Experiment and simulation

Materials Today Communications ◽

10.1016/j.mtcomm.2021.102329 ◽

2021 ◽

Vol 27 ◽

pp. 102329

Author(s):

Li Zhang ◽

Xiaoqian Li ◽

Zhilin Liu ◽

Ruiqing Li ◽

Ripeng Jiang ◽

...

Keyword(s):

Large Scale ◽

Al Alloys ◽

Experiment And Simulation

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Experimental Study of Mechanism of Silt Abrasion Influenced by Cavitation in Hydraulic Machinery

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1, Symposia – Parts A, B, C, and D ◽

10.1115/ajk2011-06040 ◽

2011 ◽

Author(s):

Tao Zhang ◽

CiChang Chen ◽

Dan Li ◽

DongLi Lv

Keyword(s):

Abrasive Wear ◽

Large Scale ◽

Cavitation Erosion ◽

Large Angle ◽

Solid Particles ◽

Bubble Collapse ◽

Small Scale ◽

Front Part ◽

Trailing Edge ◽

Experimental Conditions

Experiments of cavitation erosion, silt abrasion and their synergetic erosion on Al hydrofoils were made in a testing-section. The erosion depth on hydrofoils was measured, and results showed that the depth value increased gradually with the condition changed from silt abrasion to synergetic erosion (lie due to contemporary action of silt abrasion and cavitation bubble collapse) and meanwhile with the position changed form the front part to the trailing edge of hydrofoil. The microtopography on hydrofoils was observed under the three experimental conditions. The cavitation erosion results appeared as regular-shape pits which differed only in the number per unit area at different position. The silt abrasion patterns was uniform in characteristics around one fixed point on hydrofoil. From the front part to the trailing edge of hydrofoil, the main abrasive wear patterns changed from ploughing type to wedge type. Small scale ploughing or cutting type and large scale wedge type were the main erosion patterns of the synergetic erosion directly caused by solid particles. From the front part to the trailing edge of hydrofoil, the size of small and large scale abrasive wear patterns increased gradually. Combining the analysis and processing of cavitation structure with the silt abrasion and synergetic erosion patterns, a viewpoint about silt abrasion influenced by cavitation was put forward. During the stage of growth of attached cavity, the hydrofoil was eroded by solid particles at small angle as a result of solid particles subjected to cavitation nucleation being accelerated along the surface of hydrofoil, and the erosion patterns were dominated by ploughing or cutting type. During the stage of cavitation cloud collapse in main flow, the hydrofoil was eroded by impact abrasion of solid particles at large angle resulted from solid particles being accelerated to high velocity by micro-jet or pressure wave, and the dominating erosion pattern was wedge type.

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Effects of the variable valve lift difference on in-cylinder gas flow in a four-valve gasoline engine

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1177/0954407018789321 ◽

2018 ◽

Vol 233 (7) ◽

pp. 1806-1817 ◽

Cited By ~ 1

Author(s):

Shiqiang Zhang ◽

Chunshu Li ◽

Ruilin Liu ◽

Jingyang Bao ◽

Miao Chi

Keyword(s):

Phase Difference ◽

Large Scale ◽

Gas Flow ◽

Gasoline Engine ◽

Research Work ◽

Valve Lift ◽

Adjustment Mechanism ◽

Experiment And Simulation ◽

Variable Valve Lift ◽

Variable Valve

The in-cylinder gas flow is an important factor that affects the engine performance. The appropriate swirl can reduce cycle-to-cycle variations, increase flame propagation speed, and improve the combustion efficiency. Many technologies can induce significant swirl, but lead to intake flow loss. In this research work, the variable valve lift difference adjustment mechanism is developed to obtain and adjust in-cylinder swirl without weakening flow capacity in a four-valve gasoline engine. The in-cylinder swirl and tumble characteristics generated by the variable valve lift difference adjustment mechanism are studied by means of experiment and simulation. The results of the experiment and simulation show the intensity of tumble and swirl under the larger lift valve is increased with the increase in the phase difference between two intake cams at same camshaft angle, and a large-scale swirl is formed in the cylinder when the camshaft angles change from 40° to 80°, and another large scale swirl is formed during the camshaft angles change from 100° to 140°, but the rotating direction of the secondary swirl is inverse to that of first swirl. The scale and shape of the in-cylinder tumble and swirl are not changed significantly with the increase in the phase difference between two intake cams when the camshaft angles change from 80° to 100°. A brief discussion on the research results that improve the performance of actual gasoline engine is given.

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Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

International Astronomical Union Colloquium ◽

10.1017/s0252921100031493 ◽

1999 ◽

Vol 173 ◽

pp. 243-248

Author(s):

D. Kubáček ◽

A. Galád ◽

A. Pravda

Keyword(s):

Image Processing ◽

Large Scale ◽

Harvard College ◽

Oak Ridge ◽

Large Scale Structures ◽

Short Period Comet ◽

Short Period ◽

Scale Structures ◽

Harvard College Observatory ◽

Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

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Evolution of Large-Scale Coronal Structures

International Astronomical Union Colloquium ◽

10.1017/s0252921100024945 ◽

1994 ◽

Vol 144 ◽

pp. 29-33

Author(s):

P. Ambrož

Keyword(s):

Magnetic Field ◽

Field Line ◽

Large Scale ◽

Coronal Magnetic Field ◽

Source Surface ◽

Solar Cycles ◽

Characteristic Relationship ◽

The Magnetic Field ◽

Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

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Large-scale Motion of Solar Filaments

International Astronomical Union Colloquium ◽

10.1017/s0252921100064502 ◽

2000 ◽

Vol 179 ◽

pp. 205-208

Author(s):

Pavel Ambrož ◽

Alfred Schroll

Keyword(s):

Magnetic Flux ◽

Proper Motion ◽

Time Scale ◽

Large Scale ◽

Accuracy Of Measurements ◽

Solar Filaments ◽

General Movement ◽

Scale Motion ◽

Velocity Scatter

AbstractPrecise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.

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Some applications of electron beam microanalysis techniques in VLSI process evaluation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007463x ◽

1983 ◽

Vol 41 ◽

pp. 160-161

Author(s):

Simon Thomas

Keyword(s):

Integrated Circuits ◽

Process Evaluation ◽

Large Scale ◽

Technology Development ◽

Analytical Techniques ◽

Successful Implementation ◽

Analysis Of Failures ◽

Characterization Of Materials ◽

Circuits Vlsi

Trends in the technology development of very large scale integrated circuits (VLSI) have been in the direction of higher density of components with smaller dimensions. The scaling down of device dimensions has been not only laterally but also in depth. Such efforts in miniaturization bring with them new developments in materials and processing. Successful implementation of these efforts is, to a large extent, dependent on the proper understanding of the material properties, process technologies and reliability issues, through adequate analytical studies. The analytical instrumentation technology has, fortunately, kept pace with the basic requirements of devices with lateral dimensions in the micron/ submicron range and depths of the order of nonometers. Often, newer analytical techniques have emerged or the more conventional techniques have been adapted to meet the more stringent requirements. As such, a variety of analytical techniques are available today to aid an analyst in the efforts of VLSI process evaluation. Generally such analytical efforts are divided into the characterization of materials, evaluation of processing steps and the analysis of failures.

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