scholarly journals CFD Simulation Based Investigation of Cavitation Dynamics during High Intensity Ultrasonic Treatment of A356

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1529
Author(s):  
Eric Riedel ◽  
Niklas Bergedieck ◽  
Stefan Scharf
Keyword(s):  
Ultrasonic Treatment ◽  
High Intensity ◽  
Aluminium Alloys ◽  
Cfd Simulation ◽  
Numerical Models ◽  
Acoustic Streaming ◽  
Industrial Applications ◽  
Software Environment ◽  
Wide Range ◽  
Semi Solid

Ultrasonic treatment (UST) and its effects, primarily cavitation and acoustic streaming, are useful for a high range of industrial applications, e.g., welding, filtering, cleaning or emulsification. In the metallurgy and foundry industry, UST can be used to modify a material’s microstructure by treating metal in the liquid or semi-solid state. Cavitation (formation, pulsating growth and implosion of tiny bubbles) and its shock waves, released during the implosion of the cavitation bubbles, are able to break forming structures and thus refine them. In this context, especially aluminium alloys are in the focus of the investigations. Aluminium alloys, e.g., A356, have a significantly wide range of industrial applications in automotive, aerospace and machine engineering, and UST is an effective and comparatively clean technology for its treatment. In recent years, the efforts for simulating the complex mechanisms of UST are increasing, and approaches for computing the complex cavitation dynamics below the radiator during high intensity ultrasonic treatment have come up. In this study, the capabilities of the established CFD simulation tool FLOW-3D to simulate the formation and dynamics of acoustic cavitation in aluminium A356 are investigated. The achieved results demonstrate the basic capability of the software to calculate the above-mentioned effects. Thus, the investigated software provides a solid basis for further development and integration of numerical models into an established software environment and could promote the integration of the simulation of UST in industry.

scholarly journals Generation and transportation of high-intensity pulsed ion beam at varying background pressures

2017 ◽  
Vol 35 (4) ◽  
pp. 587-596 ◽  
Author(s):  
X.P. Zhu ◽  
L. Ding ◽  
Q. Zhang ◽  
Yu. Isakova ◽  
Y. Bondarenko ◽  
...  
Keyword(s):  
Energy Density ◽  
High Intensity ◽  
Focal Point ◽  
Ion Beam ◽  
Industrial Applications ◽  
Ion Source ◽  
Beam Deflection ◽  
Appreciable Change ◽  
Energy Density Distribution ◽  
Wide Range

AbstractHigh-intensity pulsed ion beam (HIPIB) technology is developed as an advanced manufacturing method for components with improved wear, corrosion and/or fatigue performance, etc. Robust HIPIB equipment with stable repetitive operation, long-lifetime, and easy maintenance are desired for industrial applications, on which stability of ion beam parameters is critical to achieve consistent result of reproducibility. Here, magnetically insulated ion diodes (MIDs) as ion source with durable graphite anode are investigated in a simple self-magnetic field configuration under repetitive operation. Influence of background pressure on ion beam generation and transportation is emphasized since ion beam sources were intrinsically a vacuum-based system. Comparative experiments were conducted on two types of HIPIB equipment, that is, TEMP-6 and TEMP-4M, differing in vacuum packages where turbo-molecular pump or oil diffusion pump was used. Both the HIPIB equipments are operated on a bipolar pulse mode, that is, a first negative pulse of 150–200 kV with pulse duration 450–500 ns to generate anode plasma on explosive electron emission, and a second positive pulse of 200–250 kV with 120 ns to accelerate the ions. Ion beam energy density up to 8 J/cm2 is achievable using MIDs of geometrical focusing configuration, and the total energy, energy density distribution along cross-section, deflection and divergence, and charge neutralization of the ion beams are assessed under background pressures in a wide range of two orders of magnitude, that is, 1–100 mPa. No appreciable change in the parameters is observed up to 50 mPa, and merely a slight increase in the beam deflection from about ±3 mm to about ±4 mm at the focal point over 50 mPa. The stability of ion beam at the varied pressure is mainly facilitated by the higher pressure up to several Pa in anode–cathode gap during plasma generation and good neutralizing effect for ion beam transportation.

Laser Forming of Metal Foam Sandwich Panels: Effect of Panel Manufacturing Method

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Tizian Bucher ◽  
Min Zhang ◽  
Chang Jun Chen ◽  
Ravi Verma ◽  
Wayne Li ◽  
...  
Keyword(s):  
Metal Foam ◽  
Numerical Models ◽  
Sandwich Panels ◽  
Weight Ratio ◽  
Industrial Applications ◽  
Laser Forming ◽  
Process Conditions ◽  
Foam Core ◽  
Wide Range ◽  
The Impact

Sandwich panels with metal foam cores have a tremendous potential in various industrial applications due to their outstanding strength-to-weight ratio, stiffness, and shock absorption capacity. A recent study paved the road toward a more economical implementation of sandwich panels, by showing that the material can be successfully bent up to large angles using laser forming. The study also developed a fundamental understanding of the underlying bending mechanisms and established accurate numerical models. In this study, these efforts were carried further, and the impact of the foam core structure, the facesheet and foam core compositions, and the adhesion method on the bending efficiency and the bending limit was investigated. These factors were studied individually and collectively by comparing two fundamentally different sandwich panel types. Thermally induced stresses at the facesheet/core interface were thoroughly considered. Numerical modeling was carried out under different levels of geometric accuracy to complement bending experiments under a wide range of process conditions. Interactions between panel properties and process conditions were demonstrated and discussed.

scholarly journals Contactless Ultrasonic Treatment in Direct Chill Casting

JOM ◽  
2020 ◽  
Vol 72 (11) ◽  
pp. 4082-4091
Author(s):  
Catherine E. H. Tonry ◽  
Valdis Bojarevics ◽  
Georgi Djambazov ◽  
Koulis Pericleous
Keyword(s):  
Grain Refinement ◽  
Ultrasonic Treatment ◽  
Numerical Models ◽  
Acoustic Streaming ◽  
Acoustic Resonance ◽  
Resonant Mode ◽  
Direct Chill ◽  
Ferrous Alloy ◽  
Melt Pool ◽  
Dc Casting

Abstract Uniformity of composition and grain refinement are desirable traits in the direct chill (DC) casting of non-ferrous alloy ingots. Ultrasonic treatment is a proven method for achieving grain refinement, with uniformity of composition achieved by additional melt stirring. The immersed sonotrode technique has been employed for this purpose to treat alloys both within the launder prior to DC casting and directly in the sump. In both cases, mixing is weak, relying on buoyancy-driven flow or in the latter case on acoustic streaming. In this work, we consider an alternative electromagnetic technique used directly in the caster, inducing ultrasonic vibrations coupled to strong melt stirring. This ‘contactless sonotrode’ technique relies on a kilohertz-frequency induction coil lowered towards the melt, with the frequency tuned to reach acoustic resonance within the melt pool. The technique developed with a combination of numerical models and physical experiments has been successfully used in batch to refine the microstructure and to degas aluminum in a crucible. In this work, we extend the numerical model, coupling electromagnetics, fluid flow, gas cavitation, heat transfer, and solidification to examine the feasibility of use in the DC process. Simulations show that a consistent resonant mode is obtainable within a vigorously mixed melt pool, with high-pressure regions at the Blake threshold required for cavitation localized to the liquidus temperature. It is assumed that extreme conditions in the mushy zone due to cavitation would promote dendrite fragmentation and coupled with strong stirring, would lead to fine equiaxed grains.

scholarly journals CFD Modeling of Gas–Solid Cyclone Separators at Ambient and Elevated Temperatures

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 228 ◽  
Author(s):  
Mohammadhadi Nakhaei ◽  
Bona Lu ◽  
Yujie Tian ◽  
Wei Wang ◽  
Kim Dam-Johansen ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Cfd Simulation ◽  
Separation Efficiency ◽  
Flow Behavior ◽  
Industrial Applications ◽  
High Mass ◽  
Cfd Modeling ◽  
Solid Flow ◽  
Solids Loading ◽  
Wide Range

Gas–solid cyclone separators are widely utilized in many industrial applications and usually involve complex multi-physics of gas–solid flow and heat transfer. In recent years, there has been a progressive interest in the application of computational fluid dynamics (CFD) to understand the gas–solid flow behavior of cyclones and predict their performance. In this paper, a review of the existing CFD studies of cyclone separators, operating in a wide range of solids loadings and at ambient and elevated temperatures, is presented. In the first part, a brief background on the important performance parameters of cyclones, namely pressure drop and separation efficiency, as well as how they are affected by the solids loading and operating temperature, is described. This is followed by a summary of the existing CFD simulation studies of cyclones at ambient temperature, with an emphasis on the high mass loading of particles, and at elevated temperatures. The capabilities as well as the challenges and limitations of the existing CFD approaches in predicting the performance of cyclones operating in such conditions are evaluated. Finally, an outlook on the prospects of CFD simulation of cyclone separators is provided.

Alloy Design for Semi Solid Metal Forming

2014 ◽  
Vol 783-786 ◽  
pp. 136-141 ◽  
Author(s):  
Gonasagren Govender ◽  
Heinrich Möller ◽  
Ulyate Andries Curle
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Metal Forming ◽  
Aluminium Alloys ◽  
Solid Metal ◽  
Alloy Design ◽  
Processing Temperature ◽  
Wide Range ◽  
Semi Solid ◽  
Alloy Systems

Semi-solid metal forming is more than 40 years old but its full potential to near net shape form high strength aluminium alloys has been realised only to a limited degree. Alloys developed for traditional manufacturing processes were initially used but it became apparent that alloys specific to SSM forming needed to be developed. The main alloy development criteria revolved around SSM processing temperature, solid fraction (fs) versus temperature sensitivity and age hardening potential. This methodology while sound does not fully address the unique processing behaviour of SSM forming. By its very nature SSM requires the controlled solidification of a part of the melt before forming. From basic solidification fundamentals this results in the enrichment of the remaining liquid with alloying elements. During the forming process segregation of liquid phase essentially produces a component with very different compositions in the regions where the liquid solidifies last. From recent work completed on a wide range of standard alloy systems it has become apparent that this segregation effect has a significant impact on aging behaviour and strength. Low melting point structures formed in the these regions result in localised melting in the grain boundary region and along areas of gross liquid segregation during solution heat treatment, contributing to the poor mechanical properties. Although this behaviour can be addressed using modified heat treatment, this cannot be applied to all current alloy systems. Alloy design for SSM forming must take these phenomena into account in order to develop and or specify aluminium alloys with acceptable mechanical properties.

Laser Forming of Metal Foam Sandwich Panels: Effect of Panel Manufacturing Method

2019 ◽  
Author(s):  
Tizian Bucher ◽  
Min Zhang ◽  
Chang Jun Chen ◽  
Ravi Verma ◽  
Wayne Li ◽  
...  
Keyword(s):  
Metal Foam ◽  
Numerical Models ◽  
Sandwich Panels ◽  
Weight Ratio ◽  
Industrial Applications ◽  
Laser Forming ◽  
Process Conditions ◽  
Foam Core ◽  
Wide Range ◽  
The Impact

Abstract Sandwich panels with metal foam cores have a tremendous potential in various industrial applications due to their outstanding strength-to-weight ratio, stiffness, and shock absorption capacity. A recent study paved the road towards a more economical implementation of sandwich panels, by showing that the material can be successfully bent up to large angles using laser forming. The study also developed a fundamental understanding of the underlying bending mechanisms and established accurate numerical models. In this study, these efforts were carried further, and the impact of the foam core structure, the facesheet and foam core compositions, as well as the adhesion method on the bending efficiency and bending limit was investigated. These factors were studied individually and collectively by comparing two fundamentally different sandwich panel types. Thermally-induced stresses at the facesheet/core interface were thoroughly considered. Numerical modeling was carried out under different levels of geometric accuracy, to complement bending experiments under a wide range of process conditions. Interactions between panel properties and process conditions were demonstrated and discussed.

Effect of Ultrasounds during the Solidification Process of the A357 Aluminium Alloy

2012 ◽  
Vol 192-193 ◽  
pp. 428-432
Author(s):  
Antonio Forn ◽  
Manel da Silva ◽  
Maite Teresa Baile ◽  
Josep A. Picas ◽  
Antolí Fauria
Keyword(s):  
Solid State ◽  
Aluminium Alloy ◽  
Ultrasonic Treatment ◽  
Aluminium Alloys ◽  
Solidification Process ◽  
Ultrasonic Waves ◽  
Solid Particles ◽  
Α Phase ◽  
Semi Solid ◽  
Ultrasound Effect

It is known that ultrasonic waves promote nucleation and globulization of solid particles in aluminium alloys. However, the studies performed up to date have been conducted, in the laboratory, using small volumes of aluminium. This article aims to establish the application of ultrasound effect in the A357 aluminium-silicon alloy in amounts of about 2 kg of material. The experiments have been conducted with different parameters of ultrasonic treatment, evaluating the microstructure of the slurry quenched from the semi-solid state. The globulization effect of aluminium α phase by ultrasounds is very effective in the area close to the ultrasonic horn tip and the transmission system, but its effect highly reduces in the regions far away from the source of ultrasonic waves.

Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces

2019 ◽  
Author(s):  
James Ewen ◽  
Carlos Ayestaran Latorre ◽  
Arash Khajeh ◽  
Joshua Moore ◽  
Joseph Remias ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Film Formation ◽  
Substituent Effects ◽  
Vapour Phase ◽  
Industrial Applications ◽  
Phosphate Esters ◽  
Antiwear Additives ◽  
Formation Mechanisms ◽  
Phosphate Ester ◽  
Wide Range

<p>Phosphate esters have a wide range of industrial applications, for example in tribology where they are used as vapour phase lubricants and antiwear additives. To rationally design phosphate esters with improved tribological performance, an atomic-level understanding of their film formation mechanisms is required. One important aspect is the thermal decomposition of phosphate esters on steel surfaces, since this initiates film formation. In this study, ReaxFF molecular dynamics simulations are used to study the thermal decomposition of phosphate esters with different substituents on several ferrous surfaces. On Fe<sub>3</sub>O<sub>4</sub>(001) and α-Fe(110), chemisorption interactions between the phosphate esters and the surfaces occur even at room temperature, and the number of molecule-surface bonds increases as the temperature is increased from 300 to 1000 K. Conversely, on hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>, most of the molecules are physisorbed, even at high temperature. Thermal decomposition rates were much higher on Fe<sub>3</sub>O<sub>4</sub>(001) and particularly α-Fe(110) compared to hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>. This suggests that water passivates ferrous surfaces and inhibits phosphate ester chemisorption, decomposition, and ultimately film formation. On Fe<sub>3</sub>O<sub>4</sub>(001), thermal decomposition proceeds mainly through C-O cleavage (to form surface alkyl and aryl groups) and C-H cleavage (to form surface hydroxyls). The onset temperature for C-O cleavage on Fe<sub>3</sub>O<sub>4</sub>(001) increases in the order: tertiary alkyl < secondary alkyl < primary linear alkyl ≈ primary branched alkyl < aryl. This order is in agreement with experimental observations for the thermal stability of antiwear additives with similar substituents. The results highlight surface and substituent effects on the thermal decomposition of phosphate esters which should be helpful for the design of new molecules with improved performance.</p>

PLATINUM

Alloy Digest ◽  
1970 ◽  
Vol 19 (11) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Heat Treating ◽  
Industrial Applications ◽  
High Melting ◽  
High Melting Point ◽  
White Metal ◽  
Temperature Performance ◽  
Wide Range ◽  
Corrosion And Oxidation

Abstract PLATINUM is a soft, ductile, white metal which can be readily worked either hot or cold. It has a wide range of industrial applications because of its excellent corrosion and oxidation resistance and its high melting point. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Pt-1. Producer or source: Matthey Bishop Inc..

scholarly journals Two-Dimensional Numerical Modeling of Flow in Physical Models of Rock Vane and Bendway Weir Configurations

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 458
Author(s):  
Drew C. Baird ◽  
Benjamin Abban ◽  
S. Michael Scurlock ◽  
Steven B. Abt ◽  
Christopher I. Thornton
Keyword(s):  
Numerical Modeling ◽  
Physical Model ◽  
Numerical Models ◽  
Hydraulic Performance ◽  
Physical Models ◽  
Protection Measures ◽  
Design Engineers ◽  
Model Study ◽  
Study Results ◽  
Wide Range

While there are a wide range of design recommendations for using rock vanes and bendway weirs as streambank protection measures, no comprehensive, standard approach is currently available for design engineers to evaluate their hydraulic performance before construction. This study investigates using 2D numerical modeling as an option for predicting the hydraulic performance of rock vane and bendway weir structure designs for streambank protection. We used the Sedimentation and River Hydraulics (SRH)-2D depth-averaged numerical model to simulate flows around rock vane and bendway weir installations that were previously examined as part of a physical model study and that had water surface elevation and velocity observations. Overall, SRH-2D predicted the same general flow patterns as the physical model, but over- and underpredicted the flow velocity in some areas. These over- and underpredictions could be primarily attributed to the assumption of negligible vertical velocities. Nonetheless, the point differences between the predicted and observed velocities generally ranged from 15 to 25%, with some exceptions. The results showed that 2D numerical models could provide adequate insight into the hydraulic performance of rock vanes and bendway weirs. Accordingly, design guidance and implications of the study results are presented for design engineers.

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