scholarly journals Metallurgical Modelling of Ti-6Al-4V for Welding Applications

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 960
Author(s):  
Matteo Villa ◽  
Jeffery W. Brooks ◽  
Richard Turner ◽  
Frédéric Boitout ◽  
Robin Mark Ward
Keyword(s):  
Relative Phase ◽  
Welding Process ◽  
High Energy ◽  
Operating Conditions ◽  
High Energy Density ◽  
Fe Model ◽  
Numerical Predictions ◽  
Wide Range ◽  
Experimental Characterisation ◽  
Characterisation Methods

Manufacturing processes such as welding subject the α/β titanium alloy Ti-6Al-4V to a wide range of temperatures and temperature rates, generating microstructure variations in the phases and in the precipitate dimensions. In this study, the metallurgical and numerical modelling of Ti-6Al-4V when subjected to a high energy density welding process was affected by a series of analytical equations coded in Sysweld commercial specialist FE welding software. Numerical predictions were compared with experimental results from laser welding tests on plates with different thicknesses, initial microstructural morphologies, and operating conditions. The evolution of the microstructure was described by using a diffusion-based approach when the material was operating in the α + β field, whilst empirical equations were used for temperatures above the β-transus temperature. Predictions made by the subroutines within the FE model were shown to match with reasonable trends when validated using experimental characterisation methods for various metallurgical features, including the α particle size, β grain size, martensitic needle thickness, and relative phase volume fractions.

Temperature relaxation in strongly-coupled binary ionic mixtures

2021 ◽  
Author(s):  
Robert Sprenkle ◽  
Luciano Silvestri ◽  
M. S. Murillo ◽  
Scott Bergeson
Keyword(s):  
Material Properties ◽  
Inertial Confinement Fusion ◽  
Coulomb Systems ◽  
High Energy ◽  
High Energy Density ◽  
Inertial Confinement ◽  
Relaxation Rates ◽  
Strongly Coupled ◽  
Wide Range ◽  
Temperature Relaxation

Abstract New facilities such as the National Ignition Facility and the Linac Coherent Light Source have pushed the frontiers of high energy-density matter. These facilities offer unprecedented opportunities for exploring extreme states of matter, ranging from cryogenic solid-state systems to hot, dense plasmas, with applications to inertial-confinement fusion and astrophysics. However, significant gaps in our understanding of material properties in these rapidly evolving systems still persist. In particular, non-equilibrium transport properties of strongly-coupled Coulomb systems remain an open question. Here, we study ion-ion temperature relaxation in a binary mixture, exploiting a recently-developed dual-species ultracold neutral plasma. We compare measured relaxation rates with atomistic simulations and a range of popular theories. Our work validates the assumptions and capabilities of the simulations and invalidates theoretical models in this regime. This work illustrates an approach for precision determinations of detailed material properties in Coulomb mixtures across a wide range of conditions.

scholarly journals Metals and Alloys Additives as Enhancer for Rocket Propulsion: A Review

2021 ◽  
Vol 90 (1) ◽  
pp. 1-9
Author(s):  
Izham Izzat Ismail ◽  
Norhuda Hidayah Nordin ◽  
Muhammad Hanafi Azami ◽  
Nur Azam Abdullah
Keyword(s):  
Specific Impulse ◽  
Flame Temperature ◽  
High Energy ◽  
Combustion Efficiency ◽  
High Energy Density ◽  
Regression Rate ◽  
High Entropy ◽  
Rocket Propulsion ◽  
Wide Range ◽  
Metal Additives

A rocket's engine usually uses fuel and oxygen as propellants to increase the rocket's projection during launch. Nowadays, metallic ingredients are commonly used in the rocket’s operation to increase its performance. Metallic ingredients have a high energy density, flame temperature, and regression rate that are important factors in the propulsion process. There is a wide range of additives have been reported so far as catalysts for rocket propulsion. The studies show that the presence of metal additives improves the regression rate, specific impulse and combustion efficiency. Herein, the common energetic additives for rocket propulsion such as metal and light metals are reviewed. Besides the effect of these energetic particles on the regression behaviors of base (hybrid) fuel has been exclusively discussed. This paper also proposed a new alloy namely high entropy alloys (HEAs) as a new energetic additive that can potentially increase the performance of the rocket propellant system.

scholarly journals Nucleation Triggering of Highly Undercooled Xylitol Using an Air Lift Reactor for Seasonal Thermal Energy Storage

2018 ◽  
Author(s):  
Marie DUQUESNE ◽  
Elena PALOMO DEL BARRIO ◽  
Alexandre GODIN
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
High Energy ◽  
Operating Conditions ◽  
High Energy Density ◽  
Bubble Generation ◽  
Spontaneous Nucleation ◽  
Air Lift Reactor ◽  
Air Lift

Xylitol is an organic, non-toxic, biosourced phase change material with high potential for seasonal thermal energy storage material. It has a high energy density, a high and stable undercooling allowing storing solar energy at ambient temperature thus, reducing thermal losses and the risk of spontaneous nucleation (i.e., the risk of losing the stored energy). When the energy is needed, the discharge triggering of the storage system (i.e., Nucleation triggering of highly viscous undercooled Xylitol) is very difficult as well as reaching a sufficient power delivery (i.e., the control of the subsequent crystal growth rates). Both are the mains locks for the use of Xylitol in seasonal energy storage. Different techniques to crystallize highly undercooled Xylitol have hence been considered. It has been proven that nucleation triggering of highly undercooled Xylitol using an air lift reactor would allow reaching performances matching with building applications (i.e., at medium temperatures, below 100 °C). The advantages of this technique compared to other existing techniques to activate the crystallization are discussed. The mechanisms triggering the nucleation are investigated. The air bubble generation, transportation of nucleation sites and subsequent crystallization are discussed to improve the air injection operating conditions.

scholarly journals Electrochemical Performance Improvement of the Catalyst of the Methanol Micro-Fuel Cell Using Carbon Nanotubes

2019 ◽  
Author(s):  
Mohammad Kazemi Nasrabadi ◽  
Amir Ebrahimi-Moghadam ◽  
Mohammad Hosein Ahmadi ◽  
Ravinder Kumar ◽  
Narjes Nabipour
Keyword(s):  
Carbon Nanotubes ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Carbon Black ◽  
Oxidation Reaction ◽  
High Energy ◽  
Proton Exchange ◽  
Operating Conditions ◽  
High Energy Density ◽  
Methanol Oxidation Reaction

Due to low working temperature, high energy density and low pollution, proton exchange fuel cells have been investigated under different operating conditions in different applications. Using platinum catalysts in methanol fuel cells leads to increasing the cost of this kind of fuel cell which is considered as a barrier to the commercialism of this technology. For this reason, a lot of efforts have been made to reduce the loading of the catalyst required on different supports. In this study, carbon black (CB) and carbon nanotubes (CNT) have been used as catalyst supports of the fuel cell as well as using the double-metal combination of platinum-ruthenium (PtRu) as anode electrode catalyst and platinum (Pt) as cathode electrode catalyst. The performance of these two types of electro-catalyst in the oxidation reaction of methanol has been compared based on electrochemical tests. Results showed that the carbon nanotubes increase the performance of the micro-fuel cell by 37% at maximum power density, compared to the carbon black. Based on thee-electrode tests of chronoamperometry and voltammetry, it was found that the oxidation onset potential of methanol for CNT has been around 20% less than CB, leading to the kinetic improvement of the oxidation reaction. The current density of methanol oxidation reaction increased up to 62% in CNT sample compared to CB supported one, therefore the active electrochemical surface area of the catalyst has been increased up to 90% by using CNT compared to CB which shows the significant rise of the electrocatalytic activity in CNT supported catalyst. Moreover, the resistance of the CNT supported sample to poisonous intermediate species has been found 3% more than CB supported one. According to the chronoamperometry test results, it was concluded that the performance and sustainability of the CNT electro-catalyst show remarkable improvement compared to CB electro-catalyst in the long term.

Experimental and Numerical Study for Improved Understanding of Mixed-Convection Type of Flows in Turbine Casing Cavities During Shut-Down Regimes

2021 ◽  
Author(s):  
Oguzhan Murat ◽  
Budimir Rosic ◽  
Koichi Tanimoto ◽  
Ryo Egami
Keyword(s):  
Natural Convection ◽  
Flow Field ◽  
Mixed Convection ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Scale Model ◽  
Unsteady Temperature ◽  
Numerical Predictions ◽  
Wide Range ◽  
Turbine Casing

Abstract Due to increase in the power generation from renewable sources, steam and gas turbines will be required to adapt for more flexible operations with frequent start-ups and shut-downs to provide load levelling capacity. During shut-down regimes, mixed convection takes place with natural convection dominance depending on the operating conditions in turbine cavities. Buoyant flows inside the turbine that are responsible for non-uniform cooling leading to thermal stresses and compromise clearances directly limits the operational flexibility. Computational fluid dynamics (CFD) tools are required to predict the flow field during these regimes since direct measurements are extremely difficult to conduct due to the harsh operating conditions. Natural convection with the presence of cross-flow -mixed convection has not been extensively studied to provide detailed measurements. Since the literature lacks of research on such flows with real engine representative operating conditions for CFD validation, the confidence in numerical predictions is rather inadequate. This paper presents a novel experimental facility that has been designed and commissioned to perform very accurate unsteady temperature and flow field measurements in a simplified turbine casing geometry. The facility is capable of reproducing a wide range of Richardson, Grashof and Reynolds numbers which are representative of engine realistic operating conditions. In addition, high fidelity, wall resolved LES with dynamic Smagorinsky subgrid scale model has been performed. The flow field as well as heat transfer characteristics have been accurately captured with LES. Lastly, inadequacy of RANS for mixed type of flows has been highlighted.

Dielectric Elastomer Energy Harvesting and its Application to Human Walking

2011 ◽  
Author(s):  
Heather Lai ◽  
Chin An Tan ◽  
Yong Xu
Keyword(s):  
Energy Harvesting ◽  
Knee Joint ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
High Energy ◽  
Dielectric Elastomer ◽  
Metabolic Energy ◽  
High Energy Density ◽  
Human Walking ◽  
Wide Range

Human walking requires sophisticated coordination of muscles, tendons, and ligaments working together to provide a constantly changing combination of force, stiffness and damping. In particular, the human knee joint acts as a variable damper, dissipating greater amounts of energy when the knee undergoes large rotational displacements during walking, running or hopping. Typically, this damping results from the dissipation, or loss, of metabolic energy. It has been proven to be possible however; to collect this otherwise wasted energy through the use of electromechanical transducers of several different types which convert mechanical energy to electrical energy. When properly controlled, this type of device not only provides desirable structural damping effects, but the energy generated can be stored for use in a wide range of applications. A novel approach to an energy harvesting knee joint damper is presented using a dielectric elastomer (DE) smart material based electromechanical transducer. Dielectric elastomers are extremely elastic materials with high electrical permittivity which operate based on electrostatic effects. By placing compliant electrodes on either side of a dielectric elastomer film, a specialized capacitor is created, which couples mechanical and electrical energy using induced electrostatic stresses. Dielectric elastomer energy harvesting devices not only have a high energy density, but the material properties are similar to that of human tissue, making it highly suitable for wearable applications. A theoretical framework for dielectric elastomer energy harvesting is presented along with a mapping of the active phases of the energy harvesting to the appropriate phases of the walking stride. Experimental results demonstrating the energy harvesting capability of a DE generator undergoing strains similar to those experienced during walking are provided for the purpose of verifying the theoretical results. The work presented here can be applied to devices for use in rehabilitation of patients with muscular dysfunction and transfemoral prosthesis as well as energy generation for able-bodied wearers.

scholarly journals AWE experimental laser plasma program

2000 ◽  
Vol 18 (2) ◽  
pp. 213-218 ◽  
Author(s):  
M. DUNNE ◽  
J. EDWARDS ◽  
P. GRAHAM ◽  
A. EVANS ◽  
S. ROTHMAN ◽  
...  
Keyword(s):  
Equation Of State ◽  
Inertial Confinement Fusion ◽  
Fusion Energy ◽  
Strong Shock ◽  
High Energy ◽  
High Energy Density ◽  
Radiation Hydrodynamics ◽  
Inertial Confinement ◽  
X Ray ◽  
Wide Range

The achievement of ignition from an Inertial Confinement Fusion capsule will require a detailed understanding of a wide range of high energy density phenomena. This paper presents some recent work aimed at improving our knowledge of the strength and equation of state characteristics of low-Z materials, and outlines data which will provide quantitative benchmarks against which our predictive radiation hydrodynamics capabilities can be tested. Improvements to our understanding in these areas are required if reproducible and predictable fusion energy production is to be achieved on the next generation of laser facilities.In particular, the HELEN laser at AWE has been used to create a thermal X-ray source with 140 eV peak radiation temperature and 3% instantaneous flux uniformity to allow measurements of the Equation of State of materials at pressures up to 20 Mbar to an accuracy of <±2% in shock velocity. The same laser has been used to investigate the onset of spallation upon the release of a strong shock at a metal-vacuum boundary, with dynamic radiography used to image the spalled material in flight for the first time. Finally, a range of experiments have been performed to generate quantitative radiation hydrodynamics data on the evolution of gross target defects, driven in both planar and imploding geometry. X-ray radiography was used to record the evolving target deformation in a system where the X-ray drive and unperturbed target response were sufficiently characterized to permit meaningful analysis. The results have been compared to preshot predictions made using a wide variety of fluid codes, highlighting substantial differences between the various approaches, and indicating significant discrepancies with the experimental reality. The techniques developed to allow quantitative comparisons are allowing the causes of the discrepancies to be identified, and are guiding the development of new simulation techniques.

scholarly journals Nonaqueous redox-flow batteries: organic solvents, supporting electrolytes, and redox pairs

2015 ◽  
Vol 8 (12) ◽  
pp. 3515-3530 ◽  
Author(s):  
Ke Gong ◽  
Qianrong Fang ◽  
Shuang Gu ◽  
Sam Fong Yau Li ◽  
Yushan Yan
Keyword(s):  
Energy Density ◽  
Organic Solvents ◽  
Cell Voltage ◽  
High Energy ◽  
High Energy Density ◽  
Redox Flow Battery ◽  
High Cell ◽  
Redox Flow Batteries ◽  
Working Temperature ◽  
Wide Range

As members of the redox-flow battery (RFB) family, nonaqueous RFBs can offer a wide range of working temperature, high cell voltage, and potentially high energy density.

The Critical Pressure at the Onset of Flame Instability of Syngas/Air/Diluent Outwardly Expanding Flame at Different Initial Temperatures and Pressures

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Ziyu Wang ◽  
Ziwei Bai ◽  
Guangying Yu ◽  
Sai Yelishala ◽  
Hameed Metghalchi
Keyword(s):  
High Speed ◽  
Critical Pressure ◽  
Hydrodynamic Instability ◽  
Experimental Studies ◽  
Initial Pressure ◽  
High Energy ◽  
Oxide Semiconductor ◽  
High Energy Density ◽  
Flame Instability ◽  
Wide Range

Syngas has gained attention recently due to its high energy density and environmentally friendly characteristics. Flame stability plays an important role in flame propagation in energy conversion devices. Experimental studies were performed in a cylindrical chamber to investigate flame instability of syngas/air/diluent mixture. A Z-shape Schlieren system coupled with a high-speed complementary metal–oxide–semiconductor camera was used to record flame pictures up to 40,000 frames per second. In this research, syngas is a mixture of hydrogen and carbon monoxide and diluent is a blend of 14% CO2 and 86% N2 with the same specific heat as the burned gases. Three main flame instabilities namely Rayleigh–Taylor (body force) instability, hydrodynamic instability, and thermal-diffusive instability have been studied. For the onset of flame instability, a power law correlation for the ratio of critical pressure to initial pressure of syngas/air/diluent flames over a wide range of initial temperatures (298–450 K), initial pressures (1.0–2.0 atm), equivalence ratios (0.6–3.0), diluent concentrations (0–10%), and hydrogen percentages (5–25%) in the fuel has been developed.

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