The Modeling of Flow Concentration in Two-Phase Materials

1976 ◽  
Vol 98 (2) ◽  
pp. 180-189 ◽  
Author(s):  
T. S. Cook ◽  
C. A. Rau ◽  
E. Smith
Keyword(s):  
Development Program ◽  
High Strength ◽  
Theoretical Models ◽  
Operating Conditions ◽  
Micromechanical Modeling ◽  
High Yield ◽  
Experimental Investigations ◽  
Two Phase ◽  
Wide Range ◽  
Materials Research

Many high strength alloys that are developed for arduous operating conditions have essentially a two-phase microstructure that is produced by a precipitation-hardening procedure. However, alloys that are heat-treated to have maximum hardness, often have poor monotonic and poor fatigue fracture characteristics when these are assessed in relation to their high yield strengths, and this imposes limits to their use for service applications. Experimental investigations covering a wide range of precipitation-hardened alloys have shown that the inferior fracture properties are due to plastic deformation being concentrated within narrow zones. Against this background, Pratt & Whitney Aircraft is undertaking a comprehensive theoretical investigation based on the representation of flow concentration by appropriate theoretical models. The general objective is to provide a quantitative understanding of flow concentration, both with respect to its causes and consequences, in terms of both material and externally imposed parameters such as, for example, the state of loading. The aim of the present paper is not to survey the complete problem of flow concentration in the light of the research undertaken to date, but to provide a limited number of examples that illustrate how specific aspects of the problem have been considered using appropriate models to describe the operative physical processes. With the Conference’s objectives in mind, the paper’s general intention is therefore to provide further evidence that micromechanical modeling can be successfully used to relate mechanical behavior with metallurgical parameters, and thereby add further support for the view that such work forms an integral part of any balanced materials research and development program.

scholarly journals Current Advances in Ejector Modeling, Experimentation and Applications for Refrigeration and Heat Pumps. Part 2: Two-Phase Ejectors

Inventions ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 16 ◽  
Author(s):  
Zine Aidoun ◽  
Khaled Ameur ◽  
Mehdi Falsafioon ◽  
Messaoud Badache
Keyword(s):  
Heat Pumps ◽  
Operating Conditions ◽  
Industrial Processes ◽  
Experimental Investigations ◽  
Mixing Enhancement ◽  
Data Generation ◽  
Two Phase ◽  
Wide Range ◽  
Potential Applications ◽  
And Performance

Two-phase ejectors play a major role as refrigerant expansion devices in vapor compression systems and can find potential applications in many other industrial processes. As a result, they have become a focus of attention for the last few decades from the scientific community, not only for the expansion work recovery in a wide range of refrigeration and heat pump cycles but also in industrial processes as entrainment and mixing enhancement agents. This review provides relevant findings and trends, characterizing the design, operation and performance of the two-phase ejector as a component. Effects of geometry, operating conditions and the main developments in terms of theoretical and experimental approaches, rating methods and applications are discussed in detail. Ejector expansion refrigeration cycles (EERC) as well as the related theoretical and experimental research are reported. New and other relevant cycle combinations proposed in the recent literature are organized under theoretical and experimental headings by refrigerant types and/or by chronology whenever appropriate and systematically commented. This review brings out the fact that theoretical ejector and cycle studies outnumber experimental investigations and data generation. More emerging numerical studies of two-phase ejectors are a positive step, which has to be further supported by more validation work.

Experimental Investigations of Pressure Drop in the Combustion Chamber of Gas Turbine

1989 ◽  
Author(s):  
Marek Dzida ◽  
Krzysztof Kosowski
Keyword(s):  
Pressure Drop ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Relative Pressure ◽  
Wide Range ◽  
Few Data

In bibliography we can find many methods of determining pressure drop in the combustion chambers of gas turbines, but there is only very few data of experimental results. This article presents the experimental investigations of pressure drop in the combustion chamber over a wide range of part-load performances (from minimal power up to take-off power). Our research was carried out on an aircraft gas turbine of small output. The experimental results have proved that relative pressure drop changes with respect to fuel flow over the whole range of operating conditions. The results were then compared with theoretical methods.

Experimental Validation and Design Simulations of a Passive Two-Phase Cooling System for Datacenters

2020 ◽  
Author(s):  
Jackson B. Marcinichen ◽  
John R. Thome ◽  
Raffaele L. Amalfi ◽  
Filippo Cataldo
Keyword(s):  
Thermal Performance ◽  
Experimental Validation ◽  
Cooling System ◽  
Electronics Cooling ◽  
Operating Conditions ◽  
Two Phase ◽  
Data Set ◽  
Pressure Drops ◽  
Wide Range ◽  
Important Challenge

Abstract Thermosyphon cooling systems represent the future of datacenter cooling, and electronics cooling in general, as they provide high thermal performance, reliability and energy efficiency, as well as capture the heat at high temperatures suitable for many heat reuse applications. On the other hand, the design of passive two-phase thermosyphons is extremely challenging because of the complex physics involved in the boiling and condensation processes; in particular, the most important challenge is to accurately predict the flow rate in the thermosyphon and thus the thermal performance. This paper presents an experimental validation to assess the predictive capabilities of JJ Cooling Innovation’s thermosyphon simulator against one independent data set that includes a wide range of operating conditions and system sizes, i.e. thermosyphon data for server-level cooling gathered at Nokia Bell Labs. Comparison between test data and simulated results show good agreement, confirming that the simulator accurately predicts heat transfer performance and pressure drops in each individual component of a thermosyphon cooling system (cold plate, riser, evaporator, downcomer (with no fitting parameters), and eventually a liquid accumulator) coupled with operational characteristics and flow regimes. In addition, the simulator is able to design a single loop thermosyphon (e.g. for cooling a single server’s processor), as shown in this study, but also able to model more complex cooling architectures, where many thermosyphons at server-level and rack-level have to operate in parallel (e.g. for cooling an entire server rack). This task will be performed as future work.

Numerical Modelling and Development of New Technical Solutions in Metallurgy and Material Processing

2020 ◽  
Vol 304 ◽  
pp. 113-119
Author(s):  
Alexander Pesin ◽  
Puneet Tandon ◽  
Denis Pustovoytov ◽  
Alexey Korchunov ◽  
Ilya Pesin ◽  
...  
Keyword(s):  
New York ◽  
High Strength ◽  
Theoretical Models ◽  
Experimental Investigations ◽  
Asymmetrical Rolling ◽  
Steel Making ◽  
Plate Rolling ◽  
Rapid Changes ◽  
Almost All ◽  
Technical Solutions

There have been no breakthroughs in ferrous metallurgy for the last 80 years. Automation and digitalization arrived, while the actual steel making processes saw almost no changes. Today, almost all industries experience rapid changes. In 2018 we will see a launch of trains that can travel as fast as1,200 km/h. In 2022 we will see aircrafts capable of flying from London to New York in 1 hour. They already know how to grow human arms and legs. And driverless taxis have become extremely popular. Should we be expecting to see a major breakthrough in metallurgy any time soon? In this paper you will learn about this and other problems, as well as possible ways to solve them. Also, the paper focuses on the results of the development of theory, mathematical models and novel processes, which were helpful in the forming of the ultra-high strength materials by combining the conventional methods of forming such as stamping, plate rolling, plastic bending and asymmetrical rolling. The ultimate aim was to manufacture parts having complex geometries of ultra-high strength sheets. Metalworking techniques like asymmetrical rolling gave rise to very high shear strains and it was used for increasing the strength of the materials. The addition of the incremental sheet forming to the varied combinations of conventional forming processes was used for increasing in the flexibility of the manufacturing process for ultra-high strength. The results of the research project were also encompassing numerical simulation and experimental investigations of the combined process accompanied by the development of the theoretical models for the same.

Process Development of Silicon-Silicon Carbide Hybrid Micro-Engine Structures

2001 ◽  
Vol 687 ◽  
Author(s):  
Dongwon Choi ◽  
Robert J. Shinavski ◽  
Wayne S. Steffier ◽  
Skip Hoyt ◽  
S.Mark Spearing
Keyword(s):  
Silicon Carbide ◽  
Residual Stresses ◽  
Elevated Temperatures ◽  
Process Development ◽  
High Stress ◽  
Development Program ◽  
High Strength ◽  
Operating Conditions ◽  
Source Power ◽  
Silicon Silicon

AbstractA MEMS-based gas turbine engine is being developed for use as a button-sized portable power generator or micro-aircraft propulsion source. Power densities expected for the micro- engine require high combustor exit temperatures (1300-1700K) and very high rotor peripheral speeds (300-600m/s). These harsh operating conditions induce high stress levels in the engine structure, and thus require refractory materials with high strength. Silicon carbide has been chosen as the most promising material for use in the near future due to its high strength and chemical inertness at elevated temperatures. However, techniques for microfabricating single- crystal silicon carbide to the level of high precision needed for the micro-engine are not currently available. To circumvent this limitation and to take advantage of the well-established precise silicon microfabrication technologies, silicon-silicon carbide (SiC) hybrid turbine structures are being developed using chemical vapor deposition of poly-SiC on silicon wafers and wafer bonding processes. Residual stress control of SiC coatings is of critical importance to all the silicon-silicon carbide hybrid structure fabrication steps since a high level of residual stresses causes wafer cracking during the planarization, as well as excessive wafer bow, which is detrimental to the subsequent planarization and bonding processes. The origins of the residual stresses in CVD SiC layers have been studied. SiC layers (as thick as 30µm) with low residual stresses (on the order of several tens of MPa) have been produced by controlling CVD process parameters such as temperature and gas ratio. Wafer-level SiC planarization has been accomplished by mechanical polishing using diamond grit and bonding processes are currently under development using interlayer materials such as silicon dioxide or poly-silicon. These process development efforts will be reviewed in the context of the overall micro-engine development program.

scholarly journals Numerical and Experimental Investigation of Formability in Incremental Sheet Forming of Particle Reinforced Metal Matrix Composite Sheets

2021 ◽  
Author(s):  
Shakir Gatea ◽  
Thana Abdel Salam Tawfiq ◽  
Hengan Ou
Keyword(s):  
Metal Matrix ◽  
Room Temperature ◽  
Single Point ◽  
Weight Ratio ◽  
High Strength ◽  
Operating Conditions ◽  
Particle Composite ◽  
Heat Treated ◽  
Wide Range ◽  
Sic Particle

Abstract Metal matrix composites (MMCs) have a high strength-to-weight ratio, high stiffness, and good damage resistance under a wide range of operating conditions, making them a viable alternative to traditional materials in a variety of technical applications. Because of their high strength, composite materials are hard to deform to a significant depth at room temperature. As a result, additional treatments are required to enhance the composite's room ductility prior to deformation. In this investigation, as-received 6092Al/SiCp composite sheets (T6-condition) are heat treated to O-condition annealing to enhance its ductility in order to assess the influence of single point incremental forming (SPIF) parameters on the formability and fracture behavior of the Al/SiC particle composite sheets at room temperature. Then the annealed sheets are heat treated to T6-condition to enhance the strength and achieve properties equivalent to as-received sheets properties. The results demonstrate that the Al/SiC particle composite sheets with T6 treatment could not be deformed to the specified depth at room temperature due to low room ductility and that further treatment, such as O-condition annealing, is required to enhance the room ductility. When annealed Al/SiCp composite sheets are heat treated to T6, the sheets exhibit properties comparable to the as-received sheets. Al/SiC particle composite sheets with low SPIF parameters may have greater formability and fracture depth with low strain hardening curve.

scholarly journals Program for determination of zones of gold concentration on sluices of washing devices

2021 ◽  
Vol 895 (1) ◽  
pp. 012002
Author(s):  
V S Alekseev ◽  
R S Seryi
Keyword(s):  
High Performance ◽  
Two Phase Flow ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Phase Flow ◽  
Technological Parameters ◽  
Two Phase ◽  
Alluvial Gold ◽  
Wide Range ◽  
Host Rocks

Abstract Currently sluice washing devices are the most common in alluvial gold mining. Their use provides a sufficiently high performance, relatively low power consumption, and acceptable recovery of valuable components. The theoretical provisions of traditional hydraulics make it possible to determine all the main parameters of the movement of particles of rocks and gold in the pulp, however, in real operating conditions of the sluice box, their actual values will differ greatly from the calculated ones, especially if there are solid fractions in the pulp with a particle size of more than 20 mm. This is explained by significant fluctuations in the values of the surface, average and bottom velocities of the two-phase flow, vertical pulsation velocity in conditions of constrained movement of the different fractional composition of rocks. The article presents the results of experimental studies to identify the dependence of the distance traveled by an individual gold particle and host rocks in a two-phase flow through a sluice, the bottom of which is lined with trapping coatings, on the design and technological parameters of the flushing device. The mathematical model for determining this distance formed the basis of the Gold Enriching program. The program allows, in a wide range of initial data, to determine the zones of concentration of gold of a certain size at the sluice boxes.

scholarly journals Temperature Compensation for Conductivity-Based Phase Fraction Measurements with Wire-Mesh Sensors in Gas-Liquid Flows of Dilute Aqueous Solutions

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7114
Author(s):  
Philipp Wiedemann ◽  
Felipe de Assis Dias ◽  
Eckhard Schleicher ◽  
Uwe Hampel
Keyword(s):  
Temperature Effects ◽  
Temperature Compensation ◽  
Phase Distribution ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Wire Mesh ◽  
Effect Of Temperature ◽  
Experimental Investigations ◽  
Fluid Temperature ◽  
Two Phase

Wire-mesh sensors are well-established scientific instruments for measuring the spatio-temporal phase distribution of two-phase flows based on different electrical conductivities of the phases. Presently, these instruments are also applied in industrial processes and need to cope with dynamic operating conditions increasingly. However, since the quantification of phase fractions is achieved by normalizing signals with respect to a separately recorded reference measurement, the results are sensitive to temperature differences in any application. Therefore, the present study aims at proposing a method to compensate temperature effects in the data processing procedure. Firstly, a general approach is theoretically derived from the underlying measurement principle and compensation procedures for the electrical conductivity from literature models. Additionally, a novel semi-empirical model is developed on the basis of electrochemical fundamentals. Experimental investigations are performed using a single-phase water loop with adjustable fluid temperature in order to verify the theoretical approach for wire-mesh sensor applications and to compare the different compensation models by means of real data. Finally, the preferred model is used to demonstrate the effect of temperature compensation with selected sets of experimental two-phase data from a previous study. The results are discussed in detail and show that temperature effects need to be handled carefully—not merely in industrial applications, but particularly in laboratory experiments.

Machine Learning-Based Model for Optimal Operating Conditions of Thermosyphons for Electronic Cooling Applications

2021 ◽  
Author(s):  
John Kim ◽  
Raffaele L. Amalfi
Keyword(s):  
Machine Learning ◽  
Thermal Performance ◽  
Cooling System ◽  
Electronic Cooling ◽  
Operating Conditions ◽  
Complex Nature ◽  
System Control ◽  
Optimal Operating ◽  
Two Phase ◽  
Wide Range

Abstract Two-phase cooling systems based on the thermosyphon operating principle exhibit excellent heat transfer performance, reliability, and flexibility, therefore can be applied to overcome thermal challenges in a wide range of electronic cooling applications and deployment scenarios. However, extremely complex nature of two-phase flow physics involving flow patterns and phase transitions has been the major challenge for technology adoption in industry. This paper demonstrates a machine learning (ML) based model for evaluating the thermal performance and refrigerant mass flow rate, of a thermosyphon cooling system for telecom equipment. Unlike conventional laboratory approach that requires numerous sensors attached to a cooling system to capture their thermal performance, the new model requires a minimum number of sensors to monitor the health of a thermal management solution. Using the proposed model, a system control module can be further developed which could identify optimal operating parameters in real-time under dynamically changing heat load conditions and actively maintain safety and thermal requirements.

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