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Author: Hany Kirols
Publisher:
ISBN:
Category :
Languages : en
Pages : 128
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Book Description
Water Droplet Erosion (WDE) is defined as the progressive loss of original material from a solid surface due to continuous impingements of water droplets or jets. In this work, parameters affecting this wear phenomenon are discussed in detail through a literature review. The initial surface roughness as a parameter that may influence WDE process was not given attention in the literature. Therefore, its effect on erosion was studied experimentally. It was concluded that the initial surface roughness has a significant effect on the length of the incubation stage, and may influence the maximum erosion rate. Another point tackled in this work is the WDE results representation. The traditional method of representing erosion results is through a plot between material loss and time. However, this plot neglects important information about the WDE experiment, for instance, the amount of water which has impacted the sample during the test. Therefore, in this work a new representation method of WDE test results was proposed. This new method represents WDE test results with respect to the applied kinetic energy per unit area. WDE erosion result for tests done on 12% Cr stainless steel were successfully represented and analyzed using this method. Finally, the WDE found on ex-service steam turbine blades was studied. The progression of erosion on the surface of the blades was illustrated by the aid of SEM micrographs. This work confirmed that the formation of asperities and depressions are considered the main reasons for pit initiation. In addition, it was also confirmed that the twist angle of the turbine blade around its diagonal, is an important parameter that influences its WDE. Twist angle has an effect on: (a) impact angle, (b) erosion appearance, (c) impact speed, (d) affected area. Furthermore, according to the current experimental results, multi-ray rig erosion tests considered the closest simulation to the actual ex-service blade in terms of damage appearance.
Author: Hany Kirols
Publisher:
ISBN:
Category :
Languages : en
Pages : 128
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Book Description
Water Droplet Erosion (WDE) is defined as the progressive loss of original material from a solid surface due to continuous impingements of water droplets or jets. In this work, parameters affecting this wear phenomenon are discussed in detail through a literature review. The initial surface roughness as a parameter that may influence WDE process was not given attention in the literature. Therefore, its effect on erosion was studied experimentally. It was concluded that the initial surface roughness has a significant effect on the length of the incubation stage, and may influence the maximum erosion rate. Another point tackled in this work is the WDE results representation. The traditional method of representing erosion results is through a plot between material loss and time. However, this plot neglects important information about the WDE experiment, for instance, the amount of water which has impacted the sample during the test. Therefore, in this work a new representation method of WDE test results was proposed. This new method represents WDE test results with respect to the applied kinetic energy per unit area. WDE erosion result for tests done on 12% Cr stainless steel were successfully represented and analyzed using this method. Finally, the WDE found on ex-service steam turbine blades was studied. The progression of erosion on the surface of the blades was illustrated by the aid of SEM micrographs. This work confirmed that the formation of asperities and depressions are considered the main reasons for pit initiation. In addition, it was also confirmed that the twist angle of the turbine blade around its diagonal, is an important parameter that influences its WDE. Twist angle has an effect on: (a) impact angle, (b) erosion appearance, (c) impact speed, (d) affected area. Furthermore, according to the current experimental results, multi-ray rig erosion tests considered the closest simulation to the actual ex-service blade in terms of damage appearance.
Author: Niloofar Kamkar Zahmatkesh
Publisher:
ISBN:
Category :
Languages : en
Pages : 148
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Book Description
Author: Ming Jing
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: Mohammad Sadegh Mahdipoor
Publisher:
ISBN:
Category :
Languages : en
Pages : 178
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Book Description
Water Droplet Erosion (WDE) is a mechanical degradation which is of great concern to power generation and aerospace industries, where water droplets interact with high-speed moving components. It is observed on multiple components of airplanes when flying in the rain, on steam turbine blades, and gas turbine compressor blades which is the focus of this study. Compressor blades in gas turbines suffer from WDE due to the recently implemented technology Inlet Fog Cooling. It is utilized to boost gas turbine efficiency in high ambient temperatures via the spraying of micro-sized water droplets into the intake air. Evaporation of water droplets cools the intake charge and increases the air density. The main drawback of inlet cooling is that part of the water droplets are carried into the compressor by intake air flow, which is called overspray. Repetitive impact between rotating blades and water droplets leads to WDE damage, which is a major problem. This study attempted to improve WDE resistance of compressor blades made of Ti6Al4V. Two different approaches were considered: Studying WDE of TiAl alloy as a potential erosion resistant material for turbine blades and Surface engineering of Ti6Al4V via gas nitriding and HVOF spraying of WC-Co. To investigate WDE in this work, erosion experiments were carried out using the state-of-art WDE rig available at Thermodynamics of Materials Group (TMG), Concordia University. It enables control of erosion conditions such as impact velocity, impact angle, droplet size, and droplet impingement number. In the first stage of this study, WDE of nearly fully lamellar TiAl alloy was directly compared to Ti6Al4V at relatively wide ranges of impact speed (i.e. 275m/s, 300m/s, 325m/s and 350m/s) and droplet size (i.e. 464æm and 603æm). TiAl demonstrated superior erosion performance (i.e. longer incubation period and slower material loss) compared with Ti6Al4V at all tested conditions. Herein, the relation of impact velocity and maximum erosion rates for TiAl and Ti6Al4V alloys was established and the damage threshold speeds of TiAl were determined. Afterwards, the erosion behaviour of TiAl was related to its mechanical properties and irregular microstructure. Lastly, in-depth investigation was carried out to reveal erosion damage mechanism of TiAl at different stages including incubation, material loss initiation, maximum erosion rate, and advanced stages. In the second stage of this study, the influence of gas nitriding on water droplet erosion behaviour of Ti6Al4V was investigated. Ti6Al4V coupons were nitrided at two different temperatures (i.e. 900 and 1050°C) for 5 and 10 hours and the nitrided coupons were characterized. Their erosion behaviour in comparison with as-received and annealed Ti6Al4V was examined at two impact speeds (i.e. 300m/s and 350m/s). Mechanical properties, erosion performance and damage mechanism of treated Ti6Al4V were significantly influenced by the nitriding temperature. Exploring the potential of HVOF spray WC-Co coating to combat WDE was the last part of this study. Erosion performance of two WC-Co coatings was examined at 250m/s, 300m/s and 350m/s impact speeds in comparison with Ti6Al4V. The as-sprayed coating did not show notable WDE protection; however, removing its top layers and smoothing its surface notably improved the erosion performance.
Author: Tadashi Tanuma
Publisher: Woodhead Publishing
ISBN: 0081003250
Category : Technology & Engineering
Languages : en
Pages : 569
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Book Description
Advances in Steam Turbines for Modern Power Plants provides an authoritative review of steam turbine design optimization, analysis and measurement, the development of steam turbine blades, and other critical components, including turbine retrofitting and steam turbines for renewable power plants. As a very large proportion of the world’s electricity is currently generated in systems driven by steam turbines, (and will most likely remain the case in the future) with steam turbines operating in fossil-fuel, cogeneration, combined cycle, integrated gasification combined cycle, geothermal, solar thermal, and nuclear plants across the world, this book provides a comprehensive assessment of the research and work that has been completed over the past decades. Presents an in-depth review on steam turbine design optimization, analysis, and measurement Written by a range of experts in the area Provides an overview of turbine retrofitting and advanced applications in power generation
Author: Augusto Di Gianfrancesco
Publisher: Woodhead Publishing
ISBN: 008100558X
Category : Business & Economics
Languages : en
Pages : 902
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Book Description
Materials for Ultra-Supercritical and Advanced Ultra-Supercritical Power Plants provides researchers in academia and industry with an essential overview of the stronger high-temperature materials required for key process components, such as membrane wall tubes, high-pressure steam piping and headers, superheater tubes, forged rotors, cast components, and bolting and blading for steam turbines in USC power plants. Advanced materials for future advanced ultra-supercritical power plants, such as superalloys, new martensitic and austenitic steels, are also addressed. Chapters on international research directions complete the volume. The transition from conventional subcritical to supercritical thermal power plants greatly increased power generation efficiency. Now the introductions of the ultra-supercritical (USC) and, in the near future, advanced ultra-supercritical (A-USC) designs are further efforts to reduce fossil fuel consumption in power plants and the associated carbon dioxide emissions. The higher operating temperatures and pressures found in these new plant types, however, necessitate the use of advanced materials. Provides researchers in academia and industry with an authoritative and systematic overview of the stronger high-temperature materials required for both ultra-supercritical and advanced ultra-supercritical power plants Covers materials for critical components in ultra-supercritical power plants, such as boilers, rotors, and turbine blades Addresses advanced materials for future advanced ultra-supercritical power plants, such as superalloys, new martensitic and austenitic steels Includes chapters on technologies for welding technologies
Author: Rizwan Ahmed Shaik
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Water Droplet Erosion (WDE) is a wear erosion phenomenon that is predominantly observed in gas, steam and wind turbines due to repetitive droplet impacts. In this work, various damage mechanisms pertaining to this phenomenon, described in the literature, are reviewed in detail. It was found that various surface treatments have been applied to delay the start of erosion in the material. However, in doing so the role of strain hardening was not well understood. In this work, a suitable material is identified to study the effect of strain hardening on the WDE performance. The material was characterized for various mechanical properties and for water droplet erosion. The material was also tested for WDE by performing a Deep Rolling (DR) treatment before testing. The erosion incubation time is analyzed by considering the yield strength, elastic resilience and strain hardening exponent. It was found that the erosion incubation time is dependent on the yield strength, elastic resilience and strain hardening exponent of the material. The role of strain hardening on WDE performance was also studied by intermittent strain relieving of the samples exposed to WDE. The frequency of strain relieving was found to influence the erosion behavior. It was observed that frequent strain relieving during WDE influences the erosion incubation time and the maximum erosion rate.
Author: Charles Bernardus Burson-Thomas
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Humberto Blanco-Canqui
Publisher: Springer Science & Business Media
ISBN: 1402087098
Category : Nature
Languages : en
Pages : 617
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Book Description
“Principles of Soil Management and Conservation” comprehensively reviews the state-of-knowledge on soil erosion and management. It discusses in detail soil conservation topics in relation to soil productivity, environment quality, and agronomic production. It addresses the implications of soil erosion with emphasis on global hotspots and synthesizes available from developed and developing countries. It also critically reviews information on no-till management, organic farming, crop residue management for industrial uses, conservation buffers (e.g., grass buffers, agroforestry systems), and the problem of hypoxia in the Gulf of Mexico and in other regions. This book uniquely addresses the global issues including carbon sequestration, net emissions of CO2, and erosion as a sink or source of C under different scenarios of soil management. It also deliberates the implications of the projected global warming on soil erosion and vice versa. The concern about global food security in relation to soil erosion and strategies for confronting the remaining problems in soil management and conservation are specifically addressed. This volume is suitable for both undergraduate and graduate students interested in understanding the principles of soil conservation and management. The book is also useful for practitioners, extension agents, soil conservationists, and policymakers as an important reference material.
Author: David R. Montgomery
Publisher: Univ of California Press
ISBN: 0520933168
Category : Nature
Languages : en
Pages : 299
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Book Description
Dirt, soil, call it what you want—it's everywhere we go. It is the root of our existence, supporting our feet, our farms, our cities. This fascinating yet disquieting book finds, however, that we are running out of dirt, and it's no laughing matter. An engaging natural and cultural history of soil that sweeps from ancient civilizations to modern times, Dirt: The Erosion of Civilizations explores the compelling idea that we are—and have long been—using up Earth's soil. Once bare of protective vegetation and exposed to wind and rain, cultivated soils erode bit by bit, slowly enough to be ignored in a single lifetime but fast enough over centuries to limit the lifespan of civilizations. A rich mix of history, archaeology and geology, Dirt traces the role of soil use and abuse in the history of Mesopotamia, Ancient Greece, the Roman Empire, China, European colonialism, Central America, and the American push westward. We see how soil has shaped us and we have shaped soil—as society after society has risen, prospered, and plowed through a natural endowment of fertile dirt. David R. Montgomery sees in the recent rise of organic and no-till farming the hope for a new agricultural revolution that might help us avoid the fate of previous civilizations.
