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Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781721080311 Category : Languages : en Pages : 158
Book Description
The present work reports a study of bubble generation under reduced gravity conditions for both co-flow and cross-flow configurations. Experiments were performed aboard the DC-9 Reduced Gravity Aircraft at NASA Glenn Research Center, using an air-water system. Three different flow tube diameters were used: 1.27, 1.9, and 2.54 cm. Two different ratios of air injection nozzle to tube diameters were considered: 0.1 and 0.2. Gas and liquid volumetric flow rates were varied from 10 to 200 ml/s. It was experimentally observed that with increasing superficial liquid velocity, the bubbles generated decreased in size. The bubble diameter was shown to increase with increasing air injection nozzle diameters. As the tube diameter was increased, the size of the detached bubbles increased. Likewise, as the superficial liquid velocity was increased, the frequency of bubble formation increased and thus the time to detach forming bubbles decreased. Independent of the flow configuration (for either single nozzle or multiple nozzle gas injection), void fraction and hence flow regime transition can be controlled in a somewhat precise manner by solely varying the gas and liquid volumetric flow rates. On the other hand, it is observed that uniformity of bubble size can be controlled more accurately by using single nozzle gas injection than by using multiple port injection, since this latter system gives rise to unpredictable coalescence of adjacent bubbles. A theoretical model, based on an overall force balance, is employed to study single bubble generation in the dynamic and bubbly flow regime. Under conditions of reduced gravity, the gas momentum flux enhances bubble detachment; however, the surface tension forces at the nozzle tip inhibits bubble detachment. Liquid drag and inertia can act either as attaching or detaching force, depending on the relative velocity of the bubble with respect to the surrounding liquid. Predictions of the theoretical model compare well with performed expe
Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781721080311 Category : Languages : en Pages : 158
Book Description
The present work reports a study of bubble generation under reduced gravity conditions for both co-flow and cross-flow configurations. Experiments were performed aboard the DC-9 Reduced Gravity Aircraft at NASA Glenn Research Center, using an air-water system. Three different flow tube diameters were used: 1.27, 1.9, and 2.54 cm. Two different ratios of air injection nozzle to tube diameters were considered: 0.1 and 0.2. Gas and liquid volumetric flow rates were varied from 10 to 200 ml/s. It was experimentally observed that with increasing superficial liquid velocity, the bubbles generated decreased in size. The bubble diameter was shown to increase with increasing air injection nozzle diameters. As the tube diameter was increased, the size of the detached bubbles increased. Likewise, as the superficial liquid velocity was increased, the frequency of bubble formation increased and thus the time to detach forming bubbles decreased. Independent of the flow configuration (for either single nozzle or multiple nozzle gas injection), void fraction and hence flow regime transition can be controlled in a somewhat precise manner by solely varying the gas and liquid volumetric flow rates. On the other hand, it is observed that uniformity of bubble size can be controlled more accurately by using single nozzle gas injection than by using multiple port injection, since this latter system gives rise to unpredictable coalescence of adjacent bubbles. A theoretical model, based on an overall force balance, is employed to study single bubble generation in the dynamic and bubbly flow regime. Under conditions of reduced gravity, the gas momentum flux enhances bubble detachment; however, the surface tension forces at the nozzle tip inhibits bubble detachment. Liquid drag and inertia can act either as attaching or detaching force, depending on the relative velocity of the bubble with respect to the surrounding liquid. Predictions of the theoretical model compare well with performed expe
Author: Hao Zhang Publisher: Trans Tech Publications Ltd ISBN: 3038137472 Category : Technology & Engineering Languages : en Pages : 1441
Book Description
Selected, peer reviewed papers from the 2011 International Conference on Energy, Environment and Sustainable Development (ICEESD 2011), October 21-23, 2011, Shanghai, China
Author: W Gao Publisher: Elsevier ISBN: 1845694252 Category : Technology & Engineering Languages : en Pages : 677
Book Description
High temperature corrosion is a phenomenon that occurs in components that operate at very high temperatures, such as gas turbines, jet engines and industrial plants. Engineers are constantly striving to understand and prevent this type of corrosion. This book examines the latest developments in the understanding of high temperature corrosion processes and protective oxide scales and coatings.Part one looks at high temperature corrosion. Chapters cover diffusion and solid state reactions, external and internal oxidation of alloys, metal dusting corrosion, tribological degradation, hot corrosion, and oxide scales on hot-rolled steel strips. Modern techniques for analysing high temperature oxidation and corrosion are also discussed. Part two discusses methods of protection using ceramics, composites, protective oxide scales and coatings. Chapters focus on layered ternary ceramics, alumina scales, Ti-Al intermetallic compounds, metal matrix composites, chemical vapour deposited silicon carbide, nanocrystalline coatings and thermal barrier coatings. Part three provides case studies illustrating some of the challenges of high temperature corrosion to industry and how they can be overcome. Case studies include the petrochemical industry, modern incinerators and oxidation processing of electronic materials.This book is a valuable reference tool for engineers who develop heat resistant materials, mechanical engineers who design and maintain high temperature equipment and plant, and research scientists and students who study high temperature corrosion and protection of materials. - Describes the latest developments in understanding high temperature corrosion - Presents the latest research by the leading innovators from around the globe - Case studies are provided to illustrate key points
Author: M. I. Ismail Publisher: Elsevier Publishing Company ISBN: Category : Science Languages : en Pages : 574
Book Description
This book provides a guide for professionals interested in energy transfer and electrochemical technology systems. It covers the state-of-the-art of materials, electrochemistry and electrochemical engineering as related to electrochemical reactors, batteries and fuel cells. The fifteen chapters, written by experts in fields related to every aspect affecting reactor performance, are grouped into three parts. The first is devoted to fundamentals of reactors, batteries and fuel cells and covers various aspects of design, parts, construction, materials operation and control systems. The second group is devoted to specific reactors such as aqueous electro-organic and inorganic synthesis, electrochemical polymerization, molten salt electrolysis, electrochemical machining, metal finishing, reactor performance, failure mechanisms, corrosion control, materials selection and techniques. The third group deals with manufacturing techniques and surface treatment of materials for commercial reactors, commercial parts/materials, fastening, assembly and production of reactor parts and mathematical modelling of various reactor processes.
Author: Rodolfo Monti Publisher: CRC Press ISBN: 9780415275811 Category : Science Languages : en Pages : 630
Book Description
In a microgravity experiment, the conditions prevalent in fluid phases can be substantially different from those on the ground and can be exploited to improve different processes. Fluid physics research in microgravity is important for the advancement of all microgravity scients: life, material, and engineering. Space flight provides a unique laboratory that allows scientists to improve their understanding of the behaviour of fluids in low gravity, allowing the investigation of phenomena and processes normally masked by the effects of gravity and thus difficult to study on Earth. Physics of Fluids in Microgravity provides a clear view of recent research and progress in the different fields of fluid research in space. The topics presented include bubles and drops dynamics, Maragoni flows, diffustion and thermodiffusion, solidfication,a nd crystal growth. The results obtained so far are, in some cases, to be confirmed by extensive research activities on the International Space station, where basic and applied microgravity experimentation will take place in the years to come.
Author: Martin Sommerfeld Publisher: Springer Science & Business Media ISBN: 3642185401 Category : Science Languages : en Pages : 354
Book Description
The book summarises the outcom of a priority research programme: 'Analysis, Modelling and Computation of Multiphase Flows'. The results of 24 individual research projects are presented. The main objective of the research programme was to provide a better understanding of the physical basis for multiphase gas-liquid flows as they are found in numerous chemical and biochemical reactors. The research comprises steady and unsteady multiphase flows in three frequently found reactor configurations, namely bubble columns without interiors, airlift loop reactors, and aerated stirred vessels. For this purpose new and improved measurement techniques were developed. From the resulting knowledge and data, new and refined models for describing the underlying physical processes were developed, which were used for the establishment and improvement of analytic as well as numerical methods for predicting multiphase reactors. Thereby, the development, lay-out and scale-up of such processes should be possible on a more reliable basis.
Author: National Aeronautics and Space Administration (NASA)
Author: National Aeronautics and Space Administration (NASA)
Author: Salvatore Cezar Pais
Author: Hao Zhang
Author: W Gao
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Author: 
Author: 
Author: M. I. Ismail
Author: Rodolfo Monti
Author: Martin Sommerfeld