Studies of Two-Phase Flow Dynamics and Heat Transfer at Reduced Gravity Conditions PDF Download
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722817558
Category :
Languages : en
Pages : 44
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Book Description
The ability to predict gas-liquid flow patterns is crucial to the design and operation of two-phase flow systems in the microgravity environment. Flow pattern maps have been developed in this study which show the occurrence of flow patterns as a function of gas and liquid superficial velocities as well as tube diameter, liquid viscosity and surface tension. The results have demonstrated that the location of the bubble-slug transition is affected by the tube diameter for air-water systems and by surface tension, suggesting that turbulence-induced bubble fluctuations and coalescence mechanisms play a role in this transition. The location of the slug-annular transition on the flow pattern maps is largely unaffected by tube diameter, liquid viscosity or surface tension in the ranges tested. Void fraction-based transition criteria were developed which separate the flow patterns on the flow pattern maps with reasonable accuracy. Weber number transition criteria also show promise but further work is needed to improve these models. For annular gas-liquid flows of air-water and air- 50 percent glycerine under reduced gravity conditions, the pressure gradient agrees fairly well with a version of the Lockhart-Martinelli correlation but the measured film thickness deviates from published correlations at lower Reynolds numbers. Nusselt numbers, based on a film thickness obtained from standard normal-gravity correlations, follow the relation, Nu = A Re(sup n) Pr(exp l/3), but more experimental data in a reduced gravity environment are needed to increase the confidence in the estimated constants, A and n. In the slug flow regime, experimental pressure gradient does not correlate well with either the Lockhart-Martinelli or a homogeneous formulation, but does correlate nicely with a formulation based on a two-phase Reynolds number. Comparison with ground-based correlations implies that the heat transfer coefficients are lower at reduced gravity than at normal gravity under the same ...
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722817558
Category :
Languages : en
Pages : 44
Get Book
Book Description
The ability to predict gas-liquid flow patterns is crucial to the design and operation of two-phase flow systems in the microgravity environment. Flow pattern maps have been developed in this study which show the occurrence of flow patterns as a function of gas and liquid superficial velocities as well as tube diameter, liquid viscosity and surface tension. The results have demonstrated that the location of the bubble-slug transition is affected by the tube diameter for air-water systems and by surface tension, suggesting that turbulence-induced bubble fluctuations and coalescence mechanisms play a role in this transition. The location of the slug-annular transition on the flow pattern maps is largely unaffected by tube diameter, liquid viscosity or surface tension in the ranges tested. Void fraction-based transition criteria were developed which separate the flow patterns on the flow pattern maps with reasonable accuracy. Weber number transition criteria also show promise but further work is needed to improve these models. For annular gas-liquid flows of air-water and air- 50 percent glycerine under reduced gravity conditions, the pressure gradient agrees fairly well with a version of the Lockhart-Martinelli correlation but the measured film thickness deviates from published correlations at lower Reynolds numbers. Nusselt numbers, based on a film thickness obtained from standard normal-gravity correlations, follow the relation, Nu = A Re(sup n) Pr(exp l/3), but more experimental data in a reduced gravity environment are needed to increase the confidence in the estimated constants, A and n. In the slug flow regime, experimental pressure gradient does not correlate well with either the Lockhart-Martinelli or a homogeneous formulation, but does correlate nicely with a formulation based on a two-phase Reynolds number. Comparison with ground-based correlations implies that the heat transfer coefficients are lower at reduced gravity than at normal gravity under the same ...
Author: Basil N. Antar
Publisher: CRC Press
ISBN: 1351080636
Category : Technology & Engineering
Languages : en
Pages : 312
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Book Description
This book presents the fundamentals of low gravity fluid dynamics and heat transfer. It investigates fluid behavior in low gravity environments such as those found in earth orbiting and space vehicles. The two major fluid phenomena affected by gravity (buoyancy and surface tension) are treated thoroughly from both the theoretical and applications points of view, and limitations of fluid and thermal responses to gravitational fields in space-based settings are clearly delineated. Summaries of all data available from low gravity flight and terrestrial experiments performed to date are also presented.
Author: Kamiel S. Gabriel
Publisher: Springer Science & Business Media
ISBN: 1402051433
Category : Technology & Engineering
Languages : en
Pages : 252
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Book Description
Multiphase thermal systems have numerous applications in aerospace, heat-exchange, transport of contaminants in environmental systems, and energy transport and conversion systems. A reduced - or microgravity - environment provides an excellent tool for accurate study of the flow without the masking effects of gravity. This book presents for the first time a comprehensive coverage of all aspects of two-phase flow behaviour in the virtual absence of gravity.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 44
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Book Description
Author: Mirza Mohammed Shah
Publisher: John Wiley & Sons
ISBN: 1119618614
Category : Science
Languages : en
Pages : 388
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Book Description
A guide to two-phase heat transfer theory, practice, and applications Designed primarily as a practical resource for design and development engineers, Two-Phase Heat Transfer contains the theories and methods of two-phase heat transfer that are solution oriented. Written in a clear and concise manner, the book includes information on physical phenomena, experimental data, theoretical solutions, and empirical correlations. A very wide range of real-world applications and formulas/correlations for them are presented. The two-phase heat transfer systems covered in the book include boiling, condensation, gas-liquid mixtures, and gas-solid mixtures. The authora noted expert in this fieldalso reviews the numerous applications of two-phase heat transfer such as heat exchangers in refrigeration and air conditioning, conventional and nuclear power generation, solar power plants, aeronautics, chemical processes, petroleum industry, and more. Special attention is given to heat exchangers using mini-channels which are being increasingly used in a variety of applications. This important book: Offers a practical guide to two-phase heat transfer Includes clear guidance for design professionals by identifying the best available predictive techniques Reviews the extensive literature on heat transfer in two-phase systems Presents information to aid in the design and analysis of heat exchangers. Written for students and research, design, and development engineers, Two-Phase Heat Transfer is a comprehensive volume that covers the theory, methods, and applications of two-phase heat transfer.
Author: National Aeronautics and Space Adm Nasa
Publisher:
ISBN: 9781730990052
Category :
Languages : en
Pages : 96
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Book Description
The design of the two-phase flow systems which are anticipated to be utilized in future spacecraft thermal management systems requires a knowledge of two-phase flow and heat transfer phenomena in reduced gravities. This program was funded by NASA headquarters in response to NRA-91-OSSA-17 and was managed by Lewis Research Center. The main objective of this program was to design and construct a two-phase test loop, and perform a series of normal gravity and aircraft trajectory experiments to study the effect of gravity on the Critical Heat Flux (CHF) and onset of instability. The test loop was packaged on two aircraft racks and was also instrumented to generate data for two-phase pressure drop. The normal gravity tests were performed with vertical up and downflow configurations to bound the effect of gravity on the test parameters. One set of aircraft trajectory tests was performed aboard the NASA DC-9 aircraft. These tests were mainly intended to evaluate the test loop and its operational performance under actual reduced gravity conditions, and to produce preliminary data for the test parameters. The test results were used to demonstrate the applicability of the normal gravity models for prediction of the two-phase friction pressure drop. It was shown that the two-phase friction multipliers for vertical upflow and reduced gravity conditions can be successfully predicted by the appropriate normal gravity models. Limited critical heat flux data showed that the measured CHF under reduced gravities are of the same order of magnitude as the test results with vertical upflow configuration. A simplified correlation was only successful in predicting the measured CHF for low flow rates. Instability tests with vertical upflow showed that flow becomes unstable and critical heat flux occurs at smaller powers when a parallel flow path exists. However, downflow tests and a single reduced gravity instability experiment indicated that the system actually became more stable with a p...
Author: Lixin Cheng
Publisher: Bentham Science Publishers
ISBN: 1608050807
Category : Science
Languages : en
Pages : 296
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Book Description
"Multiphase flow and heat transfer have found a wide range of applications in several engineering and science fields such as mechanical engineering, chemical and petrochemical engineering, nuclear engineering, energy engineering, material engineering, ocea"
Author: S. Stephen Papell
Publisher:
ISBN:
Category : Resistance heating
Languages : en
Pages : 24
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Book Description
Subcritical, subcooled boiling heat-transfer data were obtained for distilled water flowing through a resistance-heated tube in a gravity-free environment lasting approximately 15 seconds. Two types of flow models were found to exist under identical test conditions. An instability initiated by a momentary interruption of flow forced the transition from a highly subcooled bubbly flow to a postulated slug flow that resulted in a 16-percent increase in local heat-transfer coefficients. The slug-flow regime was described as consisting of two phases in a highly nonequilibrium thermodynamic state. A duplication of test conditions that produced the transition in a zero-gravity environment failed to do so under Earth-gravity conditions.
Author:
Publisher: Academic Press
ISBN: 0128124121
Category : Science
Languages : en
Pages : 332
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Book Description
Advances in Heat Transfer, Volume 49 provides in-depth review articles from a broader scope than in traditional journals or texts. Topics covered in this new volume include Heat Transfer in Rotating Cooling Channel, Flow Boiling and Flow Condensation in Reduced Gravity, Advances in Gas Turbine Cooling, and Advanced Heat Transfer Topics in Complex Duct Flows. While the articles in this series will be of great interest to mechanical, chemical and industrial engineers working in the field of heat transfer, the book is also ideal for those in graduate schools or industry, and even non-specialists interested in the latest research. Compiles the expert opinions of leaders in the industry Fills the information gap between regularly scheduled journals and university-level textbooks by providing in-depth review articles over a broader scope than in traditional journals or texts Essential reading for all mechanical, chemical and industrial engineers working in the field of heat transfer, or in graduate schools or industry
Author: Rodolfo Monti
Publisher: CRC Press
ISBN: 9780415275811
Category : Science
Languages : en
Pages : 630
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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.
