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Author: National Aeronautics and Space Adm Nasa Publisher: Independently Published ISBN: 9781729233887 Category : Science Languages : en Pages : 44
Book Description
An attempt is made to predict gas-liquid two-phase flow regime in a pipe in a microgravity environment through scaling analysis based on dominant physical mechanisms. Simple inlet geometry is adopted in the analysis to see the effect of inlet configuration on flow regime transitions. Comparison of the prediction with the existing experimental data shows good agreement, though more work is required to better define some physical parameters. The analysis clarifies much of the physics involved in this problem and can be applied to other configurations. Lee, Jinho and Platt, Jonathan A. Glenn Research Center RTOP 694-03-0A
Author: National Aeronautics and Space Adm Nasa Publisher: Independently Published ISBN: 9781729233887 Category : Science Languages : en Pages : 44
Book Description
An attempt is made to predict gas-liquid two-phase flow regime in a pipe in a microgravity environment through scaling analysis based on dominant physical mechanisms. Simple inlet geometry is adopted in the analysis to see the effect of inlet configuration on flow regime transitions. Comparison of the prediction with the existing experimental data shows good agreement, though more work is required to better define some physical parameters. The analysis clarifies much of the physics involved in this problem and can be applied to other configurations. Lee, Jinho and Platt, Jonathan A. Glenn Research Center RTOP 694-03-0A
Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781721033379 Category : Languages : en Pages : 74
Book Description
The purpose of this report is to provide a summary of state-of-the-art predictions for two-phase flows relevant to Advanced Life Support. We strive to pick out the most used and accepted models for pressure drop and flow regime predictions. The main focus is to identify gaps in predictive capabilities in partial gravity for Lunar and Martian applications. Following a summary of flow regimes and pressure drop correlations for terrestrial and zero gravity, we analyze the fully developed annular gas-liquid flow in a straight cylindrical tube. This flow is amenable to analytical closed form solutions for the flow field and heat transfer. These solutions, valid for partial gravity as well, may be used as baselines and guides to compare experimental measurements. The flow regimes likely to be encountered in the water recovery equipment currently under consideration for space applications are provided in an appendix.Balasubramaniam, R. and Rame, E. and Kizito, J. and Kassemi, M.Glenn Research CenterFLOW DISTRIBUTION; LIFE SUPPORT SYSTEMS; TWO PHASE FLOW; LIQUID-GAS MIXTURES; TECHNOLOGY UTILIZATION; ANNULAR FLOW; HEAT TRANSFER; MARS (PLANET); PREDICTIONS; WATER RECLAMATION
Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781722817558 Category : Languages : en Pages : 44
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: Kamiel S. Gabriel Publisher: Springer Science & Business Media ISBN: 1402051433 Category : Technology & Engineering Languages : en Pages : 252
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: Santiago Arias Calderon Publisher: ISBN: Category : Languages : en Pages : 164
Book Description
Promising technological applications of two-phase flows in space have captured the increasing interest of the space sector, provoking a strong demand for more fundamental knowledge. Great efforts have been made in recent decades to study the behavior of two-phase flows in low-gravity environments, which is expected to be different than the behavior observed in the presence of gravitational forces. Nevertheless, many phenomena are still poorly understood. The development of any of these new technologies demands a better knowledge of two-phase flows. In this manuscript we address questions regarding the generation of gas-liquid flows and their behavior in conditions relevant for a microgravity environment. In particular, we focus on an air-water mixture formed in a capillary T-junction. To this end, an experimental setup has been designed to accurately control both gas and liquid flow rates. We performed a quantitative characterization on ground of the T-junction, whose operation is robust to changes in gravity level. Its main performance is the generation of bubbles at a regular frequency with small size dispersion. We obtained two working regimes of the T-junction and identified the crossover region between them. Bubble, slug, churn and annular flow regimes have been observed during the experiments and a flow pattern map has been plotted. We present an experimental study on the bubble-slug transition in microgravity-related conditions. In addition, we address questions regarding the existence of a critical void fraction in order for the bubble-slug transition to occur. The gas-liquid flow has been characterized by measuring the bubble generation frequency as well as the bubble and liquid slug sizes. Since bubble dynamics is also expected to be different in the absence of buoyancy, the bubble velocity has also been studied. The mean void fraction appears as one relevant parameter that allows for the prediction of frequency, bubble velocity, and lengths. We propose curves obtained empirically for the behavior of generation frequency, the bubble velocity and the lengths. The dependence of the frequency on the Strouhal dimensionless number has been analyzed. A numerical study of the formation of mini-bubbles in a 2D T-junction by means of the fluid dynamics numerical code JADIM is also presented. Simulations were carried out for different flow conditions, giving rise to results on the bubble generation frequency, bubble velocity, void fraction and characteristic lengths. Numerical results have been then compared with experimental data.
Author: Christopher J. Crowley Publisher: ISBN: Category : Languages : en Pages : 143
Book Description
This report documents two-phase fluid flow and heat transfer methods for microgravity environments. The applications of the work are thermal management, propulsion, and fluid storage and transfer systems for spacecraft. In the near future, these systems will include two-phase, vapor-liquid flows. This Design Manual is intended for use by designers of these systems. Design methods are presented for predicting two-phase flow regimes and pressure drops in pipe flows from earth gravity to microgravity conditions. Forced convection boiling heat transfer methods for pipes with uniform heat flux are included. Also included are methods for analyzing high-vapor-shear condensation in pipes. The analysis methods are mechanistic; that is, based upon fundamental physical principles which should apply to heat transfer liquids with Pr approx = 1 and scale with pipe size and fluid properties. This Manual incorporates simplified methods (easy-to-use design charts), detailed descriptions of the analysis methods, comparisons with existing microgravity data, and recommended approaches to quantify the range of uncertainty in design calculations. Keywords: Fluid flow; Heat transfer; Space technology; Spacecraft components; Thermodynamics; Two phase flow. (jhd).
Author: National Aeronautics and Space Adm Nasa
Author: National Aeronautics and Space Adm Nasa
Author: Jinho Lee
Author: National Aeronautics and Space Administration (NASA)
Author: Jinho Lee
Author: National Aeronautics and Space Administration (NASA)
Author: Kamiel S. Gabriel
Author: William Scott Bousman
Author: Santiago Arias Calderon
Author: 
Author: Christopher J. Crowley