Download or read book Microgravity Liquid gas Two phase Flow written by Ramaswamy Balasubramaniam and published by . This book was released on 2019 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Prediction of Gas liquid Two phase Flow Regime in Microgravity written by Jinho Lee and published by . This book was released on 1993 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scaling Analysis of Gas liquid Two phase Flow Pattern in Microgravity written by Jinho Lee and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Prediction of Gas Liquid Two Phase Flow Regime in Microgravity written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-10 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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...

Download or read book Microgravity Two phase Flow and Heat Transfer written by Kamiel S. Gabriel and published by Springer Science & Business Media. This book was released on 2007-05-10 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Studies of Two phase Gas liquid Flow in Microgravity written by William Scott Bousman and published by . This book was released on 1995 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics of Fluids in Microgravity written by Rodolfo Monti and published by CRC Press. This book was released on 2002-01-10 with total page 630 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Studies of Two Phase Flow Dynamics and Heat Transfer at Reduced Gravity Conditions written by and published by . This book was released on 1996 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Analysis of Two phase Flows in Conditions Relevant to Microgravity written by Santiago Arias Calderon and published by . This book was released on 2013 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Analysis of Two phase Flows Under Microgravity spatial Conditions Using OpenFOAM written by Carlos Moreno Tavira and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-phase flows have gained importance over the last years due to their multiple and useful applications in space systems. For example, two-phase flows are used in fuel cells micro-channel networks, in the fluid management of Environmental Control and Life Support Systems (ECLSS) or in thermal management systems. However, many problems regarding two-phase flows in microgravity conditions are still open, so further research is needed. In this study, numerical simulations of gas-liquid two-phase flow are performed in a T-junction capillary. Bubbles are formed as a consequence of the interaction between air and water. The geometry used is the same as in [1, 2, 3] in order to make reliable comparisons with the results extracted from the laboratory experiments performed in the mentioned literature. OpenFOAM is used as the main software for the simulations, and ParaView and MATLAB are used to post-process the data. InterFoam is selected as the solver since it uses an incompressible, immiscible and isothermal Volume of Fluid (VOF) method. Some validations were made before setting up the definitive cases of the simulations. These validations were related to the adequate capillary length in order to obtain fully-developed flows, to the appropriate mesh quality to get good results and maintain an acceptable computational complexity, to the optimal contact angle value to get close to reality bubble behavior in terms of adherence to the walls, and to the right location of the sampling surfaces responsible for extracting the data. An analysis of the fluid velocity profiles along both of the capillaries of the T-junction was also made. Bubbles are analyzed in terms of their generating frequency, volume, length and velocity. Bubble volume dispersion is quantified using the polydispersity index. A pressure probe is used to measure the gauge pressure at the very center of the T-junction. Visual comparisons are made between simulation bubbles and experimental bubbles. In the end, the results of the simulations qualitatively fitted the experimental data, validating Computational Fluid Dynamics (CFD) as an alternative and correct tool to perform two-phase flow studies under microgravity conditions.

Download or read book Second Microgravity Fluid Physics Conference written by and published by . This book was released on 1994 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Design Manual for Microgravity Two Phase Flow and Heat Transfer written by Christopher J. Crowley and published by . This book was released on 1989 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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).

Download or read book Gas liquid Two phase Flow Through Packed Bed Reactors in Microgravity written by Brian J. Motil and published by . This book was released on 2006 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analytical and Experimental Study of Annular Two phase Flow Friction Pressure Drop Under Microgravity written by Ngoc Thanh Nguyen and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-phase liquid-gas flow has a wide variety of applications in space, including active thermal control systems, high-power communications satellites, heat pumps and space nuclear reactors. Two-phase systems have many potential advantages over current single-phase systems due to reductions in system size, weight and power consumption. The mechanisms of pressure drop, heat transfer coefficients, void fractions, and flow regimes must be well understood under microgravity conditions in order to design reliable two-phase systems. The main objective of this present research is to develop a new mathematical model that can accurately predict the annular two-phase friction pressure drop to optimize the design of two-phase systems. The two-phase flow tests were conducted aboard the NASA KC-135 aircraft by the Interphase Transport Phenomena (ITP) group from Texas A & M University. The two-phase flow pressure drops were measured across a single transparent test section 12.7 mm ID and 1.63 m long in annular regimes under microgravity conditions during two flight campaigns. Different from previous work, this was the first time both the void fraction and the film thickness were measured under microgravity conditions. The empirical correlations for the interfacial friction factor and void fraction were developed from 57 experimental data using a linear least squares regression technique. The annular two-phase friction pressure drop can be predicted by the new mathematical model requiring only knowledge of the length and diameter of the tube, liquid and vapor mass flow rates, and properties of the working fluid. In addition, the new mathematical model was validated using Foster-Miller & ITP data collected over twelve flights aboard the KC-135 with working fluid R-12 (77 data points), Sundstrand data collected aboard the KC-135 with working fluid R-114 (43 data points) and Zhao and Rezkallah data aboard the KC-135 with working fluid water and air (43 data points). Compared with the LockhartMartinelli model, Wheeler model, Chen model and homogeneous model, the new mathematical model is the optimal model for predicting the two-phase friction pressure drop in annular regimes. The majority of the data falls within +-20% of the proposed correlation and the average error is 12%.

Download or read book Studies of Two Phase Flow Dynamics and Heat Transfer at Reduced Gravity Conditions written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-11 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 ...

Download or read book Experimental and Numerical Investigations of Two Phase Flow with Non Isothermal Boundary Conditions under Microgravity Conditions written by Sebastian Schmitt and published by Cuvillier Verlag. This book was released on 2017-03-06 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-phase flow with a free surface, non-isothermal boundary conditions and heat and mass transfer over the free surface must be understood for a save operation of cryogenic upper stages with restart capability. This work is a foundational research carried out with numerical and experimental means. A mathematical and numerical model were developed that allow to describe such systems under varying gravity levels. The reorientation of cryogenic parahydrogen upon a sudden gravity step reduction was investigated experimentally using the drop tower at ZARM, University of Bremen. Influencing the motion and final shape of the free surface could be realized with a precisely defined wall temperature gradient. Heat and mass transfer over the free surface in a microgravity environment could be investigated numerically based on the experimental results of the SOURCE-II sounding rocket experiment. A transient simulation was carried out to study the coupled system between superheated container wall, subcooled liquid, free surface configuration and three-phase contact angle.

Download or read book Flow Patterns Pressure Drops and Other Related Topics of Two Phase Gas Liquid Flow in Microgravity written by Jian-Fu Zhao and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: