Analysis of Two-Phase Homogeneous Bubbly Flows Including Friction and Mass Addition

2004 ◽  
Vol 126 (1) ◽  
pp. 102-109 ◽  
Author(s):  
Marat Mor ◽  
Alon Gany
Keyword(s):  
Single Phase ◽  
Mathematical Formulation ◽  
Bubbly Flows ◽  
Wall Friction ◽  
Gas Flows ◽  
Propulsion Systems ◽  
Two Phase ◽  
Jet Propulsion ◽  
Flow Equations ◽  
Phase Velocities

The present work is a theoretical investigation of two-phase bubbly flows. The main objective is to get a better insight of the basic phenomena associated with such flows through nozzles via physical modeling and mathematical formulation. Introducing Mach number into the flow equations, we find novel, closed-form analytical solutions and expressions for homogeneous bubbly flows including the influence of wall friction and mass addition. The expressions obtained demonstrate an analogy to those of classical, single-phase gas flows. The study deals with homogeneous flows, however, its approach and results can also be applied to investigate flows with unequal phase velocities, to study instability phenomena, as well as to design and analyze water jet propulsion systems.

Modeling of Wall Friction for Multispecies Solid-Gas Flows

1986 ◽  
Vol 108 (4) ◽  
pp. 486-488 ◽  
Author(s):  
E. D. Doss ◽  
M. G. Srinivasan
Keyword(s):  
Shear Stress ◽  
Flow Model ◽  
Flow Characteristics ◽  
Wall Friction ◽  
Gas Flows ◽  
Two Phase ◽  
One Dimensional ◽  
Friction Models ◽  
Wall Interaction ◽  
The One

The empirical expressions for the equivalent friction factor to simulate the effect of particle-wall interaction with a single solid species have been extended to model the wall shear stress for multispecies solid-gas flows. Expressions representing the equivalent shear stress for solid-gas flows obtained from these wall friction models are included in the one-dimensional two-phase flow model and it can be used to study the effect of particle-wall interaction on the flow characteristics.

Flow of Incompressible Two-Phase Mixtures through Sharp-Edged Orifices

1967 ◽  
Vol 9 (1) ◽  
pp. 72-78 ◽  
Author(s):  
D. Chisholm
Keyword(s):  
Single Phase ◽  
Two Phase Flow ◽  
Weight Ratio ◽  
Liquid Mixtures ◽  
Theoretical Development ◽  
Phase Flow ◽  
Two Phase ◽  
Phase Velocities ◽  
Total Mixture ◽  
Good Agreement

Equations are developed for the flow of gas-liquid or vapour-liquid mixtures through sharp-edged orifices under conditions where the density change of the gas or liquid through the orifice is negligible. The theoretical development differs from previous treatments in allowing for the interfacial shear force between the phases, and leads to an equation which is shown to be in good agreement with available experimental evidence. The determination by experiment of a single coefficient characterizing the pipe and orifice arrangement permits the prediction of both the two-phase flow rate and the ratio of the phase velocities for a given pressure drop and gas-liquid weight ratio. The range of conditions examined extends over weight ratios of gas to total mixture from 0·1 to 98 per cent, and ratios of downstream to upstream pressures greater than 0·99. The accuracy of correlation of two-phase flow data is now approaching that of single-phase flow.

Countercurrent Flow Limitation in Slightly Inclined Pipes With Elbows

2015 ◽  
Vol 1 (4) ◽  
Author(s):  
Michio Murase ◽  
Ikuo Kinoshita ◽  
Takayoshi Kusunoki ◽  
Dirk Lucas ◽  
Akio Tomiyama
Keyword(s):  
Friction Coefficient ◽  
Single Phase ◽  
Wall Friction ◽  
Scale Model ◽  
Gas Flows ◽  
Countercurrent Flow ◽  
Flow Limitation ◽  
Adjustment Factor ◽  
Pressurized Water ◽  
Inclined Pipes

One-dimensional (1D) sensitivity computations were carried out for air–water countercurrent flows in a 1/15-scale model of the hot leg and a 1/10-scale model of the pressurizer surge line in a pressurized water reactor (PWR) to generalize the prediction method for countercurrent flow limitation (CCFL) characteristics in slightly inclined pipes with elbows. In the 1D model, the wall friction coefficient fwG of single-phase gas flows was used. The interfacial drag coefficient of fi=0.03, an appropriate adjustment factor of NwL=6 for the wall friction coefficient fwL of single-phase liquid flows (NwG=1 for fwG of single-phase gas flows), and an appropriate adjustment factor of Nde=6 for the pressure loss coefficient ζe of elbows in single-phase flows were determined to give good agreement between the computed and measured CCFL characteristics. The adjusted factors were used to compute and then discuss effects of the inclination angle and diameter on CCFL characteristics.

High-Resolution Simulations for Aerogel Using Two-Phase Flow Equations and Godunov Methods

2020 ◽  
Vol 12 (05) ◽  
pp. 2050049 ◽  
Author(s):  
D. Zeidan ◽  
L. T. Zhang ◽  
E. Goncalves
Keyword(s):  
Single Phase ◽  
Two Phase Flow ◽  
Equilibrium Mixture ◽  
Phase Flow ◽  
Two Phase ◽  
One Dimensional ◽  
Flow Equations ◽  
System A ◽  
Godunov Methods ◽  
Remarkable Agreement

Aerogel is studied numerically using a one-dimensional two-phase flow equations system. A hyperbolic and conservative two-phase flow model is applied to a mixture of porous media containing nanofluids. The application of non-equilibrium mixture behavior between phases is adopted and promoted in this current investigation. By establishing mixture conservation balance laws, finite volume techniques using Godunov methods of centered type are extended to aerogel simulations. Numerical results are compared with other methods providing a remarkable agreement. The computed results demonstrate the key capabilities of this existing mixture model in the resolution of discontinuities in aerogel problems and more reliable than applying a sophisticated single-phase flows with complex property models.

Non-isothermal Laminar Flow of Gases through Cooled Tubes

1973 ◽  
Vol 95 (1) ◽  
pp. 85-92 ◽  
Author(s):  
Lloyd H. Back
Keyword(s):  
Laminar Flow ◽  
Numerical Solutions ◽  
Isothermal Flow ◽  
Wall Friction ◽  
Gas Flows ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Flow Equations ◽  
Flow Through ◽  
Good Agreement

Numerical solutions of the laminar-flow equations in differential form are presented for gas flows through cooled tubes. For nearly isothermal flow there is good agreement with available experimental data, as is also found for the case of a large amount of wall cooling. This correspondence along with a check on the satisfaction of the global momentum and energy constraints allowed an appraisal of the effect of wall cooling on flow through tubes. In general, the effect of wall cooling was to decrease the wall friction and the change in pressure along tubes, but the average heat-transfer coefficient did not vary much.

A TEM study of the influence of microstructure on the superplastic behavior of a U-5.8 wt.% Nb alloy

1986 ◽  
Vol 44 ◽  
pp. 568-569
Author(s):  
G. Mackiewicz Ludtka
Keyword(s):  
Grain Size ◽  
Heating Rate ◽  
Phase Field ◽  
Single Phase ◽  
Superplastic Behavior ◽  
Two Phase ◽  
Single Phase Field

Historically, metals exhibit superplasticity only while forming in a two-phase field because a two-phase microstructure helps ensure a fine, stable grain size. In the U-5.8 Nb alloy, superplastici ty exists for up to 2 h in the single phase field (γ1) at 670°C. This is above the equilibrium monotectoid temperature of 647°C. Utilizing dilatometry, the superplastic (SP) U-5.8 Nb alloy requires superheating to 658°C to initiate the α+γ2 → γ1 transformation at a heating rate of 1.5°C/s. Hence, the U-5.8 Nb alloy exhibits an anomolous superplastic behavior.

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