Steam Slip—Theoretical Prediction From Momentum Model

1960 ◽  
Vol 82 (2) ◽  
pp. 113-124 ◽  
Author(s):  
S. Levy
Keyword(s):  
Two Phase ◽  
Forced Circulation ◽  
Channel Geometry ◽  
Pressure Drops ◽  
Head Losses ◽  
Heat Addition ◽  
Slip Effects ◽  
Two Phases ◽  
Vertical Test ◽  
Good Agreement

Theoretical equations governing slip effects in forced circulation of boiling water are derived. The equations indicate that steam slip is dependent upon channel geometry, inlet water velocity, and rate of heat addition. A simplified momentum model is postulated which leads to equal friction and head losses of two phases. The model gives good agreement with available experimental results in horizontal and vertical test sections with and without heat addition at pressures from 12 to 2000 psia. Discussion of the model in terms of nonquasi steady-state unbalances of friction and head losses of the two phases explains experimental deviations from the predictions and the previously noted effects of water inlet velocity. It also gives trends for the effects of channel geometry and rate of heat addition. Application of the simplified model to calculating two-phase pressure drops is included.

Prediction of Two-Phase Pressure Drop and Density Distribution From Mixing Length Theory

1963 ◽  
Vol 85 (2) ◽  
pp. 137-150 ◽  
Author(s):  
S. Levy
Keyword(s):  
Single Phase ◽  
Continuous Medium ◽  
Phase System ◽  
Mixing Length ◽  
Test Results ◽  
Two Phase ◽  
Pressure Drops ◽  
Mixing Length Theory ◽  
Phase Pressure ◽  
Good Agreement

Single-phase turbulent mixing length methods are used to predict two-phase flow. Two-phase density and velocity distributions and two-phase pressure drops are derived by treating the two-phase system as a continuous medium where the turbulent exchanges of momentum and density are equal. Good agreement is obtained between test results and analytical predictions.

Entrance Effects in a Two-Phase Slug Flow

1962 ◽  
Vol 84 (1) ◽  
pp. 29-38 ◽  
Author(s):  
R. Moissis ◽  
P. Griffith
Keyword(s):  
Slug Flow ◽  
Present Theory ◽  
Separation Distance ◽  
Rise Velocity ◽  
Two Phase ◽  
Developing Flow ◽  
Two Phases ◽  
Kinetics Of ◽  
Theory And Experiments ◽  
Good Agreement

This paper describes quantitatively one stage of the flow development process in equipment working with two-phase mixtures. The kinetics of a Taylor bubble, as it rises behind a series of other bubbles in a gas-liquid slug flow, have been determined. The rise velocity of a bubble is expressed as a function of separation distance from the bubble ahead of it. Using this information, the pattern of development of bubbles which initially enter a tube at regular intervals is determined by means of finite difference calculations. The density and, to a first approximation the pressure drop, of the developing flow are then calculated from continuity considerations. The density distribution in the entrance region is found to be a function of flow rates of the two phases, of distance from the inlet, and of initial bubble size. Density calculated by the present theory is compared with experimental measurements by the present and other investigators. Theory and experiments are in good agreement.

A NOVEL MODEL OF DIELECTRIC CONSTANT OF TWO-PHASE COMPOSITES WITH INTERFACIAL SHELLS

2002 ◽  
Vol 16 (25) ◽  
pp. 3855-3863 ◽  
Author(s):  
QINGZHONG XUE
Keyword(s):  
Dielectric Constant ◽  
Effective Dielectric Constant ◽  
Maxwell Theory ◽  
Two Phase ◽  
Random Composites ◽  
Polarization Theory ◽  
Two Phases ◽  
Novel Model ◽  
Theoretical Results ◽  
Good Agreement

Considering the interface effect between two phases in composite, we present a novel model of dielectric constant of two-phase composites with interfacial shells. Starting from Maxwell theory and average polarization theory, the formula of calculating the effective dielectric constant of two-phase random composites with interfacial shells is presented. The theoretical results on effective dielectric constant of alkyd resin paint/Barium titanate random composites with interfacial shells are in good agreement with the experimental data.

NUMERICAL SIMULATION ON TWO-PHASE BUBBLY FLOW SPLIT IN A BRANCHING T-JUNCTION

2011 ◽  
Vol 19 (04) ◽  
pp. 253-262 ◽  
Author(s):  
Y. LIU ◽  
W. Z. LI
Keyword(s):  
Model Simulation ◽  
Bubbly Flow ◽  
Bubble Diameter ◽  
Three Dimensional ◽  
Two Phase ◽  
Flow Parameters ◽  
Two Phases ◽  
Inertia Difference ◽  
Two Fluid ◽  
Good Agreement

In this paper, a steady three-dimensional two-fluid computational fluid dynamics predictive model is presented to simulate the dispersed bubbly flow split phenomenon in a T-junction with 50 mm diameter for all arms. The fluid is treated as a mixture and the fundamental mass, momentum and turbulent equations are solved to account for the flow parameters, where the turbulence is modeled by the standard k − ε model. Simulation results imply that the gas phase inclines to flow into the side arm even for small extraction rate conditions, because the pressure difference of the side arm to inlet is much larger than that of run arm to inlet. The analysis of velocity field reveals that it is the inertia difference between the two phases that leads to the phase split phenomenon. The effect of bubble diameter on flow split is also investigated and it is found that split efficiency is greatly influenced by it. The computed solutions are compared with experimental data and a good agreement is achieved.

Pressure Drop in Circular Two-Phase Pipe Flow As Influenced by the Angle of Inclination

2019 ◽  
Author(s):  
Bethany Worl ◽  
Samuel Nielson ◽  
Xiuling Wang
Keyword(s):  
Pressure Drop ◽  
Two Phase ◽  
Ansys Fluent ◽  
Pressure Drops ◽  
Horizontal Pipes ◽  
Frictional Pressure Drop ◽  
Flow Through ◽  
Two Phases ◽  
Theoretical Pressure ◽  
Experience Difficulty

Abstract A variety of models exist to describe the frictional pressure drop for two-phase flow in a pipe. These models all are based on assumptions and simplifications of the flow regime and can experience difficulty when modeling flow through non-horizontal pipes due to the buoyant effects as the bubbles grow in size. Using computational fluid dynamics, it is possible to model the interaction between the two phases and determine an expected pressure drop. In order to evaluate the effect of the inclination angle of a channel, a parametric study will be conducted using ANSYS Fluent; these predicted pressure drops will then be compared to those found in literature for validation and then to other theoretical pressure drop calculations. Through this study, the benefits of both the theoretical framework and the numerical simulation will be identified.

Velocity Distributions in Two-Phase Vortex Flow

1968 ◽  
Vol 90 (3) ◽  
pp. 368-372
Author(s):  
J. F. Lafferty ◽  
F. G. Hammitt ◽  
R. Cheesewright
Keyword(s):  
Experimental Data ◽  
Analytical Model ◽  
Vortex Flow ◽  
Single Phase ◽  
Gas Jet ◽  
Two Phase ◽  
Two Phases ◽  
Good Agreement

An analytical model is developed to describe gas-jet driven two-phase vortex flow. Utilizing experimental data, the model is used to calculate the velocity distributions of the two phases within an air-water vortex. The computed velocities are in very good agreement with independent measurements and with trends predicted from other investigations of single-phase vortex flow.

Computer Modeling of a Tire under Cornering Loads

1989 ◽  
Vol 17 (2) ◽  
pp. 86-99 ◽  
Author(s):  
I. Gardner ◽  
M. Theves
Keyword(s):  
Finite Element Analysis ◽  
Geometric Approach ◽  
Lateral Force ◽  
Slip Angle ◽  
Element Analysis ◽  
Pressure Distributions ◽  
Slip Effects ◽  
Improved Accuracy ◽  
Nonlinear Geometric ◽  
Good Agreement

Abstract During a cornering maneuver by a vehicle, high forces are exerted on the tire's footprint and in the contact zone between the tire and the rim. To optimize the design of these components, a method is presented whereby the forces at the tire-rim interface and between the tire and roadway may be predicted using finite element analysis. The cornering tire is modeled quasi-statically using a nonlinear geometric approach, with a lateral force and a slip angle applied to the spindle of the wheel to simulate the cornering loads. These values were obtained experimentally from a force and moment machine. This procedure avoids the need for a costly dynamic analysis. Good agreement was obtained with experimental results for self-aligning torque, giving confidence in the results obtained in the tire footprint and at the rim. The model allows prediction of the geometry and of the pressure distributions in the footprint, since friction and slip effects in this area were considered. The model lends itself to further refinement for improved accuracy and additional applications.

Dynamic Behavior Analysis of the Slider Crank Linkage using ANSYS Workbench and MATLAB Program

2013 ◽  
Vol 1 (1) ◽  
pp. 42-25
Author(s):  
Nabil N. Swadi
Keyword(s):  
Graphical Method ◽  
Joint Torque ◽  
Pressure Force ◽  
Matlab Program ◽  
Element Simulation ◽  
Acceleration Method ◽  
Complete Revolution ◽  
Two Phases ◽  
Good Agreement ◽  
Ansys Workbench

This paper is concerned with the study of the kinematic and kinetic analysis of a slider crank linkage using D'Alembert's principle. The links of the considered mechanism are assumed to be rigid. The analytical solution to observe the motion (displacement, velocity, and acceleration), reactions at each joint, torque required to drive the mechanism and the shaking force have been computed by a computer program written in MATLAB language over one complete revolution of the crank shaft. The results are compared with a finite element simulation carried out by using ANSYS Workbench software and are found to be in good agreement. A graphical method (relative velocity and acceleration method) has been also applied for two phases of the crank shaft (q2 = 10° and 130°). The results obtained from this method (graphical) are compared with those obtained from analytical and numerical method and are found very acceptable. To make the analysis linear the friction force on the joints and sliding interface are neglected. All results, in this work, are obtained when the crank shaft turns at a uniform angular velocity (w2 = 188.5 rad/s) and time dependent gas pressure force on the slider crown.

Numerical Modeling of Evolution of Boundary Between Incompressible Gas and Liquid in Two-Dimensional Region

2006 ◽  
Vol 4 ◽  
pp. 224-236
Author(s):  
A.S. Topolnikov
Keyword(s):  
Numerical Modeling ◽  
Interphase Boundary ◽  
Incompressible Liquid ◽  
Stokes Equations ◽  
Numerical Code ◽  
Navier Stokes ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Incompressible Media ◽  
Good Agreement

The paper is devoted to numerical modeling of Navier–Stokes equations for incompressible media in the case, when there exist gas and liquid inside the rectangular calculation region, which are separated by interphase boundary. The set of equations for incompressible liquid accounting for viscous, gravitational and surface (capillary) forces is solved by finite-difference scheme on the spaced grid, for description of interphase boundary the ideology of Level Set Method is used. By developed numerical code the set of hydrodynamic problems is solved, which describe the motion of two-phase incompressible media with interphase boundary. As a result of numerical simulation the solutions are obtained, which are in good agreement with existing analytical and experimental solutions.

The effect of two-phase flow regime on hydrodynamics and mass transfer in a horizontal-tube gas-liquid reactor

1985 ◽  
Vol 50 (3) ◽  
pp. 745-757 ◽  
Author(s):  
Andreas Zahn ◽  
Lothar Ebner ◽  
Kurt Winkler ◽  
Jan Kratochvíl ◽  
Jindřich Zahradník
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Flow Regime ◽  
Liquid Flow ◽  
Horizontal Tube ◽  
Liquid Holdup ◽  
Two Phase ◽  
Flow Rates ◽  
Type Relation ◽  
Good Agreement

The effect of two-phase flow regime on decisive hydrodynamic and mass transfer characteristics of horizontal-tube gas-liquid reactors (pressure drop, liquid holdup, kLaL) was determined in a cocurrent-flow experimental unit of the length 4.15 m and diameter 0.05 m with air-water system. An adjustable-height weir was installed in the separation chamber at the reactor outlet to simulate the effect of internal baffles on reactor hydrodynamics. Flow regime maps were developed in the whole range of experimental gas and liquid flow rates both for the weirless arrangement and for the weir height 0.05 m, the former being in good agreement with flow-pattern boundaries presented by Mandhane. In the whole range of experi-mental conditions pressure drop data could be well correlated as a function of gas and liquid flow rates by an empirical exponential-type relation with specific sets of coefficients obtained for individual flow regimes from experimental data. Good agreement was observed between values of pressure drop obtained for weirless arrangement and data calculated from the Lockhart-Martinelli correlation while the contribution of weir to the overall pressure drop was well described by a relation proposed for the pressure loss in closed-end tubes. In the region of negligible weir influence values of liquid holdup were again succesfully correlated by the Lockhart-Martinelli relation while the dependence of liquid holdup data on gas and liquid flow rates obtained under conditions of significant weir effect (i.e. at low flow rates of both phases) could be well described by an empirical exponential-type relation. Results of preliminary kLaL measurements confirmed the decisive effect of the rate of energy dissipation on the intensity of interfacial mass transfer in gas-liquid dispersions.

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