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121 
Pressure Drop Across a Restriction of Annular GeometryYarizadeh, Farshid 01 January 1982 (has links) (PDF)
This report presents experimental results for the pressure drop across a restriction of annular geometry used in a typical pressurized water reactor steam generator. The pressure drops were obtained for air, water, and the corresponding twophase mixtures.
The loss coefficients associated with these pressure drops were experimentally determined and empirical relations correlating the results were developed.
The tests were performed at atmospheric conditions (atmospheric temperature and pressure), and the twophase flow mass velocity ranged from 236 to 711 1bm/sft2.

122 
Pressure Drop Across a Tube Support Plate of Trefoil Geometry Used in Steam GeneratorBashar, Raad H. 01 July 1983 (has links) (PDF)
This research is concerned with the presentation of pressure drop experimental results across a restriction of trefoil geometry (tube support plate) used in steam generators. The pressure drops were obtained for singlephase and twophase of air, water, and their mixtures. The tests were performed at atmospheric conditions (pressure and temperature). The loss coefficients associated with these pressure drops were experimentally determined, and empirical correlations for the results were developed. The results were compared with previous studies done on other geometries with airwater mixtures, and also to a similar geometry with steamwater mixture.

123 
A Computational Model to Estimate the Thickness of the Waterfilm Due to Rain on the Upper Surface of an AirfoilChappidi, Padmanabha R. 01 January 1985 (has links) (PDF)
Based on a twophase boundary layer approach, a computational model is proposed to estimate the thickness of the waterfilm due to rain on the upper surface of an airfoil. The coupling between the air boundary layer and the water film is established by the conservation of mass and momentum at the interface. By a simple coordinate transformation, the interface is conformed to the finite difference grid system. Trajectory analysis of a raindrop of 1 mm diameter shows that the impingement of drops is high near the leading edge of the airfoil and decreases downstream. The finite difference equations of air/waterfilm are based on a Crank Nicholson scheme. The solution of finite difference equations at the initial station indicates a film thickness of 0.01 mm. Marching downstream along the surface of the airfoil gives raise to stability problems in the finite difference equations.

124 
The Study of Flooding Correlations of CounterCurrent TwoPhase Flow in a Vertical Tube under Electric FieldRevankar, S. T. January 1982 (has links)
A countercurrent twophase flow under an applied electric field has been studied theoretically using potential flow equations. A flooding correlation has been derived taking account of applied electric field on the interface for both adiabatic and condensing system. It is found that the electric field enhances flooding phenomena in case of adiabatic system. In the case with system involving condensation the electric field enhances flooding at low liquid flow rates and at high liquid flow rates the flooding point decreases under electric field depending on the rate of subcooling. / Thesis / Master of Engineering (ME)

125 
Extension of the finite volume method to laminar and turbulent flowNicholson, Stephen January 1986 (has links)
A method has been developed which calculates twodimensional, transonic, viscous flow in ducts. The finite volume, time marching formulation is used to obtain steady flow solutions of the Reynoldsaveraged form of the Navier Stokes equations. The entire calculation is performed in the physical domain. The method is currently limited to the calculation of attached flows.
The features of the current method can be summarized as follows. Control volumes are chosen so that smoothing of flow properties, typically required for stability, is not needed. Different time steps are used in the different governing equations to improve the convergence speed of the viscous calculations. A new pressure interpolation scheme is introduced which improves the shock capturing ability of the method. A multivolume method for pressure changes in the boundary layer allows calculations which use very long and thin control volumes (length/height ≅ 1000). A special discretization technique is also used to stabilize these calculations which use long and thin control volumes. A special formulation of the energy equation is used to provide improved transient behavior of solutions which use the full energy equation.
The method is then compared with a wide variety of test cases. The freestream Mach numbers range from 0.075 to 2.8 in the calculations. Transonic viscous flow in a converging diverging nozzle is calculated with the method; the Mach number upstream of the shock is approximately 1.25. The agreement between the calculated and measured shock strength and total pressure losses is good. Essentially incompressible turbulent boundary layer flow in an adverse pressure gradient is calculated and the computed distribution of mean velocity and shear stress are in good agreement with the measurements. At the other end of the Mach number range, a flat plate turbulent boundary layer with a freestream Mach number of 2.8 is calculated using the full energy equation; the computed total temperature distribution and recovery factor agree well with the measurements when a variable Prandtl number is used through the boundary layer. / Ph. D.

126 
An integral analysis of twophase annularmist condensing flowsBerry, Maurice Robert 12 June 2010 (has links)
In this investigation of the twophase, annularmist flow of a condensing vapor, the following significant conclusions are drawn. The conclusions are based on the numerical results obtained from the theoretical analysis. Where appropriate, recommendations for future studies are included:
1. The analytical model accurately predicts the condenser length necessary for complete condensation and, with a reasonable degree of accuracy, the dynamic quality, heat transfer characteristics, and static pressure distribution.
2. An integral analysis is presented for which the assumed velocity and enthalpy profiles are the powerlaw type. For the range of temperatures and pressures encountered in this investigation, varying the profile shapes has a negligible effect on the dynamic quality and static pressure distributions at all except high vapor velocities.
3. The analysis accounts for the slip between the entrained particles and the vapor in the gas core. A constant entrainment slip ratio (SE) is assumed. Reducing the ratio below unity has an effect of the static pressure drop. The effect, however, is comparatively small.
4. Due to the lack of entrainment flow rate data available for twophase, annularmist, condensing flows, a variable entrainment correlation is included in the analysis. / Ph. D.

127 
The experimental and numerical approach of twophase flows by wall jets on rough beds in open channel flowGhoma, Mohamed Ibrahem, Hussain, Khalid, Tait, Simon J. January 2014 (has links)
Yes / This paper presents the results of investigations
carried out to study the effect of horizontal wall jets on a fixed
rough bed in an open channel. The study used both numerical
and experimental approaches. The numerical and experimental
studies are compared for validation. The main objective of this
study is to understand the effect of wall jets on a horizontal
fixed rough bed in an open channel.
The experimental study investigated the effect of wall jets on
a fixed horizontal bed, with a known roughness in an open
channel flume. A sidlooking Acoustic Doppler Velocimetry
(ADV) was used to measure the velocity profile of the flow at
different flow zones. The wave monitor was used to measure the
free surface during the experiments.
Computational fluid dynamics CFD simulations were
conducted in a rectangular channel to compare with the
laboratory tests using the volume of fluid VOF multiphase
method and K ࢿ model. The two phase (water and air) was
used in this study. Computer simulations for the model were
used to predict the fluid horizontal velocity (u) revealing the
characteristics of the wall jet over different flow zones
(developing, fully developed and recovering zones).
The results showed that the velocity profiles distribution in
the stream wise direction in the channel were reasonable. The
reverse velocity was close to the wall jet and the maximum
reverse velocity was observed near the water surface. Also the
results showed that the depression was close to the wall jet.
The agreement between the results obtained from the
numerical and the experimental data were reasonable.

128 
Spatiotemporal Characteristics of a Spray from a Liquid Jet in CrossflowThawley, Scott 23 March 2006 (has links)
A liquid jet in a crossflow is often used to as a fuel injection method for combustion systems. Parameters such as penetration and core trajectory are used as characterization for the spray and specification of design criteria for combustor geometry. In addition to penetration and core trajectory, mapping the mass flux in space and time is an important part of modeling evaporation and global equivalence ratio throughout the combustor. Accurate prediction of these spray characteristics allows for a stable and robust combustor design.
The break up of a liquid jet in a crossflow is an extremely complex phenomenon in both combination of mechanisms and variability of possible paths progressing from a liquid column to a distribution of individual droplets. In each region separate governing forces control the behavior of the liquid phase. Accordingly, different measurement techniques and different factors must be considered in each region.
Presented are the results of measurements using Phase Doppler Analyzer, PDA, and a time resolved, digital, particle imaging velocimetry system, TRDPIV. The measurements include instantaneous and timeaveraged liquid phase velocity fields, spray penetration and core location in the near field and far field of the spray resulting from the liquid jet breakup.
With the TRDPIV system, the holistic properties of all three segments of a jet in crossflow were acquired with a single measurement. This allowed for comparison of system characteristics across not only individual pieces of one segment of the jet, for example PDA measurements of many droplets in one point of the far field spray, but characteristics across the entire system including the liquid column, near field spray, and far field spray simultaneously in a fashion that allowed for direct comparison between the different segments. / Master of Science

129 
Subgrid Combustion Modeling for Compressible TwoPhase FlowsSankaran, Vaidyanathan 24 November 2003 (has links)
A generic formulation for modeling the subgrid combustion in
compressible, high Reynolds number, twophase, reacting flows has
been developed and validated. A subgrid mixing/combustion model
called Linear Eddy Mixing (LEM) model has been extended to
compressible flows and used inside the framework of Large Eddy
Simulation (LES) in this LESLEM approach. The LESLEM approach is
based on the proposition that the basic mechanistic distinction
between the convective and the molecular effects should be
preserved for accurate prediction of the complex flowfields such
as those encountered in many combustion systems. In LESLEM, all
the physical processes such as molecular diffusion, small and
large scale turbulent convection and chemical reaction are modeled
separately but concurrently at their respective time scales. This
multiscale phenomena is solved using a twoscale numerical
approach, wherein molecular diffusion, small scale turbulent
convection and chemical reaction are grouped as small scale
processes and the convection at the (LES grid) resolved scales are
deemed as the large scale processes. Smallscale processes are
solved using a hybrid finitedifference Montecarlo type approach
in a onedimensional domain. Largescale advection on the
threedimensional LES grid is modeled in a Lagrangian manner that
conserves mass.
Liquid droplets (represented by computational parcels) are tracked
using the Lagrangian approach wherein the Newton's equation of
motion for the discrete particles are integrated explicitly in the
Eulerian gas field.
Drag effects due to the droplets on the gas phase and the heat
transfer between the gas and the liquid phase are explicitly
included. Thus, full coupling is achieved between the two phases
in the simulation.
Validation of the compressible LESLEM approach is conducted by
simulating the flowfield in an operational General Electric
Power Systems' combustor (LM6000). The results predicted using
the proposed approach compares well with the experiments and a
conventional (Gequation) thinflame model.
Particle tracking algorithms used in the present study are
validated by simulating droplet laden temporal mixing layers.
Comparison of the energy growth in the fundamental and
subharmonic mode in the presence and absence of the droplets
shows excellent agreement with spectral DNS.
Finally, to test the ability of the present twophase LESLEM in
simulating partially premixed combustion, a LES of freely
propagating partially premixed flame in a dropletladen isotropic
turbulent field is conducted. LESLEM along with the spray models
correctly captures the flame structure in the partially premixed
flames. It was found that most of the fuel droplets completely
vaporize before reaching the flame, and hence provides a
continuous supply of reactants, which results in an intense
reaction zone similar to a premixed flame. Some of the droplets
that did not evaporate completely, traverse through the flame and
vaporize suddenly in the post flame zone. Due to the strong
spatial variation of equivalence ratio a broad flame similar to a
premixed flame is realized. Triple flame structure are also
observed in the flowfield due to the equivalence ratio
fluctuations.

130 
Studies of Horizontal TwoPhase Flow Using Electrical Capacitance Tomography and R134aRoman, Abdeel J. 20 December 2017 (has links)
No description available.

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