Computation of Annular, Turbulent Flow With Rotating Core Tube

1976 ◽  
Vol 98 (4) ◽  
pp. 753-758 ◽  
Author(s):  
B. I. Sharma ◽  
B. E. Launder ◽  
C. J. Scott
Keyword(s):  
Experimental Data ◽  
Turbulent Flow ◽  
Transport Model ◽  
Rotational Velocity ◽  
Numerical Procedure ◽  
Mean Flow ◽  
Core Tube ◽  
The Core ◽  
Numerical Predictions ◽  
Bulk Flow Rate

Numerical predictions are presented of fully-developed turbulent flow through a concentric annulus in which the core tube rotates about its axis. Comparisons are drawn with the extensive experimental data of Kuzay and Scott [1] which span Reynolds numbers from 1.7 to 104 to 6.5 × 104 and with rotational speeds of the core tube varying from zero to nearly 2.8 times the bulk axial velocity. Predictions have been obtained by means of an adapted version of the Patankar-Spalding [5], numerical procedure employing, as turbulent transport model, the version of the mixing length hypothesis applied by Koosinlin, Sharma and Launder [2] to flows on spinning cones and cylinders. Agreement with experiment is generally close at the higher relative swirl rates but the predictions of the swirling velocity profile deteriorate as the bulk flow rate is increased. The discrepancy seems to be due to the experimental data requiring a greater development length as the magnitude of the rotational velocity is reduced relative to that of the mean flow. Demonstrative developing-flow predictions are provided which exhibit closer agreement with the experimental data.

Numerical Prediction of Flow in a Nuclear Fuel Bundle With Various Turbulence Models

2002 ◽  
Author(s):  
Wang Kee In ◽  
Dong Seok Oh ◽  
Tae Hyun Chun
Keyword(s):  
Turbulent Flow ◽  
Nuclear Fuel ◽  
Turbulence Models ◽  
Convective Transport ◽  
Stress Model ◽  
Convergence Criteria ◽  
Mean Flow ◽  
Numerical Predictions ◽  
Viscosity Models ◽  
Fuel Bundle

The numerical predictions using the standard and RNG k–ε eddy viscosity models, differential stress model (DSM) and algebraic stress model (ASM) are examined for the turbulent flow in a nuclear fuel bundle with the mixing vane. The hybrid (first-order) and curvature-compensated convective transport (CCCT) schemes were used to examine the effect of the differencing scheme for the convection term. The CCCT scheme was found to more accurately predict the characteristics of turbulent flow in the fuel bundle. There is a negligible difference in the prediction performance between the standard and RNG k-ε models. The calculation using ASM failed in meeting the convergence criteria. DSM appeared to more accurately predict the mean flow velocities as well as the turbulence parameters.

Prediction of Cavitation Inception Within Regions of Flow Separation

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Eduard Amromin
Keyword(s):  
Experimental Data ◽  
Turbulent Flow ◽  
Flow Separation ◽  
Computational Method ◽  
Average Flow ◽  
Cavitation Inception ◽  
The Core ◽  
Good Agreement

Cavitation within regions of flow separation appears in drifting vortices. A two-part computational method is employed for prediction of cavitation inception number there. The first part is an analysis of the average flow in separation regions without consideration of an impact of vortices. The second part is an analysis of equilibrium of the bubble within the core of a vortex located in the turbulent flow of known average characteristics. Computed cavitation inception numbers for axisymmetric flows are in the good agreement with the known experimental data.

A vortex-street model of the flow in the similarity region of a two-dimensional free turbulent jet

1982 ◽  
Vol 123 ◽  
pp. 523-535 ◽  
Author(s):  
J. W. Oler ◽  
V. W. Goldschmidt
Keyword(s):  
Experimental Data ◽  
Reynolds Stress ◽  
Turbulent Jet ◽  
Vortex Street ◽  
Two Dimensional ◽  
Mean Flow ◽  
Mean Velocity ◽  
The Core ◽  
The Mean ◽  
Similarity Relationships

The mean-velocity profiles and entrainment rates in the similarity region of a two-dimensional jet are generated by a simple superposition of Rankine vortices arranged to represent a vortex street. The spacings between the vortex centres, their two-dimensional offsets from the centreline, as well as the core radii and circulation strengths, are all governed by similarity relationships and based upon experimental data.Major details of the mean flow field such as the axial and lateral mean-velocity components and the magnitude of the Reynolds stress are properly determined by the model. The sign of the Reynolds stress is, however, not properly predicted.

A Viscous-Inviscid Interaction Procedure—Part 2: Application to Turbulent Flow Over a Rearward-Facing Step

1986 ◽  
Vol 108 (1) ◽  
pp. 71-75 ◽  
Author(s):  
O. K. Kwon ◽  
R. H. Pletcher
Keyword(s):  
Turbulent Flow ◽  
Turbulence Modeling ◽  
Numerical Procedure ◽  
Length Scale ◽  
Two Dimensional ◽  
Reattachment Length ◽  
Mean Flow ◽  
Channel Expansion ◽  
Good Agreement

The viscous-inviscid interaction numerical procedure described in Part 1 is used to predict steady, two-dimensional turbulent flow over a rearward-facing step. The accuracy of predictions is observed to be quite sensitive to the specification of length scale in the turbulence modeling. The best results are observed when the length scale is specified algebraically downstream of the step using parameters characteristic of the step geometry. Predictions of mean flow quantities and reattachment length are shown to be in generally good agreement with measurements obtained over a range of channel expansion ratios.

Turbulent Flow in an Annulus

1967 ◽  
Vol 89 (1) ◽  
pp. 25-31 ◽  
Author(s):  
S. Levy
Keyword(s):  
Turbulent Flow ◽  
Tube Wall ◽  
Eddy Diffusivity ◽  
Test Results ◽  
Core Tube ◽  
The Core ◽  
Roughened Surface ◽  
Shear Mixing ◽  
Fully Developed Turbulent Flow ◽  
Good Agreement

Equations describing fully developed turbulent flow in an annulus are derived. They are based upon Reichardt’s expression for the eddy diffusivity of momentum, and they assume that the velocity profiles starting from the core tube wall and the outer tube wall have the same velocity and eddy diffusivity at the plane of zero shear. The predicted location of the plane of zero shear, mixing length, eddy diffusivity, velocity distribution, and friction factor are compared to available data and are found to give good agreement with the test results. Potential extension of the proposed method to more complex geometries is illustrated by considering the case of flow in an annulus with one artificially roughened surface.

scholarly journals Turbulent flow dynamics and mass transport processes in a natural surface storage zone using field data and numerical simulations

2018 ◽  
Vol 40 ◽  
pp. 05064 ◽  
Author(s):  
Jorge Sandoval ◽  
Cristián Escauriaza ◽  
Emmanuel Mignot ◽  
Luca Mao
Keyword(s):  
Mass Transport ◽  
Turbulent Flow ◽  
Numerical Simulations ◽  
Field Data ◽  
Large Scale ◽  
Transport Model ◽  
Transport Processes ◽  
Flow Dynamics ◽  
Surface Velocity ◽  
Mean Flow

In this work, the turbulent flow dynamics and mass transport mechanisms in a natural SSZis analyzed. The study site is a river reach of the Lluta River, located in northern Chile in a high-altitude Andean environment known as the Altiplano (~ 4,000 masl) The large-scale turbulent coherent structures are characterized using field measurements and 3D numerical simulations. The detailed topography was measured through DGPS and digital image processing while the surface velocity field, through the LSPIV technique. Regarding the field data, numerical simulations were performed using a DES turbulence model coupled with a 3D passive scalar transport model for Re = 45,800. The coherent structure dynamics in the shear layer was identified as the main mechanism that drives the mass and momentum transport processes between the SSZ and the main channel. Also, the 2D vortical structures of the mean flow are analyzed within the lateral cavity, since they have a strong influence in mass transport, increasing mean residence times due to their lower velocities and longer exchange timescales. Finally, the performance of two simplified transport models is analyzed to represent the mass transport dynamics at larger scales.

Numerical Predictions for the Flow Induced by an Enclosed Rotating Disc

1988 ◽  
Author(s):  
John W. Chew ◽  
Craig M. Vaughan
Keyword(s):  
Experimental Data ◽  
Reasonable Agreement ◽  
Mixing Length ◽  
Mean Flow ◽  
Rotating Disc ◽  
Numerical Predictions ◽  
Stationary Disc ◽  
The Mean ◽  
Radial Outflow ◽  
Good Agreement

Finite difference solutions are presented for turbulent flow in the cavity formed between a rotating and a stationary disc, with and without a net radial outflow of fluid. The mean flow is assumed steady and axisymmetric and a mixing length model of turbulence is used. Grid dependency of the solutions is shown to be acceptably small and results are compared with other workers’ experimental data. Theoretical and measured disc moment coefficients are in good agreement, while theoretical and measured velocities are in reasonable agreement. It is concluded that the mixing-length model is sufficiently accurate for many engineering calculations of boundary layer dominated flows in rotating disc systems.

scholarly journals Turbulent Flow in a Micro-Channel

2006 ◽  
Author(s):  
Tomasz A. Kowalewski ◽  
Slawomir Blonski ◽  
Piotr M. Korczyk
Keyword(s):  
Experimental Data ◽  
Energy Dissipation ◽  
Turbulent Flow ◽  
High Speed ◽  
Pure Water ◽  
Nano Particles ◽  
Flow Measurements ◽  
Micro Particle Image Velocimetry ◽  
Micro Piv ◽  
Numerical Predictions

Turbulent flow of water in a narrow gap of an emulsifier is investigated experimentally using micro-PIV (micro Particle Image Velocimetry) technique and compared with numerical predictions performed using the commercial code Fluent. The purpose of the investigations is to develop a procedure for well-controlled generation of mono-disperse suspension of micro droplets. These droplets will form a matrix for collection of nano-particles into well-structured configuration [1]. The micro-flow measurements are based on epi-fluorescence illumination and high-speed imaging. The experimental data are compared with the numerical results obtained using both turbulent and laminar flow models. It was found that, due to small channel dimensions and very small flow development length, the turbulent energy dissipation takes place mainly in the gap and shortly behind it. Very low amount of oil-phase fraction in investigated emulsions justifies us to use mean energy dissipation estimated for pure water to predict mean diameter of oil droplets. These predictions are validated using experimental data for the emulsion.

The Numerical Prediction of Developing Turbulent Flow in Rectangular Ducts

1981 ◽  
Vol 103 (3) ◽  
pp. 445-453 ◽  
Author(s):  
F. B. Gessner ◽  
A. F. Emery
Keyword(s):  
Experimental Data ◽  
Turbulent Flow ◽  
Three Dimensional ◽  
Computational Procedure ◽  
Momentum Equation ◽  
Scale Model ◽  
Length Scale ◽  
Basic Technique ◽  
Numerical Predictions ◽  
Iterative Procedures

Comparisons are made between experimental data and numerical predictions based on a three-dimensional length-scale model applicable to developing turbulent flow in rectangular ducts of arbitrary aspect ratio. The numerical method utilizes an explicit (Dufort-Frankel) differencing scheme for the axial momentum equation and involves no iterative procedures. Although the basic technique has been applied previously to another class of three-dimensional flows, it has not been applied until now to slender shear flows dominated by secondary flow of the second kind. The merits of the length-scale model and the computational procedure are assessed by means of comparisons with results referred to both k–ε and full Reynolds stress closure models which have been applied in recent years.

Numerical Simulation of Different Types of Steam Surface Condensers

1991 ◽  
Vol 113 (2) ◽  
pp. 63-70 ◽  
Author(s):  
C. Zhang ◽  
A. C. M. Sousa ◽  
J. E. S. Venart
Keyword(s):  
Experimental Data ◽  
Control Volume ◽  
Numerical Procedure ◽  
Governing Equations ◽  
Transfer Processes ◽  
Flow And Heat Transfer ◽  
Numerical Predictions ◽  
Surface Condenser ◽  
Different Types ◽  
Good Agreement

A numerical procedure is developed to simulate the fluid flow and heat transfer processes in the shell-side of steam surface condensers. The governing equations are solved in primitive variable form using a semi-implicit consistent control-volume formulation in which a segregated pressure correction linked algorithm is employed. The procedure is applied to three different types of surface condenser. The numerical predictions are critically assessed by comparison to available experimental data for condensers, and in general, the solutions are in good agreement with the experimental data.

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