The decay of a turbulent swirl in a pipe

1965 ◽  
Vol 22 (2) ◽  
pp. 257-271 ◽  
Author(s):  
Frank Kreith ◽  
O. K. Sonju
Keyword(s):  
Experimental Data ◽  
Eddy Diffusivity ◽  
Reynolds Numbers ◽  
Experimental Measurements ◽  
Number Range ◽  
Swirl Velocity ◽  
Linearized Theory ◽  
Flow Through ◽  
Initial Intensity ◽  
Good Agreement

This paper presents a linearized theory for the average decay of a tape-induced fully developed turbulent swirl in flow through a pipe. In the Reynolds number range between 104 and 105 the theoretical analysis was found to be in good agreement with experimental data obtained with water in a 1 in. pipe, provided the eddy diffusivity was chosen appropriately.It was observed that a turbulent swirl decays to about 10–20% of its initial intensity in a distance of about 50 pipe diameters, the decay being more rapid at smaller than at larger Reynolds numbers. The theoretical swirl velocity distribution agreed qualitatively with experimental measurements at distances less than 20 diameters downstream from the outlet of the swirl inducer, but deviated from the experimental results further downstream.

Forced Convection in a Porous Channel With Discrete Heat Sources

2000 ◽  
Vol 123 (2) ◽  
pp. 404-407 ◽  
Author(s):  
C. Cui ◽  
X. Y. Huang ◽  
C. Y. Liu
Keyword(s):  
Heat Transfer ◽  
Reynolds Numbers ◽  
Heat Fluxes ◽  
Experimental Results ◽  
Porous Channel ◽  
Heat Sources ◽  
Nusselt Numbers ◽  
Discrete Heat Sources ◽  
Flow Through ◽  
Good Agreement

An experimental study was conducted on the heat transfer characteristics of flow through a porous channel with discrete heat sources on the upper wall. The temperatures along the heated channel wall were measured with different heat fluxes and the local Nusselt numbers were calculated at the different Reynolds numbers. The temperature distribution of the fluid inside the channel was also measured at several points. The experimental results were compared with that predicted by an analytical model using the Green’s integral over the discrete sources, and a good agreement between the two was obtained. The experimental results confirmed that the heat transfer would be more significant at leading edges of the strip heaters and at higher Reynolds numbers.

A Continuous Prediction Method for Fully Developed Laminar, Transitional, and Turbulent Flows in Pipes

1975 ◽  
Vol 42 (1) ◽  
pp. 51-54 ◽  
Author(s):  
N. W. Wilson ◽  
R. S. Azad
Keyword(s):  
Turbulent Flows ◽  
Flow Characteristics ◽  
Prediction Method ◽  
Reynolds Numbers ◽  
Mean Flow ◽  
Number Range ◽  
Circular Pipes ◽  
The Mean ◽  
Single Set ◽  
Good Agreement

A single set of equations is developed to predict the mean flow characteristics in long circular pipes operating at laminar, transitional, and turbulent Reynolds numbers. Generally good agreement is obtained with available data in the Reynolds number range 100 < Re < 500,000.

LP Turbine Reynolds Lapse Phenomena: Time Averaged Area Traverse and Multistage CFD

2010 ◽  
Author(s):  
Matthias Ku¨rner ◽  
Carsten Schneider ◽  
Martin G. Rose ◽  
Stephan Staudacher ◽  
Jochen Gier
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Reynolds Numbers ◽  
Test Rig ◽  
Propulsion Systems ◽  
Number Range ◽  
Second Stage ◽  
Number Variation ◽  
Aero Engines ◽  
Lp Turbine

The new LP turbine test rig “ATRD” at the Institute of Aircraft Propulsion Systems (ILA) at Stuttgart University has been used to study the detailed effects of Reynolds number variation. The two-stage LP turbine has been developed in a cooperation of ILA and MTU Aero Engines GmbH. Changes in the turbine characteristics are discussed. Five hole probe area traverse data has been acquired at exit from each row of aerofoils across a broad range of Reynolds numbers, over 88,000 down to 35,000. The experimental data is supported by multi-row steady CFD predictions. The behaviour of wakes, loss cores and secondary deviations is identified across the Reynolds number range. The present study is focusing on the effects of Reynolds number variation on the vane of the second stage.

On the Comparison Between Lubrication Theory, Including Turbulence and Inertia Forces, and Some Existing Experimental Data

1975 ◽  
Vol 97 (3) ◽  
pp. 439-448 ◽  
Author(s):  
V. N. Constantinescu ◽  
S. Galetuse ◽  
F. Kennedy
Keyword(s):  
Experimental Data ◽  
Thin Films ◽  
Reynolds Numbers ◽  
Lubrication Theory ◽  
Incoming Flow ◽  
Flow Conditions ◽  
Film Rupture ◽  
Inertia Forces ◽  
Proper Consideration ◽  
Good Agreement

The results obtained by using lubrication theory, including inertia forces, are checked against experimental data concerning flows in relatively thin films at moderate and large Reynolds numbers. It is shown that a reasonably good agreement is obtained provided that the peculiar features of the experimental flow are properly taken into account; namely, proper consideration of the type of flow (laminar, transition, turbulent), proper evaluation of the region where lubrication flow prevails, entrance flow conditions (relating the flow into the film to the incoming flow), conditions for film rupture, cavitation or separation.

Analysis of Heat Transfer and Fluid Flow Through a Spirally Fluted Tube Using a Porous Substrate Approach

1994 ◽  
Vol 116 (3) ◽  
pp. 543-551 ◽  
Author(s):  
Vijayaragham Srinivasan ◽  
Kambiz Vafai ◽  
Richard N. Christensen
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Porous Substrate ◽  
The Finite Element Method ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Numerical Predictions ◽  
Friction Factors ◽  
Flow Through ◽  
Good Agreement

An innovative approach was opted for modeling the flow and heat transfer through spirally fluted tubes. The model divided the flow domain into two regions. The flutes were modeled as a porous substrate with direction-dependent permeabilities. This enabled modeling the swirl component in the fluted tube. The properties of the porous substrate such as its thickness, porosity, and ratio of the direction-dependent permeabilities were obtained from the geometry of the fluted tube. Experimental data on laminar Nusselt numbers and friction factors for different types of fluted tubes representing a broad range of flute geometry were available. Experimental data from a few of the tubes tested were used to propose a relationship between the permeability of the porous substrate and the flute parameters, particularly the flute spacing. The governing equations were discretized using the Finite Element Method. The model was verified and applied to the other tubes in the test matrix. Very good agreement was found between the numerical predictions and the experimental data.

scholarly journals Influence of fin thickness on heat transfer and flow performance of a parallel flow evaporator

2019 ◽  
Vol 23 (4) ◽  
pp. 2413-2419 ◽  
Author(s):  
Haijun Li ◽  
Enhai Liu ◽  
Guanghui Zhou ◽  
Fengye Yang ◽  
Zhiyong Su ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Comprehensive Evaluation ◽  
Reynolds Numbers ◽  
Parallel Flow ◽  
Heat Transfer Factor ◽  
Heat Transfer Capacity ◽  
Fin Thickness ◽  
The Heat Transfer Coefficient ◽  
Good Agreement

This paper studies numerically the influence of the louver?s fin thickness on heat transfer and flow performance of a parallel flow evaporator, a comprehensive evaluation and analysis of the five structures at different Reynolds numbers are systematically carried out. Comparison of the numerical results with the experimental data shows good agreement with maximal errors of 12.16% and 5.29% for the heat transfer factor and the resistance factor, respectively. The results show that the heat transfer coefficient and the pressure drop increase with the increase of the thickness of the louver fins when the Reynolds number is a constant. The analysis of the comprehensive evaluation factor shows that the A-type fin is the best, and it can effectively strengthen the heat exchange on the air side and improve the heat transfer capacity of the system. The research results can provide reference for the structural optimization of the louver fins.

Heat Transfer in Two-Dimensional Turbulent Confined Flows

1972 ◽  
Vol 186 (1) ◽  
pp. 625-633
Author(s):  
A. P. Hatton ◽  
N. H. Woolley
Keyword(s):  
Prediction Method ◽  
Eddy Diffusivity ◽  
Reynolds Numbers ◽  
Turbulence Energy ◽  
Two Dimensional ◽  
Narrow Angle ◽  
Before And After ◽  
Dimensional Equation ◽  
Confined Flows ◽  
Good Agreement

Measurements of displacement and momentum thickness, friction factor and Stanton number were made in a narrow angle diverging duct consisting of two plane walls, width 0·82 m. The height of the duct varied from 0·051 to 0·152 m over a length of 3·94 m. Reynolds numbers ranged from 8·7 × 104 to 20·7 × 104. The results are compared with a prediction method using a numerical solution of the two-dimensional equation of motion and energy. An eddy diffusivity hypothesis was used, based on the turbulence energy equation and an empirical length scale distribution. Good agreement was obtained between the theoretical and experimental results, both before and after the boundary layers interfered, and with previously reported experiments in a parallel duct. It was necessary to change the value of one of the constants in the analysis for each geometry.

A Theory of Sharp-Edged Orifices

1937 ◽  
Vol 4 (2) ◽  
pp. A53-A54
Author(s):  
W. E. Howland
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Discharge Coefficient ◽  
Reynolds Numbers ◽  
Experimental Results ◽  
Low Reynolds Numbers ◽  
Circular Orifice ◽  
Coefficient Of Discharge ◽  
Theoretical Considerations ◽  
Good Agreement

Abstract The author presents a figure in which the coefficient of discharge Cd, velocity Cv, and contraction Cc determined by several investigators are plotted logarithmically as points against Reynolds’ numbers. Curves for the coefficients drawn by the author, based on theoretical considerations, show good agreement with the experimental data, thus throwing some light upon the basic phenomena of the discharge of sharp-edged orifices. The variation of the coefficient of discharge of a circular orifice as a function of the Reynolds number is explained as a purely viscous phenomenon for low Reynolds numbers, and by means of a momentum analysis for higher speeds. The analysis presented by the author leads to the development of several formulas for the discharge coefficient, which formulas are in fair agreement with experimental results.

Model Testing and CFD Analysis of 2D Profiles Towards Offshore Applications

2013 ◽  
Author(s):  
Lucas do Vale Machado ◽  
Antonio Carlos Fernandes ◽  
Gustavo César Rachid Bodstein
Keyword(s):  
Experimental Data ◽  
Experimental Measurements ◽  
Cfd Analysis ◽  
Two Dimensional ◽  
Reference Simulation ◽  
Sst Turbulence Model ◽  
Computational Fluid Dynamics Cfd ◽  
Simulation Results ◽  
Naca 0015 ◽  
Good Agreement

In this paper we present numerical and experimental work motivated by the study of a rudder profile with significant levels of lift that provides better performance for the maneuvering and stabilization of a ship. This is the so-called Schilling profile. The analysis of the two-dimensional subsonic steady flow over four profiles was carried out using computational fluid dynamics (CFD) tools with a κ-ω SST turbulence model. We consider three Schilling profiles with different thicknesses and the classical NACA 0015 profile, taken as a reference. Simulation results were compared to our experimental measurements at various angles of attack and two orders of magnitude of the Reynolds number, 5.45 × 104 and 1.09 × 105. The numerical results show general good agreement with experimental data and highlight the distinct behavior of Schilling profile.

Steady two-dimensional flow through a row of normal flat plates

1990 ◽  
Vol 210 ◽  
pp. 281-302 ◽  
Author(s):  
D. B. Ingham ◽  
T. Tang ◽  
B. R. Morton
Keyword(s):  
Finite Difference ◽  
Stokes Equations ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Corner Singularities ◽  
Flat Plates ◽  
Navier Stokes Equations ◽  
Flow Through ◽  
Good Agreement

A numerical and experimental study is described for the two-dimensional steady flow through a uniform cascade of normal flat plates. The Navier–Stokes equations are written in terms of the stream function and vorticity and are solved using a second-order-accurate finite-difference scheme which is based on a modified procedure to preserve accuracy and iterative convergence at higher Reynolds numbers. The upstream and downstream boundary conditions are discussed and an asymptotic solution is employed both upstream and downstream. A frequently used method for dealing with corner singularities is shown to be inaccurate and a method for overcoming this problem is described. Numerical solutions have been obtained for blockage ratio of 50 % and Reynolds numbers in the range 0 [les ]R[les ] 500 and results for both the lengths of attached eddies and the drag coefficients are presented. The calculations indicate that the eddy length increases linearly withR, at least up toR= 500, and that the multiplicative constant is in very good agreement with the theoretical prediction of Smith (1985a), who considered a related problem. In the case ofR= 0 the Navier–Stokes equations are solved using the finite-difference scheme and a modification of the boundary-element method which treats the corner singularities. The solutions obtained by the two methods are compared and the results are shown to be in good agreement. An experimental investigation has been performed at small and moderate values of the Reynolds numbers and there is excellent agreement with the numerical results both for flow streamlines and eddy lengths.

Sign in / Sign up

Export Citation Format

Share Document