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Wyświetlanie 1-5 z 5
Tytuł:
The analysis of separation and methods of three-dimensional flow structure detection in the boundary layer shock wave interaction
Autorzy:
Czerwińska, J.
Powiązania:
https://bibliotekanauki.pl/articles/1954539.pdf
Data publikacji:
1999
Wydawca:
Politechnika Gdańska
Tematy:
shock wave boundary layer interaction
flow separation
3D flow structures
numerical simulations
Opis:
The normal shock wave turbulent boundary layer interaction still draws a great deal of attention as a flow phenomenon. This is due to its profound importance to numerous applications. The understanding of phenomena is crucial for future aims connected with the interaction control. Experimental investigations of the interaction have been carried out since the 1940s. They were aimed however at the determination of such general flow features as: pressure distribution, shock wave configuration or oil visualization of separation structures. In order to better understand the phenomenon, measurements of the entire field are required. At present, such measurements do not exist. A great help is expected from numerical simulations in this respect. There is enough experimental data to check the general features of the flow obtained from calculations. This thesis presents numerical simulations of flow that is assumed: steady, three-dimensional, compressible, viscous and turbulent. Its general aim is to present to what extend the modern numerical methods are able to predict the flow in shock wave turbulent boundary layer interaction including shock induced separation structures. These structures are very sensitive to channel geometry and may be useful in the understanding of separation's development. In order to illustrate the abilities of numerical simulations, one aim of the presented thesis is to investigate the effect of the span-wise depth of the nominally two-dimensional test section. The presented results cast some light on the common problems experienced by typical comparisons of two-dimensional simulations to wind tunnel tests having a three-dimensional nature. The first Chapter presents the basic theory of elementary structures. Considerations of elementary structures of the flow along with their dependencies are necessary for a better understanding of the separation flow structures induced by the boundary layer shock wave interaction. The classification of elementary structures will be presented. In addition, the possible occurrence of bifurcation will also be studied. The second Chapter will be devoted to studying specific cases of transonic turbulent flow. The analysis of numerical results will be bounded to the shock wave structure. Studies shall include: the influence of the numerical scheme, three-dimensional effects connected with the changing width of the channel, a comparison to experiment and the influence of the symmetric boundary condition on the flow prediction in the channel. Finally, the boundary layer influence on the 1-foot structure will also be presented. Chapter three will present the separation structures. Here too a comparison to experiments will be done. Changes in separation structures connected with the width of the channel will be studied. The influence of the symmetry boundary condition will be shown. Finally, the specification of the basic flow structures will be done.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1999, 3, 1; 53-140
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulation of 3D flow in axial turbomachines
Autorzy:
Yershov, S.
Rusanov, A. V.
Gardzielewicz, A.
Lampart, P.
Świrdyczuk, J.
Powiązania:
https://bibliotekanauki.pl/articles/1953978.pdf
Data publikacji:
1998
Wydawca:
Politechnika Gdańska
Tematy:
numerical simulation
axial turbomachines
3D flow
3D viscous compressible flow
Navier-Stokes equation
ENO reconstruction
computational efficiency
computational fluid dynamics CFD
Godunov-type upwind differencing
Opis:
The paper is intended to describe a method for the calculation of 3D viscous compressible (subsonic or supersonic) flow in axial turbomachines described in the form of thin-layer Reynolds-averaged Navier-Stokes equations. The method draws on Godunov-type upwind differencing and ENO reconstruction suggested by Harten (1987), so as to assure monotonicity preservation and high accuracy of computational results. The computational efficiency is achieved thanks to the implementation of a simplified H-type multi-grid approach and delta -form implicit step. Turbulent effects are simulated with the help of a modified algebraic model of Baldwin-Lomax (1978). This method was at the foundation of a computer code-a complex software package to calculate 3D flow in multi-stage turbomachines that allows us to obtain local characteristics, like temperature, pressure, density or velocity distributions, as well as global characteristics, such as flow rates, stage reaction, flow efficiency for the considered turbine/compressor stage. The paper also gives selected results of computation of a number of turbomachinery cascades, showing that these results agree reasonably well with the available experimental data.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1998, 2, 2; 319-347
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulation of 3D flow in VKI-Genoa turbine cascade including laminar-turbulent transition
Autorzy:
Yerschov, S.
Derevyanko, A.
Yakovlev, V.
Gryzun, M.
Powiązania:
https://bibliotekanauki.pl/articles/1938601.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska
Tematy:
numerical simulation
3D flow
turbine cascade
laminar-turbulent transition
turbulence kinetic energy
secondary flows
losses
Opis:
This study presents a numerical simulation of a 3D viscous flow in the VKI-Genoa cascade taking into account the laminar-turbulent transition. The numerical simulation is performed using the Reynolds-averaged Navier-Stokes equations and the two-equation k-ω SST turbulence model. The algebraic Production Term Modification model is used for modeling the laminar-turbulent transition. Computations of both fully turbulent and transitional flows are carried out. The Mach number contours, the turbulence kinetic energy, the entropy function as well as the limiting streamlines are presented. Our numerical results demonstrate the influence of the laminar-turbulent transition on the secondary flow pattern. The comparison between the present computational results and the existing experimental and numerical data shows that the proposed approach reflects sufficiently the physics of the laminar-turbulent transition in turbine cascades.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2016, 20, 1; 43-61
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulation and modification of 3D flow phenomena in an axial flow fan
Autorzy:
Elhadi, E. E.
Keqi, W.
Powiązania:
https://bibliotekanauki.pl/articles/1954658.pdf
Data publikacji:
2003
Wydawca:
Politechnika Gdańska
Tematy:
axial flow fan
vortex
stagger angle
numerical simulation
3D
Opis:
This work aims to study and analyze the behavior of flow in an axial flow fan using numerical simulation based on solving Reynolds-averaged Navier-Stokes equations coupled with a modified Spalart-Allaras turbulence model. In the present work, different flow phenomena occuring in an axial flow fan were presented and interpreted at different design conditions and at different regions, with special concern to the rotor exit and stator regions. Large vortices and reverse flow at the stator suction side were observed under high loading conditions. These are mainly due to radial and centrifugal effects in the fluid due to a decreasing flow rate. To avoid this type of flow, the stator flow pattern has been modified using a new stator blade. This blade was designed by changing the stator stagger angle by 10o in the radial direction. This study indicates that the flow in the modified stator region behaves well and gives better performance than that obtained when using a baseline stator, especially under high loading conditions. This study also indicates that the stator stagger angle has a significant effect on modifying the fan performance.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2003, 7, 2; 199-213
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multiblock parallel computation of an incompressible 3D flow in turbomachines
Autorzy:
Papierski, A.
Rabiega, M.
Powiązania:
https://bibliotekanauki.pl/articles/1954540.pdf
Data publikacji:
1999
Wydawca:
Politechnika Gdańska
Tematy:
numerical simulations
turbomachinery
incompressible flow
3D Navier-Stockes solver
Navier-Stokes solver
parallel computing
Opis:
A finite volume numerical method for the prediction of a fluid flow in complex geometries such as turbomachinery channels has been parallelized using a domain decomposition approach. A mathematical formulation of a 3-D incompressible steady flow has been presented on the basis of the N-S equations in a grid-oriented co-ordinate system with contravariant velocity components. A parallelized pressure-based implicit algorithm with discretization on a staggered grid has been developed. A message exchange system with a boundary exchange, developed by the authors, has been described. Exemplary calculations have been carried out for a laminar flow through a curved duct and for an inviscid flow through a stage of the centrifugal pump. A good agreement has been obtained in both the cases. Despite considerable simplification that has been introduced in the flow through the pump stage, the computations have shown nearly the same pressure rise in the stage as the measurements. Further directions of numerical investigations of a flow through turbomachines, including in particular those devoted to pressure losses related to the rotor-stator interaction, have been mentioned.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1999, 3, 1; 39-52
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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