A Full Quasi-Three-Dimensional Calculation of Flow in Turbomachines

1988 ◽  
Vol 110 (3) ◽  
pp. 401-404 ◽  
Author(s):  
M. Ribaut
Keyword(s):  
Boundary Condition ◽  
Transverse Velocity ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Boundary Values ◽  
Streamwise Vorticity ◽  
Three Dimensional Flow ◽  
Cascade Flow ◽  
Condition Problem ◽  
Compatibility Function

The problem of calculating a three-dimensional flow with three families of two-dimensional solutions is considered. From a throughflow solution and several blade-to-blade solutions the boundary values of a set of transverse solutions are obtained. The resulting overdetermined boundary condition problem is solved by means of a compatibility function defining the divergence of the transverse velocity field. The influence of the latter on the blade-to-blade solution is formulated in two different ways and compared with the experiment. The new method should considerably improve the prediction of three-dimensional cascade flow presenting a large amount of streamwise vorticity in the meridional direction.

The mixing layer: deterministic models of a turbulent flow. Part 2. The origin of the three-dimensional motion

1984 ◽  
Vol 139 ◽  
pp. 67-95 ◽  
Author(s):  
G. M. Corcos ◽  
S. J. Lin
Keyword(s):  
Mixing Layer ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Streamwise Vorticity ◽  
Deterministic Models ◽  
Three Dimensional Flow ◽  
Turbulent Mixing Layer ◽  
Flow Part ◽  
Difference Calculation ◽  
Mechanism Of Growth

Experimental evidence suggests that in the turbulent mixing layer the fundamental mechanism of growth is two-dimensional and little affected by the presence of vigorous three-dimensional motion. To quantify this apparent property and study the growth of streamwise vorticity, we write for the velocity field \[ {\boldmath V}(x, t) = {\boldmath U}(x, z, t) + {\boldmath u}(x, y, z, t), \] where U is two-dimensional and u is three-dimensional. In a first version of the problem U is independent of u, while in the second U is the spanwise average of V. In both cases the equation for u is linearized around U. The equations for U and u are solved simultaneously by a finite-difference calculation starting with a slightly disturbed parallel shear layer.The solutions provide a detailed description of the growth of the three-dimensional motion. They show that its characteristics are dictated by the distribution of spanwise vorticity which results from roll-up and pairing. Pairing inhibits its growth. The solutions also demonstrate that even when the three-dimensional flow attains large amplitudes it has a negligible effect on the interaction of spanwise vortices and thus on the growth of the layer.

Three-dimensional flow in cavities

1963 ◽  
Vol 16 (4) ◽  
pp. 620-632 ◽  
Author(s):  
D. J. Maull ◽  
L. F. East
Keyword(s):  
Static Pressure ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Three Dimensional Flow ◽  
Large Span ◽  
Dimensional Flow ◽  
Pressure Distributions ◽  
Oil Flow ◽  
Two Dimensional Flow

The flow inside rectangular and other cavities in a wall has been investigated at low subsonic velocities using oil flow and surface static-pressure distributions. Evidence has been found of regular three-dimensional flows in cavities with large span-to-chord ratios which would normally be considered to have two-dimensional flow near their centre-lines. The dependence of the steadiness of the flow upon the cavity's span as well as its chord and depth has also been observed.

Cellular flow in a partially filled rotating drum: regular and chaotic advection

2017 ◽  
Vol 825 ◽  
pp. 631-650 ◽  
Author(s):  
Francesco Romanò ◽  
Arash Hajisharifi ◽  
Hendrik C. Kuhlmann
Keyword(s):  
Three Dimensional ◽  
Reynolds Numbers ◽  
Chaotic Advection ◽  
Two Dimensional ◽  
Rotating Drum ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Heteroclinic Connection ◽  
Two Dimensional Flow ◽  
Chaotic Streamlines

The topology of the incompressible steady three-dimensional flow in a partially filled cylindrical rotating drum, infinitely extended along its axis, is investigated numerically for a ratio of pool depth to radius of 0.2. In the limit of vanishing Froude and capillary numbers, the liquid–gas interface remains flat and the two-dimensional flow becomes unstable to steady three-dimensional convection cells. The Lagrangian transport in the cellular flow is organised by periodic spiralling-in and spiralling-out saddle foci, and by saddle limit cycles. Chaotic advection is caused by a breakup of a degenerate heteroclinic connection between the two saddle foci when the flow becomes three-dimensional. On increasing the Reynolds number, chaotic streamlines invade the cells from the cell boundary and from the interior along the broken heteroclinic connection. This trend is made evident by computing the Kolmogorov–Arnold–Moser tori for five supercritical Reynolds numbers.

Reconstruction of three-dimensional flow fields from two-dimensional data

2020 ◽  
Vol 407 ◽  
pp. 109239
Author(s):  
José Miguel Pérez ◽  
Soledad Le Clainche ◽  
José Manuel Vega
Keyword(s):  
Three Dimensional ◽  
Flow Fields ◽  
Two Dimensional ◽  
Three Dimensional Flow ◽  
Dimensional Flow

Axial Transport Effects on Natural Convection Inside of an Open-Ended Annulus

1991 ◽  
Vol 113 (3) ◽  
pp. 627-634 ◽  
Author(s):  
K. Vafai ◽  
J. Ettefagh
Keyword(s):  
Temperature Distribution ◽  
Flow Field ◽  
Three Dimensional ◽  
Transient Behavior ◽  
Temperature Fields ◽  
Two Dimensional ◽  
Three Dimensional Flow ◽  
Subsequent Effect ◽  
Transport Effects ◽  
Temperature And Velocity Fields

The present work centers around a numerical three-dimensional transient investigation of the effects of axial convection on flow and temperature fields inside an open-ended annulus. The transient behavior of the flow field through the formation of a three-dimensional flow field and its subsequent effect on the temperature distribution at different axial locations within the annulus were analyzed by both finite difference and finite element methods. The results show that the axial convection has a distinctly different influence on the temperature and velocity fields. It is found that in the midportion of the annulus a two-dimensional assumption with respect to the temperature distribution can lead to satisfactory results for Ra<10,000. However, such an assumption is improper with respect to the flow field. Furthermore, it is shown that generally the errors for a two-dimensional assumption in the midportion of the annulus are less at earlier times (t<50Δt) during the transient development of the flow and temperature fields.

Excess Streamwise Vorticity and Its Role in Secondary Flow

1987 ◽  
Vol 201 (6) ◽  
pp. 413-420 ◽  
Author(s):  
P W James
Keyword(s):  
Secondary Flow ◽  
Gas Turbines ◽  
Three Dimensional ◽  
Point Of View ◽  
Streamwise Vorticity ◽  
Three Dimensional Flow ◽  
Approximate Methods ◽  
Blade Row ◽  
Flow Through ◽  
Loss Term

The purpose of this paper is, firstly, to show how the concept of excess secondary vorticity arises naturally from attempts to recover three-dimensional flow details lost in passage-averaging the equations governing the flow through gas turbines. An equation for the growth of excess streamwise vorticity is then derived. This equation, which allows for streamwise entropy gradients through a prescribed loss term, could be integrated numerically through a blade-row to provide the excess vorticity at the exit to a blade-row. The second part of the paper concentrates on the approximate methods of Smith (1) and Came and Marsh (2) for estimating this quantity and demonstrates their relationship to each other and to the concept of excess streamwise vorticity. Finally the relevance of the results to the design of blading for gas turbines, from the point of view of secondary flow, is discussed.

Formation of a Counter-Rotating Vortex Pair in a Plume in a Cross-Flow

2010 ◽  
Author(s):  
Masahiko Shinohara
Keyword(s):  
Vortex Ring ◽  
Three Dimensional ◽  
Cross Flow ◽  
Vortex Pair ◽  
Boussinesq Approximation ◽  
Streamwise Vorticity ◽  
Three Dimensional Flow ◽  
Flow Feature ◽  
Heated Area ◽  
Counter Rotating Vortex Pair

Numerical simulations are performed to study the formation of a counter-rotating vortex pair (CVP), a dominant flow feature in plumes inclined in a cross-flow. The unsteady three-dimensional flow fields are calculated by a finite difference method using the Boussinesq approximation. A plume rises from an isothermally heated square surface facing upward in air. Calculations show that the CVP originates not from horizontal spanwise vorticity in the velocity boundary layer on the bottom wall around the heated area, but from horizontal streamwise vorticity just above each side of the heated area. When the cross-flow begins after a plume forms a vortex ring in the cap above the heated area in a still environment, the vortex ring does not form a CVP. However, as the cap and the stem of the plume move downwind, a rotation about the streamwise axis appears just above each side edge of the heated area and grows into the CVP. We discuss the effect of entrainment into the stem and cap on the formation of the streamwise rotation that causes the CVP.

Comparison of Two Base-Potentials for a Slender-Body Method

2012 ◽  
Author(s):  
Mahmoud Alidadi ◽  
Sander Calisal
Keyword(s):  
Three Dimensional ◽  
Slender Body ◽  
Surface Boundary ◽  
Two Dimensional ◽  
Three Dimensional Flow ◽  
Wave Elevation ◽  
Surface Boundary Conditions ◽  
Perturbation Potential ◽  
Order Of Magnitude ◽  
Body Method

The effects of two base-potentials on the accuracy of a slender-body method are studied in this paper. In the formulation for this method which is developed for the slender ships, the velocity potential is decomposed into a base-potential and a perturbation potential. Then using an order of magnitude analysis, the three-dimensional flow problem is simplified into a series of two-dimensional problems for the perturbation potential. These two-dimensional problems are solved with the linearized free surface boundary conditions, using a mixed Eulerian-Lagrangian method. Finally for the two base-potentials, the numerical wave elevation along a Wigleyull are compared with the experimental results.

Theoretical Aspects of Thrust Vector Control by Secondary Gas Injection in Rocket Nozzles

1968 ◽  
Vol 72 (686) ◽  
pp. 171-177 ◽  
Author(s):  
John H. Neilson ◽  
Alastair Gilchrist ◽  
Chee K. Lee
Keyword(s):  
Vector Control ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Three Dimensional Flow ◽  
Side Force ◽  
Thrust Vector Control ◽  
Dimensional Flow ◽  
Two Dimensional Flow ◽  
Thrust Vector ◽  
Secondary Injection

This work deals with theoretical aspects of thrust vector control in rocket nozzles by the injection of secondary gas into the supersonic region of the nozzle. The work is concerned mainly with two-dimensional flow, though some aspects of three-dimensional flow in axisymmetric nozzles are considered. The subject matter is divided into three parts. In Part I, the side force produced when a physical wedge is placed into the exit of a two-dimensional nozzle is considered. In Parts 2 and 3, the physical wedge is replaced by a wedge-shaped “dead water” region produced by the separation of the boundary layer upstream of a secondary injection port. The modifications which then have to be made to the theoretical relationships, given in Part 1, are enumerated. Theoretical relationships for side force, thrust augmentation and magnification parameter for two- and three-dimensional flow are given for secondary injection normal to the main nozzle axis. In addition, the advantages to be gained by secondary injection in an upstream direction are clearly illustrated. The theoretical results are compared with experimental work and a comparison is made with the theories of other workers.

Three-dimensional flow images by reconstruction from two-dimensional vector velocity maps

1995 ◽  
Vol 8 (6) ◽  
pp. 915-923 ◽  
Author(s):  
Laurence N. Bohs ◽  
Barry H. Friemel ◽  
Joseph Kisslo ◽  
Daniel T. Harfe ◽  
Kathryn R. Nightingale ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Two Dimensional ◽  
Dimensional Vector ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Vector Velocity
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