Vorticity Modeling of Blade Wakes behind Isolated Annular Blade-Rows: Induced Disturbances in Swirling Flows

1981 ◽  
Vol 103 (2) ◽  
pp. 279-287 ◽  
Author(s):  
C. S. Tan
Keyword(s):  
Swirling Flow ◽  
Three Dimensional ◽  
Stagnation Pressure ◽  
Swirling Flows ◽  
Axial Distance ◽  
Free Vortex ◽  
Blade Row ◽  
Type 3 ◽  
Theoretical Considerations ◽  
Type Potential

A general analysis is proposed for studying the fluid-mechanical behavior of blade wakes from an annular blade-row in highly swirling flow. The coupling between the centrifugal force and the vorticity, which is inherent to highly swirling flows, can significantly modify the wake behavior from that in a two-dimensional situation. In steady flow, theoretical considerations show that a blade wake consists primarily of two distinct types of vorticity: (1) trailing vorticity shed from the blade due to a spanwise variation in blade circulation; and (2) vorticity associated with defects in stagnation pressure (or rotary stagnation in relative coordinate system). Three types of disturbances can be identified in the resulting three-dimensional disturbance field: (1) the exponentially decaying type (potential, irrotational), (2) the purely convected type (rotational), and (3) the nonconvected type (both rotational and irrotational parts). Type (3) arises because of the interaction of centrifugal and Coriolis forces with (1) and (2). It is found that near the blade row the nonconvected disturbances grow linearly in magnitude with the axial distance. However, although those nonconvected disturbances associated with the trailing vorticity (also called Beltrami vorticity) persist for moderate distances downstream, they eventually decay inversely with the axial distance, irrespective of the types of swirl distribution. In contrast, those parts of nonconvected disturbances which are induced by the vorticity caused by (rotary) stagnation pressure defects persist indefinitely downstream for any type of swirl other than free-vortex. In the limit of free-vortex swirl, all disturbances decay at least inversely with the axial distance downstream.

scholarly journals Vorticity Modelling of Blade Wakes Behind Isolated Annular Blade-Rows: Induced Disturbances in Swirling Flows

1980 ◽  
Author(s):  
C. S. Tan
Keyword(s):  
Coordinate System ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Stagnation Pressure ◽  
Swirling Flows ◽  
Two Dimensional ◽  
Blade Row ◽  
Theoretical Considerations ◽  
Type Potential ◽  
Disturbance Field

A general analysis is proposed for studying the fluid-mechanical behavior of blade wakes from an annular blade-row in highly swirling flow. The coupling between the centrifugal force and the vorticity, which is inherent to highly swirling flows, can significantly modify the wake behavior from that in a two-dimensional situation. In steady flow, theoretical considerations show that a blade wake consists primarily of two distinct types of vorticity: a) trailing vorticity shed from the blade due to a span wise variation in blade circulation, and b) vorticity associated with defects in stagnation pressure (or rotary stagnation in relative coordinate system). Three types of disturbances can be identified in the resulting three-dimensional disturbance field: a) the exponentially decaying type (potential, irrotational), b) the purely convected type (rotational), and c) the non-convected type (both rotational and irrotational parts).

Flow Measurements in a Model Burner—Part 2

1993 ◽  
Vol 115 (2) ◽  
pp. 309-316
Author(s):  
D. F. G. Dura˜o ◽  
M. V. Heitor ◽  
A. L. N. Moreira
Keyword(s):  
Laser Doppler Velocimetry ◽  
Swirling Flow ◽  
Laser Sheet ◽  
Three Dimensional ◽  
Swirling Flows ◽  
Dimensional Structure ◽  
Mixing Efficiency ◽  
Flow Measurements ◽  
Circular Jets ◽  
Turbulence Production

The isothermal swirling flow in the vicinity of a model oxy-fuel industrial burner is analyzed with laser-Doppler velocimetry together with laser-sheet visualization. The burner consists of a central axisymmetric swirling jet surrounded by sixteen circular jets, simulating the injection of oxygen in practical burners. The results extend those obtained for non-swirling flows, and presented in Part 1 of this paper, to the analysis of the dependence of the mixing efficiency of the burner assembly upon the swirl motion of the central jet and have the necessary detail to allow to assess the accuracy of calculation procedures of the flow in industrial burners. It is shown that swirl attenuates the three-dimensional structure typical of multijet flows in such a way that turbulence production and transport in the near burner zone are dominated by swirl-induced processes.

On the Use of the Squire-Long Equation to Estimate Radial Velocities in Swirling Flows

2006 ◽  
Vol 129 (2) ◽  
pp. 209-217 ◽  
Author(s):  
Michel J. Cervantes ◽  
L. Håkan Gustavsson
Keyword(s):  
Boundary Conditions ◽  
Radial Velocity ◽  
Swirling Flow ◽  
Draft Tube ◽  
Three Dimensional ◽  
Swirling Flows ◽  
Laser Doppler Velocimeter ◽  
Test Case ◽  
Swirl Number ◽  
Experimental Values

A method to estimate the radial velocity in swirling flows from experimental values of the axial and tangential velocities is presented. The study is motivated by the experimental difficulties to obtain this component in a draft tube model as evidenced in the Turbine-99 IAHR∕ERCOFTAC Workshop. The method uses a two-dimensional nonviscous description of the flow. Such a flow is described by the Squire-Long equation for the stream function, which depends on the boundary conditions. Experimental values of the axial velocities at the inlet and outlet of the domain are used to obtain the boundary conditions on the bounded domain. The method consists of obtaining the equation related to the domain with an iterative process. The radial velocity profile is then obtained. The method may be applied to flows with a swirl number up to about Sw=0.25. The critical value of the swirl number depends on the velocity profiles and the geometry of the domain. The applicability of the methodology is first performed on a swirling flow in a diffuser with a half angle of 3deg at various swirl numbers, where three-dimensional (3D) laser Doppler velocimeter (LDV) velocity measurements are available. The method is then applied to the Turbine-99 test case, which consists in a model draft tube flow where the radial inlet velocity was undetermined. The swirl number is equal to Sw=0.21. The stability and the convergence of the approach is investigated in this case. The results of the pressure recovery are then compared to the experiments for validation.

The entrainment envelope of dye-core vortices at submerged hydraulic intakes

2002 ◽  
Vol 29 (3) ◽  
pp. 400-408 ◽  
Author(s):  
E C Carriveau ◽  
R E Baddour ◽  
G A Kopp
Keyword(s):  
Water Surface ◽  
Laboratory Experiments ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Swirling Flows ◽  
Surface Phenomenon ◽  
Acoustic Doppler Velocimeter ◽  
Velocity Measurements ◽  
Frazil Ice ◽  
Hydraulic Intake

Each winter in Canada, operational difficulties are encountered at various water works resulting from intake blockages caused by frazil ice entrainment. In a lake setting, frazil is a surface phenomenon, the strong downward current produced by a swirling flow, with an intake vortex present, provides a mechanism by which frazil is transported from the water surface to the submerged intake below. Laboratory experiments were conducted to study the entrainment envelope associated with swirling and non-swirling flows into submerged water intakes. Three-dimensional velocity measurements were made with an acoustic Doppler velocimeter. The results clearly show that the entrainment envelope for swirling flow is several times larger than that for non-swirling flow. This paper details, for a given set of conditions, the differences in the non-swirling and swirling flow entrainment envelopes and emphasizes the potential difficulties with frazil ice that vortices can cause at intakes.Key words: vortex, dye-core vortex, submerged hydraulic intake, entrainment envelope, three-dimensional velocity measurements, acoustic Doppler velocimeter.

Numerical Investigation on Single-Restricted Swirling Flows in an Innovative Combustor

2018 ◽  
Author(s):  
Bin Hu ◽  
JunHua Zhang ◽  
AiMing Deng ◽  
Wei Zhao ◽  
QingJun Zhao
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Swirling Flow ◽  
Flow Direction ◽  
Reacting Flows ◽  
Swirling Flows ◽  
Pollutant Emissions ◽  
Axial Distance ◽  
Critical Mode ◽  
Single Vortex

The size and fuel consumption as well as the pollutant emissions of gas turbine combustors have to be significantly reduced in the future, which brings new challenges to the design of combustors. An innovative gas turbine combustor, named Short Helical Combustor (SHC) has been proposed by B. Ariatabar et al. The major feature of SHC is that the swirling flow originated from a single swirler is only restricted by one side in circumferential direction which is greatly different than traditional combustors. The present work of this paper is to investigate the features of the single-restricted swirling flows in a model SHC by adjusting the axial distance (L) between adjacent swirlers. The relevant results show that, 1. In non-reacting flows, with the increase of L, the flow field downstream the swirler successively presents four modes: traditional mode, single-vortex mode, critical mode and double-vortices mode. When L = 0, a pair of counterrotating vortices exists in combustor. When 0.27H < L < 0.67H, only one vortex exists downstream the swirler. When 0.68H < L < 1.73H, another counter-rotating vortex gradually appears close to the unrestricted side. 2. With the increasing of L, the aerodynamic boundary is gradually formed on the unrestricted side in the reacting and non-reacting flows, which is the primary reason for the formation of vortex B. 3. The specific value of L of critical mode in reacting flows is larger than that in non-reacting flows because the gas expansion caused by combustion goes against the formation of aerodynamic boundary. 4. The velocity direction of the flows downstream the recirculation varies at different vortex modes in reacting and non-reacting flows. In non-reacting flows, the flow direction changes almost 180° as L is increased from 0.27H–1.73H. In reacting flows, the flow direction gradually varies from circumference to axis as L is increased from 0.27H–1.73H. The present work details the feature of the flow field in SHC, which is great meaningful to the design and improvement of the combustor.

Asymmetric Swirling Flows in Turbomachine Annuli

1978 ◽  
Vol 100 (4) ◽  
pp. 618-629 ◽  
Author(s):  
E. M. Greitzer ◽  
T. Strand
Keyword(s):  
Experimental Investigation ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Swirling Flows ◽  
Experimental Measurements ◽  
Strongly Coupled ◽  
Flow Disturbances ◽  
Different Types ◽  
Theoretical Predictions ◽  
Good Agreement

An analytical and experimental investigation of asymmetric annular swirling flows is presented. It is shown that, in contrast to the situation in nonswirling flow, the different types of flow disturbances (pressure and vorticity) are not separable in a swirling flow but are strongly coupled. The flows that occur due to this coupling are inherently three-dimensional and exhibit new features not seen in the nonswirling case. The theoretical predictions are in good agreement with experimental measurements carried out in an annular swirl rig.

Analytical Investigations of Incompressible Turbulent Swirling Flow in Stationary Ducts

1969 ◽  
Vol 36 (2) ◽  
pp. 151-158 ◽  
Author(s):  
A. Rochino ◽  
Z. Lavan
Keyword(s):  
Flow Field ◽  
Transport Theory ◽  
Swirling Flow ◽  
Pipe Wall ◽  
Three Dimensional ◽  
Eddy Diffusivity ◽  
Small Region ◽  
Swirling Flows ◽  
Entire Flow ◽  
Vorticity Transport

Turbulent swirling flows in stationary cylindrical ducts were investigated analytically using Taylor’s modified vorticity transport theory and von Karman’s similarity hypothesis extended to consider a three-dimensional fluctuating velocity field. The resulting similarity conditions were used to formulate the expression for eddy diffusivity in the entire flow field except in a small region near the pipe wall where a mixing-length expression analogous to that assumed by Prandtl for parallel flow in channels was used. The swirl equation was solved numerically using a constant that was obtained indirectly from an experiment by Taylor, and the analytical results were compared with two different sets of experimental measurements. In both cases, the agreement between experiment and analysis was satisfactory. Some discrepancies appeared when the flow field was predominantly irrotational or in solid-body rotation: This might have been expected since, for these situations, some of the similarity conditions were indeterminate or infinite.

THREE-DIMENSIONAL LAMINAR SWIRLING FLOW IN A PIPE

2019 ◽  
Author(s):  
Rodrigo Vidal Cabral ◽  
Andre Damiani Rocha
Keyword(s):  
Swirling Flow ◽  
Three Dimensional

scholarly journals Through-Flow Analysis for Axial-Stage Design Including Streamline-Slope Effects

1993 ◽  
Author(s):  
Theodosios Korakianitis ◽  
Dequan Zou
Keyword(s):  
Mass Flow ◽  
Three Dimensional ◽  
Momentum Equation ◽  
Total Enthalpy ◽  
Streamline Curvature ◽  
Flow Balance ◽  
Through Flow ◽  
Blade Row ◽  
Iteration Loop ◽  
Predictor Corrector

This paper presents a new method to design (or analyze) subsonic or supersonic axial compressor and turbine stages and their three-dimensional velocity diagrams from hub to tip by solving the three-dimensional radial-momentum equation. Some previous methods (matrix through-flow based on the streamfunction approach) can not handle locally supersonic flows, and they are computationally intensive when they require the inversion of large matrices. Other previous methods (streamline curvature) require two nested iteration loops to provide a converged solution: an outside iteration loop for the mass-flow balance; and an inside iteration loop to solve the radial momentum equation at each flow station. The present method is of the streamline-curvature category. It still requires the iteration loop for the mass-flow balance, but the radial momentum equation at each flow station is solved using a one-pass numerical predictor-corrector technique, thus reducing the computational effort substantially. The method takes into account the axial slope of the streamlines. Main design characteristics such as the mass-flow rate, total properties at component inlet, hub-to-tip ratio at component inlet, total enthalpy change for each stage, and the expected efficiency of each streamline at each stage are inputs to the method. Other inputs are the radial position and axial velocity component at one surface of revolution through the axial stages. These can be provided for either the hub, or the mean, or the tip location of the blading. In addition the user specifies the azimuthal deflection of the flow from the axial direction at each radius (or as a function of radius) at each blade row inlet and outlet. By construction the method eliminates radial variations of total enthalpy (work) and entropy at each blade row inlet and outlet. In an alternative formulation enthalpy variations across radial positions at each axial station are included in the analysis. The remaining three-dimensional velocity diagrams from hub to tip, and the radial location of the remaining streamlines, are obtained by solving the momentum equation using a predictor-corrector method. Examples for one turbine and one compressor design are included.

Calculation of the Quasi Three-Dimensional Flow in a Turbomachine Blade Row

1977 ◽  
Vol 99 (1) ◽  
pp. 53-62 ◽  
Author(s):  
Jean-Pierre Veuillot
Keyword(s):  
Finite Difference ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Through Flow ◽  
Blade Row ◽  
Time Marching ◽  
Space Discretization ◽  
Finite Volume Approach ◽  
Marching Method ◽  
Finite Difference Techniques

The equations of the through flow are obtained by an asymptotic theory valid when the blade pitch is small. An iterative method determines the meridian stream function, the circulation, and the density. The various equations are discretized in an orthogonal mesh and solved by classical finite difference techniques. The calculation of the steady transonic blade-to-blade flow is achieved by a time marching method using the MacCormack scheme. The space discretization is obtained either by a finite difference approach or by a finite volume approach. Numerical applications are presented.

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