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.

Mixing and Combustion Improvement Using Jet Injection Into Swirling Flowfields

2002 ◽  
Author(s):  
David G. Lilley
Keyword(s):  
Research Program ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Computer Code ◽  
Theoretical Research ◽  
Mixing Efficiency ◽  
Jet Injection ◽  
Mean Velocity ◽  
Turbulence Data ◽  
Secondary Injection

The aerodynamics benefits of lateral jet injection into swirling crossflow have long been recognized and used by combustion engineers. Studies are reported here on experimental and theoretical research on lateral jet injection into typical combustor flowfields for low-speed turbulent swirling flow conditions in the absence of combustion. The main flow is air in a round cross-sectioned plexiglass tube. The degree of swirl can be varied by varying the angles of the blades of an annular swirler, located upstream of the test section. Lateral jet injection is normal to the main airflow, from round-sectioned nozzles. Either a single lateral jet or two diametrically opposed jets are used for this secondary injection of air into the main airflow. The principal aim is to investigate the trajectory, penetration and mixing efficiency of the lateral injection. Flow visualization with helium-filled soap bubbles and multi-spark ionized path techniques, five-hole pitot probe time-mean velocity measurements, and single-wire time-mean velocity and turbulence data (normal and shear stress) have been obtained in the experimental research program. A fully three-dimensional computer code with two-equation turbulence model has been developed and used in the theoretical research program.

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.

Mode interactions in an enclosed swirling flow: a double Hopf bifurcation between azimuthal wavenumbers 0 and 2

2002 ◽  
Vol 455 ◽  
pp. 263-281 ◽  
Author(s):  
F. MARQUES ◽  
J. M. LOPEZ ◽  
J. SHEN
Keyword(s):  
Hopf Bifurcation ◽  
Parameter Space ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Ekman Layer ◽  
Mode Interaction ◽  
Dimensional Structure ◽  
Navier Stokes ◽  
Double Hopf Bifurcation ◽  
Rotating Wave

A double Hopf bifurcation has been found of the flow in a cylinder driven by the rotation of an endwall. A detailed analysis of the multiple solutions in a large region of parameter space, computed with an efficient and accurate three-dimensional Navier-Stokes solver, is presented. At the double Hopf point, an axisymmetric limit cycle and a rotating wave bifurcate simultaneously. The corresponding mode interaction generates an unstable two-torus modulated rotating wave solution and gives a wedge-shaped region in parameter space where the two periodic solutions are both stable. By exploring in detail the three-dimensional structure of the flow, we have identified the two mechanisms that compete in the neighbourhood of the double Hopf point. Both are associated with the jet that is formed when the Ekman layer on the rotating endwall is turned by the stationary sidewall.

Jet Injection Into Swirling Crossflow for Improved Mixing and Combustion

2002 ◽  
Author(s):  
David G. Lilley
Keyword(s):  
Research Program ◽  
Swirling Flow ◽  
Three Dimensional ◽  
Computer Code ◽  
Theoretical Research ◽  
Mixing Efficiency ◽  
Jet Injection ◽  
Mean Velocity ◽  
Turbulence Data ◽  
Secondary Injection

The aerodynamics benefits of lateral jet injection into swirling crossflow have long been recognized and used by combustion engineers. Studies are reported here on experimental and theoretical research on lateral jet injection into typical combustor flowfields for low-speed turbulent swirling flow conditions in the absence of combustion. The main flow is air in a round cross-sectioned plexiglass tube. The degree of swirl can be varied by varying the angles of the blades of an annular swirler, located upstream of the test section. Lateral jet injection is normal to the main airflow, from round-sectioned nozzles. Either a single lateral jet or two diametrically opposed jets are used for this secondary injection of air into the main airflow. The principal aim is to investigate the trajectory, penetration and mixing efficiency of the lateral injection. Flow visualization with helium-filled soap bubbles and multi-spark ionized path techniques, five-hole pitot probe time-mean velocity measurements, and single-wire time-mean velocity and turbulence data (normal and shear stress) have been obtained in the experimental research program. A fully three-dimensional computer code with two-equation turbulence model has been developed and used in the theoretical research program. The present paper reviews the activity and highlights key results obtained during the study.

Flow Measurements in a Model Burner—Part 1

1991 ◽  
Vol 113 (4) ◽  
pp. 668-674 ◽  
Author(s):  
D. F. G. Dura˜o ◽  
M. V. Heitor ◽  
A. L. N. Moreira
Keyword(s):  
Velocity Ratio ◽  
Laser Doppler ◽  
Jet Flows ◽  
Mixing Efficiency ◽  
Mixing Rate ◽  
Flow Measurements ◽  
Seed Particles ◽  
Circular Jets ◽  
Unequal Number ◽  
Air Streams

Laser-Doppler measurements of mean and turbulent velocity characteristics are reported in the developing region of the isothermal flow of a model of an industrial oxy-fuel burner. The burner consists of a central axisymmetric jet surrounded by sixteen circular jets, simulating the injection of oxygen in pratical burners. Errors incurred in the laser-Doppler measurements are estimated and bias effects due to unequal number density of seed particles in the various jet flows are investigated. The experiments have been carried out to investigate the mixing efficiency of the burner assembly without swirl motion and to assess the accuracy of calculation procedures in industrial burners. The results show that the present flow develops faster than related coaxial free jets with the same velocity ratio between central and peripheral air streams due to the comparatively high mixing rate peculiar to the present configuration. The existence of zones characterized by large turbulence anisotropy indicates the need to take account of the normal stresses in any proposed mathematical model to simulate the present flow field.

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).

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.

Sign in / Sign up

Export Citation Format

Share Document