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.

Feasibility Study on Application of a Self-Formed Flow Field Downstream of Elbows to Divertor Cooling

2013 ◽  
Author(s):  
Shoichi Kodate ◽  
Tatsuya Kubo ◽  
Shinji Ebara ◽  
Hidetoshi Hashizume
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Reynolds Stress ◽  
Swirling Flow ◽  
Pipe Wall ◽  
Three Dimensional ◽  
High Heat ◽  
Turbulent Pipe Flow ◽  
High Heat Transfer ◽  
Piv Measurement

In this study, the characteristic of the swirling flow was analyzed in detail in terms of flow field by means of a visualization experiment using matched refractive index PIV measurement to evaluate the applicability of the swirling flow generated downstream of a three-dimensionally connected dual elbow to the divertor cooling. The dual elbow used in the experiment comprises two 90-degree elbows with the same curvature connected directly in three-dimensional configuration. From the experiment, it was found that strong swirling velocity component appears locally near the pipe wall downstream of the second elbow. Moreover, although the strength of the swirling flow changed gradually as it flowed downstream, it attenuated little even 8D downstream of the dual elbow, where D was the diameter of the piping. Therefore, this swirling flow is expected to survive for a considerable distance downstream of the elbow, and the applicability of this flow field to divertor cooling can be promising. Furthermore turbulence quantities such as Reynolds stress were analyzed in terms of heat transfer performance. Since there were some regions where larger Reynolds stress than a developed turbulent pipe flow was observed near the pipe wall, high heat transfer is expected there.

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.

Computational and experimental investigations in a cyclone dust separator

1997 ◽  
Vol 211 (4) ◽  
pp. 247-257 ◽  
Author(s):  
S M Fraser ◽  
A M Abdel-Razek ◽  
M Z Abdullah
Keyword(s):  
Flow Field ◽  
Richardson Number ◽  
Swirling Flow ◽  
Laser Doppler Anemometry ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Cyclone Chamber ◽  
Dust Separator

Three-dimensional turbulent flow in a model cyclone has been simulated using PHOENICS code and experimental studies carried out using a laser Doppler anemometry (LDA) system. The experimental results were used to validate the computed velocity distributions based on the standard and a modified k-∊ model. The standard k-∊ model was found to be unsatisfactory for the prediction of the flow field inside the cyclone chamber. By considering the strong swirling flow and the streamlined curvature, a k-∊ model, modified to take account of the Richardson number, provided better velocity distributions and better agreement with the experimental results.

Aerodynamics of Linearly Arranged Rad-Rad Swirlers, Effect of Number of Swirlers and Alignment

2013 ◽  
Author(s):  
Yi-Huan Kao ◽  
Samir B. Tambe ◽  
San-Mou Jeng
Keyword(s):  
Flow Field ◽  
Swirling Flow ◽  
Near Field ◽  
Aerodynamic Characteristics ◽  
Field Region ◽  
Clockwise Rotation ◽  
Swirling Jets ◽  
Entire Flow ◽  
High Turbulence ◽  
Series Of Experiments

A series of experiments have been conducted to study the aerodynamic characteristics of a confined swirling flow generated by multiple rad-rad swirlers arranged linearly. The rad-rad swirlers used in this study are identical, and consist of an inner, primary swirler generating counter-clockwise rotation and an outer, secondary swirler generating clockwise rotation. A two-component Laser Doppler Velocimetry (LDV) system was employed to measure the velocity in the flow field. Initial measurements were conducted on unconfined and confined flow generated by a single swirler to serve as the baseline reference for the multi-swirler arrangements. Tests were conducted for 3 and 5 swirlers arranged in a line, with a spacing of 2D between the swirler centers, where D is the swirler exit diameter. An additional 5 swirler configuration was tested, where the exit plane of the center swirler was shifted 3.2 mm (1/8 inch) in the streamwise direction. The flow field generated by the multi-swirler arrangement is very complex, due to the interaction between the swirling jets of adjacent swirlers. The number of swirlers is seen to have a clear impact on the entire flow structure, as well as each recirculation zone. For the 3 swirler arrangement, a weak CTRZ is observed for the center swirler, whereas strong CTRZs are observed for the two outer swirlers. For the 5 swirler arrangement, the CTRZ pattern for the 3 inner swirlers is the same strong-weak-strong as seen for the 3 swirler arrangements, with weak CTRZs observed for the two outer swirlers. Higher interaction between swirlers is observed for the 5 swirler arrangement, as compared to the case with 3 swirlers. Since the swirlers are identical, the region between swirlers features merging of two opposing swirling jets, producing high turbulence intensity in the near field region. For the case with the offset center swirler, the swirling jet from this swirler did not merge with its neighbors in the near field region. This resulted in strong CTRZ for the center swirler, accompanied by weaker CTRZs at its immediate neighbors, which is reverse of the CTRZ strength pattern observed for the initial 5 swirler arrangement.

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.

Numerical Prediction of Wakes in Cascades and Compressor Rotors Including the Effects of Mixing: Part I — Cascade Wakes Including the Effects of Incidence and Freestream Turbulence

1991 ◽  
Author(s):  
N. Suryavamshi ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Freestream Turbulence ◽  
Compressor Cascade ◽  
Pressure Loss Coefficient ◽  
Viscous Losses ◽  
Rate Of Decay ◽  
Entire Flow ◽  
High Reynolds

The results of a numerical investigation to predict the flow in the wake regions of compressor cascades, and wakes and mixing in rotors are presented in this paper. Part I deals with flow in compressor cascades including the effects of change in loading (incidence) and the inlet freestream turbulence intensity. Part II of the paper deals with the predictions of the rotor flow field, including wakes and spanwise mixing. The wake behaviour has been studied numerically using a three-dimensional incompressible Navier-Stokes solver with a high Reynolds number form of the k–ε turbulence model. The equations are solved using a time dependent implicit technique. The agreement between the measured data and predictions is good; including the wake profile, decay, and losses. The ability of the pseudo-compressibility scheme to predict the entire flow field including the wake profile and its decay characteristics, effect of loading and the viscous losses of a compressor cascade is demonstrated. The numerical analysis shows a slight increase in the total pressure loss coefficient through the cascade with increasing turbulence levels. The results also show a slight increase in the rate of decay of the wake at higher turbulence levels but the change in the spreading of the wake was found to be very small with increased turbulence levels.

scholarly journals Numerical Prediction of Wakes in Cascades and Compressor Rotors Including the Effects of Mixing: Part II — Rotor Passage Flow and Wakes Including the Effects of Spanwise Mixing

1991 ◽  
Author(s):  
N. Suryavamshi ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Axial Flow ◽  
Radial Component ◽  
Navier Stokes ◽  
Mean Velocity ◽  
Compressor Rotor ◽  
Entire Flow ◽  
High Reynolds ◽  
Flow Compressor

The results of a numerical investigation to predict the flow field including wakes and mixing in axial flow compressor rotors has been presented in this paper. The wake behaviour in a moderately loaded compressor rotor has been studied numerically using a three-dimensional incompressible Navier-Stokes solver with a high Reynolds number form of the k–ε turbulence model. The equations are solved using a time dependent implicit technique. The agreement between the measured data and the predictions are good; including the blade boundary layer profiles, wake mean velocity profiles and decay. The ability of the pseudo-compressibility scheme to predict the entire flow field including the near and far wake profiles and its decay characteristics, effect of loading and the viscous losses of a three-dimensional rotor flow field has been demonstrated. An analysis of the passage averaged velocities and the pressure coefficients shows that the mixing in the downstream regions away from the hub and annulus walls is dominated by wake diffusion. In regions away from the walls, the radial mixing is predominantly caused by the transport of mass, momentum and energy by the radial component of velocity in the wake.

Primary/Leakage Flow Interaction in a Pump Stage

1999 ◽  
Vol 121 (1) ◽  
pp. 133-138 ◽  
Author(s):  
E. A. Baskharone ◽  
N. J. Wyman
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Leakage Flow ◽  
Computational Domain ◽  
Primary Flow ◽  
Element Analysis ◽  
Impeller Blade ◽  
The Finite Element Analysis ◽  
Pump Stage ◽  
Entire Flow

The finite-element analysis of the combined primary and leakage flow streams in a centrifugal pump is presented. To date, this computational model provides the most accurate “zeroth-order” flow field for rotordynamic calculations, short of analyzing the entire flow field on a fully three-dimensional basis. In formulating the problem, the shaft work is modeled via the angular momentum it imparts to the primary flow stream across the impeller blade region. In casting the boundary conditions, special attention is paid to the multi-connectivity of the newly-contoured computational domain in such a way to avoid over-specification of the problem. The analysis is applied to a typical pump stage with a face seal being part of the leakage passage. The numerical results are then compared to the outcome of the existing lower-order analysis where the impeller subdomain was totally extracted.

Sign in / Sign up

Export Citation Format

Share Document