Turbulent Viscosities for Swirling Flow in a Stationary Annulus

1973 ◽  
Vol 95 (4) ◽  
pp. 557-566 ◽  
Author(s):  
C. J. Scott ◽  
D. R. Rask
Keyword(s):  
Reynolds Number ◽  
Swirling Flow ◽  
Tangential Velocity ◽  
Outer Wall ◽  
Velocity Fields ◽  
Diameter Ratio ◽  
Working Fluid ◽  
Reduction Techniques ◽  
Annular Geometry ◽  
Tangential Momentum

Developing axial and decaying tangential velocity fields are surveyed in a stationary annulus with a nearly free vortex initial swirl distribution. Isothermal air was used as the working fluid in an annulus with a single diameter ratio (di/d0 = 0.4) and at a single axial bulk Reynolds number of 1.3 × 105. The annular geometry was selected because the inner and outer wall curvatures yield opposite effects on the swirl turbulence. The discussion is centered on a critical exposure of the data reduction techniques (momentum integrals) for obtaining the radial variations of the axial and tangential momentum diffusivities.

Stereo-PIV Measurements of Turbulent Swirling Flow Inside a Pipe

2020 ◽  
Author(s):  
Ayesha Almheiri ◽  
Lyes Khezzar ◽  
Mohamed Alshehhi ◽  
Saqib Salam ◽  
Afshin Goharzadeh
Keyword(s):  
Swirling Flow ◽  
Reverse Flow ◽  
Tangential Velocity ◽  
Circular Disk ◽  
Pipe Diameter ◽  
Working Fluid ◽  
Complex Flow ◽  
Mean Velocity ◽  
Radial Profiles ◽  
The Mean

Abstract Stereo-PIV is used to map turbulent strongly swirling flow inside a pipe connected to a closed recirculating system with a transparent test section of 0.6 m in length and a pipe diameter of 0.041 m. The Perspex pipe was immersed inside a water trough to reduce the effects of refraction. The working fluid was water and the Reynolds number based on the bulk average velocity inside the pipe and pipe diameter was equal to 14,450. The turbulent flow proceeds in the downstream direction and interacts with a circular disk. The measurements include instantaneous velocity vector fields and radial profiles of the mean axial, radial and tangential components of the velocity in the regions between the swirler exit and circular disk and around this later. The results for mean axial velocity show a symmetric behavior with a minimum reverse flow velocity along the centerline. As the flow developed along the pipe’s length, the intensity of the reversed flow was reduced and the intensity of the swirl decays. The mean tangential velocity exhibits a Rankine-vortex distribution and reached its maximum around half of the pipe’s radius. As the flow approaches the disk, the flow reaches stagnation and a complex flow pattern of vortices is formed. The PIV results are contrasted with LDV measurements of mean axial and tangential velocity. Good agreement is shown over the mean velocity profiles.

Streamwise Development of Co-Rotating, Paired Vortices Created by Tangential Injection

2003 ◽  
Author(s):  
Mary V. Holloway ◽  
Heather L. McClusky ◽  
Donald E. Beasley
Keyword(s):  
Swirling Flow ◽  
Tangential Velocity ◽  
Reynolds Numbers ◽  
Velocity Fields ◽  
Flow Structures ◽  
Lateral Velocity ◽  
Swirl Generator ◽  
Swirl Chamber ◽  
Image Velocimetry ◽  
Downstream Development

The present experimental study investigates the interaction and downstream development of two localized swirling flow structures created using a tangential injection method. A swirl generator is placed at the inlet of a 52.1 mm diameter pipe. The swirl generator consists of two swirl chambers with inner diameters of 23.8 mm. Each swirl chamber has a design swirl number of 7.14. Water is injected into each swirl chamber by two tangential injection ports. The injection ports are tangent to the swirl chamber and perpendicular to the axis of the pipe. The two co-rotating vortices created in the swirl generator interact freely within the pipe downstream of the swirl generator. The objective of the present study is to document the interaction between the two vortices and the downstream development of the flow. Lateral velocity fields are obtained using particle image velocimetry (PIV). Time-averaged lateral velocity fields and tangential velocity profiles are presented for several axial locations downstream of the swirl generator. Reynolds numbers of 11,000 and 17,000 are investigated. Results document the streamwise development and interaction between the two co-rotating vortices created by tangential injection. As the two swirling structures develop in the streamwise direction, three different types of flow patterns are identified. The first consists of two distinct swirling flow structures. Further downstream of the swirl chamber, the two swirling structures merge and form a single swirling flow structure with an elliptic core. In the third flow pattern, the center core of the swirling flow has a circular shape.

Particle image velocimetry studies on the swirling flow structure in the vortex gripper

2012 ◽  
Vol 227 (9) ◽  
pp. 1927-1937 ◽  
Author(s):  
Qiong Wu ◽  
Qian Ye ◽  
GuoXiang Meng
Keyword(s):  
Reynolds Number ◽  
Particle Image Velocimetry ◽  
Turbulent Flow ◽  
Flow Structure ◽  
Particle Image ◽  
Swirling Flow ◽  
Tangential Velocity ◽  
Internal Flow ◽  
Dynamics Simulation ◽  
Image Velocimetry

In this article, particle image velocimetry was used to measure the two-dimensional flow field for vortex gripper. The vortex gripper was divided into two parts for respective research, including vortex cup and the gas film gap. In the part of vortex cup, the tangential velocity increases gradually, and the velocity decreases intensely in the vicinity of the vortex cup’s wall after it reaches maximum. In addition, the velocity decreases gradually with the increase of the gas film gap. In the part of gas film gap, the tangential velocity increases to maximum along the radial direction first; after the air flows into the gas film gap due to the viscous impedance, it decreases gradually. When the gas film gap’s thickness is smaller, the velocity almost decreases to zero at the external edge of the skirt. However, when the gas film gap increases to a certain thickness, the velocity does not decrease to zero, and the flow air still keeps a certain speed out of it. The velocity decreases gradually with the increase of the gas film gap. The radial velocity in the vortex cup and the gas film gap is of very small order of magnitude comparing with the average velocity and tangential velocity. The analysis of the Reynolds number shows that the flow in the vortex cup is the turbulent flow, and at the part of the gas film gap, the Reynolds number increases with the increase of the gas film gap, and the flow changes from the laminar flow to the turbulent flow. Through the particle image velocimetry experiment, the vortex gripper’s internal flow structure is studied. It is the theory support of the computational fluid dynamics simulation study for vortex gripper and the structure optimization in the future work.

Decaying Annular Swirl Flow With Inlet Solid Body Rotation

1976 ◽  
Vol 98 (1) ◽  
pp. 33-40 ◽  
Author(s):  
C. J. Scott ◽  
K. W. Bartelt
Keyword(s):  
Experimental Data ◽  
Angular Momentum ◽  
Swirling Flow ◽  
Tangential Velocity ◽  
Swirl Flow ◽  
Working Fluid ◽  
Pressure Probe ◽  
Axial Component ◽  
Profile Shape ◽  
Straight Flow

An experimental investigation of a low-speed turbulent swirling flow in a stationary, concentric, annular duct was made. The experiment involved isothermal air as the working fluid in an annulus with a diameter ratio di/d0 = 0.4, an average axial Reynolds number of 72,000, and an average axial velocity of 15 m/s. The swirl profile initially induced at the inlet was of the forced-vortex type. The rate of swirl, or the magnitude of the tangential velocity relative to the axial component, decayed axially from the inlet. Three different swirl rates were considered, one being straight flow. Extensive measurements were made of the velocity field with a cylindrical pressure probe at seven stations located 1.7 to 32.7 equivalent diameters from the entrance. The specific goals were experimental data on the axial decay of angular momentum and inferred values of the effective turbulent tangential viscosity. Results show a uniform axial decay of angular momentum and a profile shape independent of axial location. An empirical model using tangential eddy diffusivities that vary over the cross-section gave the best description of experimental data. The tangential profile shape and tangential viscosity distribution and magnitude did not depend on the initial rate of swirl.

scholarly journals Numerical study of perforated plate convective heat transfer

2014 ◽  
Vol 18 (3) ◽  
pp. 949-956 ◽  
Author(s):  
Mladen Tomic ◽  
Predrag Zivkovic ◽  
Mica Vukic ◽  
Gradimir Ilic ◽  
Mladen Stojiljkovic
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Reynolds Number ◽  
Numerical Study ◽  
Plate Thickness ◽  
Perforated Plate ◽  
Diameter Ratio ◽  
Working Fluid ◽  
The Difference ◽  
The Heat Transfer Coefficient

Numerical simulations were performed to determine the heat transfer coefficient of a perforated plate with square arranged cylindrical perforations. Three parameters were varied in the study: plate porosity, pitch Reynolds number and working fluid, while perforation diameter and plate thickness were constant. The Reynolds number was varied in the range from 50 to 7000, and porosity in the range from 0.1 to 0.3. As working fluids, helium, air or carbon-dioxide were set, respectively. The Nusselt number was correlated in the function of the Reynolds number, the Prandtl number, and the pitch-to-diameter ratio. The comparison with other correlations is given at the end of the paper. The difference was found to be acceptable.

scholarly journals Analytical Velocity Study in a Conical Diffuser with Screw Tape Inserts

2018 ◽  
Vol 153 ◽  
pp. 06003
Author(s):  
Ehan Sabah Shukri
Keyword(s):  
Reynolds Number ◽  
Numerical Analysis ◽  
Boundary Conditions ◽  
Velocity Distribution ◽  
Numerical Simulations ◽  
Swirling Flow ◽  
Working Fluid ◽  
Aspect Ratios ◽  
Conical Diffuser ◽  
Better Than

A study is made to enhance the rate of velocity distribution in a conical diffuser. In this work, a numerical analysis on screw tape inserts in a conical diffuser is presented. In the numerical simulations, the swirling flow was introduced by using rectangular screw tape placed inside the inner test wall of the conical diffuser. Screw tape with different aspect ratios (AS) 2.5, 3.5, 4.5, 6.5 and 7.5 was analysed. The simulations were carried out with constant inlet condition considering the flow turbulent and incompressible with inlet Reynolds number 3.2 × 105. The simulations were performed using air as a working fluid. The results obtained from the conical diffuser with screw tape inserts are compared with those without screw tape (plain conical diffuser). On the basis of the same inlet boundary conditions for the screw tape in the conical diffuser and the plain conical diffuser, it was found that the velocity distribution performance of screw tape inserts with different AS is better than plain conical diffuser. It is also observed that the screw tape with AS 3.5 offered the best velocity distribution rate.

scholarly journals Turbulent Swirling Flow in Short Cylindrical Chambers

1993 ◽  
Vol 115 (3) ◽  
pp. 444-451 ◽  
Author(s):  
A. Riahi ◽  
P. G. Hill
Keyword(s):  
Reynolds Number ◽  
Swirling Flow ◽  
Laser Doppler Anemometry ◽  
Reynolds Numbers ◽  
Diameter Ratio ◽  
Cylindrical Chamber ◽  
Transient Conditions ◽  
Chamber Length ◽  
Smooth Disk ◽  
Length To Diameter Ratio

Turbulent swirling flow in a short closed cylindrical chamber has been measured with laser Doppler anemometry. The swirl was generated by a rotating roughened disk and measured during steady and transient conditions with a smooth disk. The velocity and turbulence fields were found to be strongly dependent on swirl Reynolds numbers (in the range 0.3 × 106 < ΩR2/v < 0.6 × 106) and on chamber length-to-diameter ratio (in the range 0.1 ≤ L/D ≤ 0.5). With a roughened disk the flow was nearly independent of Reynolds number though still strongly dependent on chamber length-to-diameter ratio.

scholarly journals Sealing Flow Requirements for a Rotating Disk With External Swirling Flow

1994 ◽  
Author(s):  
Michael G. Izenson ◽  
Waiter L. Swift ◽  
Ronald H. Aungier
Keyword(s):  
Swirling Flow ◽  
Tangential Velocity ◽  
Rotating Disk ◽  
External Flow ◽  
Turbine Disk ◽  
Working Fluid ◽  
Published Data ◽  
Rotating Disks ◽  
Hot Gas ◽  
Process Gas

Experiments have been performed to investigate the sealing flow requirements for a shrouded, rotating disk with external swirling flow. In some gas turbine applications, it is desirable to provide sealing flow to prevent ingress of process gas into the cavity between the turbine disk and its stator. The tangential or swirl component in flow leaving the nozzles can significantly affect the amount of flow required to seal the turbine disk. The experimental flow model used water as a working fluid and was hydrodynamically scaled to match conditions typical of hot gas expander turbines used for energy recovery in the petrochemical industry. Flow in the seal gap was observed using a stream of dye injected on the stator face near the periphery. Differential pressures were measured on the stator face and related to the observed direction of flow on the stator face. The pressures and sealing flows were normalized by the disk and gap geometry and the applied flow conditions, then compared to published data for shrouded, rotating disks with no applied, external flow. For tests where the external tangential velocity was roughly equal to twice the rim speed of the disk, sealing flow requirements were found to be 1.5 to 2.0 times greater than for a disk without the applied, external flow.

An example of steady laminar flow at large Reynolds number

1960 ◽  
Vol 9 (4) ◽  
pp. 593-602 ◽  
Author(s):  
Iam Proudman
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Boundary Layers ◽  
Tangential Velocity ◽  
Fluid Flows ◽  
The Other ◽  
Large Reynolds Number ◽  
Rotational Flows ◽  
Flow Domain ◽  
Source Of Information

The purpose of this note is to describe a particular class of steady fluid flows, for which the techniques of classical hydrodynamics and boundary-layer theory determine uniquely the asymptotic flow for large Reynolds number for each of a continuously varied set of boundary conditions. The flows involve viscous layers in the interior of the flow domain, as well as boundary layers, and the investigation is unusual in that the position and structure of all the viscous layers are determined uniquely. The note is intended to be an illustration of the principles that lead to this determination, not a source of information of practical value.The flows take place in a two-dimensional channel with porous walls through which fluid is uniformly injected or extracted. When fluid is extracted through both walls there are boundary layers on both walls and the flow outside these layers is irrotational. When fluid is extracted through one wall and injected through the other, there is a boundary layer only on the former wall and the inviscid rotational flow outside this layer satisfies the no-slip condition on the other wall. When fluid is injected through both walls there are no boundary layers, but there is a viscous layer in the interior of the channel, across which the second derivative of the tangential velocity is discontinous, and the position of this layer is determined by the requirement that the inviscid rotational flows on either side of it must satisfy the no-slip conditions on the walls.

Numerical Study of Convective Heat Transfer From Expanding Annular Pipe Flows

2016 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Prandtl Number ◽  
Convective Heat Transfer ◽  
Diameter Ratio ◽  
Wall Heat Transfer ◽  
Reattachment Point ◽  
Transfer Rates ◽  
Pipe Flows ◽  
Annular Pipe

Convective heat transfer from suddenly expanding annular pipe flows are numerically investigated within the steady laminar flow regime. A parametric study is performed to reveal the influence of the annular diameter ratio, k, the Prandtl number, Pr, and the Reynolds number, Re, over the following range of parameters: k = {0, 0.5, 0.7}, Pr = {0.7, 1, 7, 100}, and Re = {25, 50, 100}. Heat transfer enhancement downstream of the expansion plane is only observed for Pr > 1. Peak wall-heat-transfer-rates always appear downstream of the flow reattachment point, in the case of suddenly expanding round pipe flows, i.e. k = 0. However, for suddenly expanding annular pipe flows, i.e., k = 0.5 and 0.7, peak wall-heat-transfer-rates always appear upstream of the flow reattachment point. The observed heat transfer augmentation is more dramatic for suddenly expanding annular flows, in comparison with the one observed for suddenly expanding pipe flows. For a given annular diameter ratio and Reynolds number, increasing the Prandtl number, always results in higher wall-heat-transfer-rates downstream the expansion plane.

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