0
Research Papers: Flows in Complex Systems

Turbulent Flow Structure and Swirl Number Effect in a Cyclone

[+] Author and Article Information
X. W. Wang, Y. Zhou

 Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong; Key Laboratory of Manufacture and Test Techniques for Automobile Parts,  Chongqing University of Technology, P. R. China Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong e-mail: mmwowong@inet.polyu.edu.hk

W. O. Wong1

 Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong; Key Laboratory of Manufacture and Test Techniques for Automobile Parts,  Chongqing University of Technology, P. R. China Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong e-mail: mmwowong@inet.polyu.edu.hk

1

Corresponding author.

J. Fluids Eng 133(11), 111103 (Oct 27, 2011) (10 pages) doi:10.1115/1.4005139 History: Received December 17, 2010; Revised August 23, 2011; Published October 27, 2011; Online October 27, 2011

The turbulent flow within a cylinder‐on‐cone cyclone is highly three‐dimensional and our knowledge of this flow has yet to be improved. This work aims to improve our understanding of the flow structure, with special attention to the swirl number effect. The three velocity components of the flow were measured using LDA and PIV. The Reynolds number, based on the inlet velocity and the cyclone cylindrical chamber diameter, was 7.4 × 104 , and the swirl number examined was from 2.4 to 5.3. Three regions of the flow have been identified after careful analysis of the data, which are referred to as the core, the outer and the wall‐affected regions, respectively; each is distinct from another in terms of the vorticity concentration, frequency of quasi‐periodical coherent structure, the probability density function, and mean and variance of velocities. It has been found that the flow, including its Strouhal numbers and radial distributions of the mean and fluctuating velocities, depends considerably on the swirl number.

FIGURES IN THIS ARTICLE
<>
Copyright © 2011 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 2

Dependence of (αn-α1000)/α1000, where α is V¯θ or vθ,rms , on the number n, of PIV images. Measurement location is at r/R = 0.5 and θ = 120°, as marked by symbol +.

Grahic Jump Location
Figure 3

The radial distributions of (a) the LDA-measured mean tangential velocity V¯θ*, (b) mean axial velocity V¯z*, (c) rms tangential velocity vθ,rms*, (d) rms axial velocity vz,rms*S = 2.4, Re = 74000, z/R = 1. Three distinct regions may be identified, viz. the vortex core region (I), the outer region (II), and the wall-affected region (III).

Grahic Jump Location
Figure 10

The radial distribution of (a) the LDA-measured mean tangential velocity V¯θ*, and (b) rms tangential velocity vθ,rms* at different swirl number. Re = 7.4 × 104 , z/R = 1.

Grahic Jump Location
Figure 1

(a) Schematic of experimental setup and the definition of the coordinate system; (b) sketched mean flow (length unit in mm); (c) the top view of the cyclone where X-X indicates the path the LDA probe was traversed across.

Grahic Jump Location
Figure 4

Iso-contours of (a) mean tangential velocity V¯θ* (contours interval Δ = 0.12), (b) mean radial velocity V¯r* (0.039), (c) rms tangential velocity vθ,rms* (0.035), (d) rms radial velocity vr,rms* (0.029), and (e) Reynolds shear stress vθvr¯* in the (r, θ)-plane (3.0 × 10−4 ). (f ) Averaged velocity vectors. Re = 7.4 × 104 , S = 2.4, z/R = 1.

Grahic Jump Location
Figure 5

Iso-contours of (a) the magnitude of averaged vorticity |Ωz¯(2R/Vin)| contour interval Δ = 4.8) and (b) RMS vorticity ωz,rms* in the (r, θ) plane (Δ = 2.4), Re = 7.4 × 104 , S = 2.4, z/R = 1

Grahic Jump Location
Figure 6

The probability density function, p, of the instantaneous circumferentially averaged tangential velocity V∧θ* (a) r/R = 0.2, (b) 0.65, (c) 0.85. S = 2.4, Re = 74000.

Grahic Jump Location
Figure 7

The probability density function, p, of the instantaneous circumferentially averaged radial velocity V∧r*. S = 2.4, Re = 7.4 × 104 , (a) r/R = 0.2, (b) 0.5, (c) 0.85.

Grahic Jump Location
Figure 8

Dependence on r/R of skewness Sk of the instantaneous circumferentially averaged velocities V∧θ and V∧rS = 2.4, Re = 7.4 × 104 , z/R = 1

Grahic Jump Location
Figure 9

Dependence on r/R of flatness F of the instantaneous circumferentially averaged velocities V∧θ and V∧r. S = 2.4, Re = 7.4 × 104 , z/R = 1.

Grahic Jump Location
Figure 13

Dependence of Strouhal numbers (St) on the swirl number (S) in the cyclone flow

Grahic Jump Location
Figure 11

Dependence of Tvθ=12(1N1∑i=1i=N1vθ,rms(ri/R)Vin+1N2∑i=1i=N2vθ,rms(ri/R)Vin) on S, where r1 /R (= 0.25) ≤ri /R ≤rN 1 /R (= 0.68) or r1  /R  (= − 0.68) ≤ri  /R rN 2  /R  (= − 0.25) corresponds to the outer region. Re = 7.4 × 104 .

Grahic Jump Location
Figure 12

Power spectral density functions Evθ of vθ , measured along X-X (Fig. 1c) in the (r, θ) plane (z/R = 1), at various r /R using LDA. (a) S = 2.4, (b) 3.0, (c) 4.3, (d) 5.3. Re = 7.4 × 104 .

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In