0
Research Papers: Flows in Complex Systems

Modification of Axial Fan Flow by Trailing Edge Self-Induced Blowing

[+] Author and Article Information
Matjaž Eberlinc

Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, Ljubljana SI-1000, Sloveniamatjaz.eberlinc@fs.uni-lj.si

Brane Širok

Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, Ljubljana SI-1000, Sloveniabrane.sirok@fs.uni-lj.si

Matevž Dular

Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, Ljubljana SI-1000, Sloveniamatevz.dular@fs.uni-lj.si

Marko Hočevar

Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, Ljubljana SI-1000, Sloveniamarko.hocevar@fs.uni-lj.si

J. Fluids Eng 131(11), 111104 (Oct 23, 2009) (7 pages) doi:10.1115/1.4000345 History: Received February 07, 2008; Revised September 28, 2009; Published October 23, 2009

Axial fans often show adverse flow conditions at the fan hub and at the tip of the blade. The modification of conventional axial fan blade is presented. Hollow blade was manufactured from the hub to the tip. It enables the formation of self-induced internal flow through internal passages. The internal flow enters the passage of the hollow blade through the opening near the fan hub and exits through the trailing edge slots at the tip of the hollow blade. The study of the influence of internal flow on the flow field of axial fan and modifications of axial fan aerodynamic characteristics is presented. The characteristics of the axial fan with the internal flow were compared to characteristics of a geometrically equivalent fan without internal flow. The results show integral measurements of performance testing using standardized test rig and the measurements of local characteristics. The measurements of local characteristics were performed with a hot-wire anemometry and a five-hole probe. Reduction in adverse flow conditions near the trailing edge at the tip of the hollow blade, boundary-layer reduction in the hollow blade suction side, and reduction in flow separation were attained. The introduction of the self-induced blowing led to the preservation of external flow direction defined by the blade geometry, which enabled maximal local energy conversion. The integral characteristic reached a higher degree of efficiency.

FIGURES IN THIS ARTICLE
<>
Copyright © 2009 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 5

Average velocity and turbulence intensity in operating point φ1=0.24

Grahic Jump Location
Figure 6

Average velocity and turbulence intensity in operating point φ2=0.26

Grahic Jump Location
Figure 7

Average velocity and turbulence intensity in operating point φ3=0.28

Grahic Jump Location
Figure 8

Phase average of the axial relative velocity field for φ2=0.26 and radius of 228 mm

Grahic Jump Location
Figure 9

Axial, tangential, and radial velocities, and yaw angle α for fan operating point φ1=0.24

Grahic Jump Location
Figure 10

Axial, tangential, and radial velocities, and yaw angle α for fan operating point φ2=0.26

Grahic Jump Location
Figure 11

Axial, tangential, and radial velocities, and yaw angle α for fan operating point φ3=0.28

Grahic Jump Location
Figure 1

Axial fan with self-induced trailing edge blowing: (a) schematic diagram of the axial fan, (b) axial fan, and (c) hollow blade (1. external flow; 2. internal flow; 3. fan rotor; 4. fan casing; 5. inlet opening for internal flow; 6. trailing edge slot at the tip of the hollow blade for internal flow; 7. rotation of the axial fan; 8. hollow blade) (12)

Grahic Jump Location
Figure 2

(a) Direction and size of the internal uj and external w flow velocities at the blade trailing edge; (b) external flow velocity vector triangle on the blade trailing edge: absolute c2, axial ca2, and tangential u velocities

Grahic Jump Location
Figure 3

Comparison of the integral characteristic of the axial fan at local properties and normalized efficiency for the cases with and without internal flow: (◼) total pressure coefficient ψ for the case with internal flow; (●) total pressure coefficient ψ for the case without internal flow; (◻) normalized efficiency η∗ for the case with internal flow; (○) normalized efficiency η∗ for the case without internal flow; (▲) power coefficient λ for the case with internal flow; and (△) power coefficient λ for the case without internal flow

Grahic Jump Location
Figure 4

Measuring station scheme for measuring local flow properties: 1. axial flow fan; 2. axial flow fan mesh; 3. wind tunnel with measured axial flow fan; 4. high-speed camera; 5. rotation direction of axial flow fan; 6. five-hole probe; 7. hot-wire anemometer; 8. inductive sensor; 9. rotational speed sensor; 10. illumination, 11. wind tunnel; 12. flow direction indication; 13. differential pressure transmitter 5; 14. signal conditioning module; 15. positioning table; 16. differential pressure transmitter 1–4; 17. PC for control, acquisition, and data storage 1; 18. axial flow fan with hollow blades and detail; 19. PC for control, acquisition, and data storage 2; and 20. detail (presenting measurement points on a line perpendicular to the axis at a distance of 5 mm behind the trailing edge of the hollow blade)

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