Research Papers

Improvement of Stalling Characteristics of an Axial-Flow Fan by Radial-Vaned Air-Separators

[+] Author and Article Information
Nobuyuki Yamaguchi, Masayuki Ogata

 Meisei University, 2-1-1 Hodokubo, Hino-shi, Tokyo 191-8506, Japan

Yohei Kato

 Japan Filter Technology, Ltd., I-1-1, Aza Sugise, Tsuhata-machi, Kawakita-gun, Ishikawa Prefecture 929-0454, Japan

J. Turbomach 132(2), 021015 (Jan 13, 2010) (10 pages) doi:10.1115/1.3104612 History: Received September 05, 2008; Revised November 27, 2008; Published January 13, 2010; Online January 13, 2010

An improved construction of air-separator device, which has radial-vanes embedded within its inlet circumferential opening with their leading-edges facing the moving tips of the fan rotor-blades so as to scoop the tip flow, was investigated with respect to the stall-prevention effect on a low-speed, single-stage, lightly loaded, axial-flow fan. Stall-prevention effects by the separator layout, relative location of the separator to the rotor-blades, and widths of the openings of the air-separator inlet and exit were parametrically surveyed. As far as the particular fan is concerned, the device together with the best relative location has proved to be able to eliminate effectively the stall zone having existed in the original solid-wall characteristics, which has confirmed the promising potential of the device. Guidelines were obtained from the data for optimizing relative locations of the device to the rotor-blades, maximizing the stall-prevention effect of the device, and minimizing the axial size of the device for a required stall-prevention effect, at least for the particular fan and possibly for fans of similar light-load fans. The data suggest the changing internal flow conditions affected by the device conditions.

Copyright © 2010 by American Society of Mechanical Engineers
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Figure 12

Effects of opening widths of the inlet and exit of air-separators on the improvement index BS with respect to stalling flow for g/S=0.4, Za=35 mm, and W=33 mm

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Figure 2

The exit guide-vanes and the driving electric motor

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Figure 10

Effects of relative locations of the air-separator Type A (S=37.5 mm, C=30 mm, W=33 mm, and b=25 mm)

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Figure 11

Fan characteristics affected by inlet opening widths S for a constant exit opening width C=18 mm for air-separator Type A, g/S=0.4, Za=35 mm, and W=33 mm

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Figure 13

A survey on tendency in stall improvement from SW stall point to AS stall point achieved by air-separators including axial-vane type and radial-vane type for axial-flow fans of axial-inlet type bladings. (a) Total-to-static characteristics. (b) Total-to-total characteristics. (Sources) MI and MII: Ref. 5, AEM: Ref. 6, MK: Ref. 8, ZME: Ref. 7, N: ( ∗) Ref. 13, MS: ( ∗) present report or Ref. 19, and MY: ( ∗) Ref. 9. Together with in-house data of Mitsubishi Heavy Industries, Ltd. Here, ( ∗) attached above shows results for radial-vaned AS, and none (without ( ∗)) for axial-vaned AS.

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Figure 3

Test facility of the fan

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Figure 4

Original dimensions of the studied fan and the air-separator device

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Figure 5

Rectifying radial-vanes of air-separator Type A

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Figure 6

Fan performance characteristics in the solid-wall condition and reference points

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Figure 7

Comparison of fan performances for conditions with the best air-separator (Type A, S=37.5 mm, C=30 mm, W=33 mm, and g=22.4 mm) and for the conditions with the solid wall

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Figure 8

Variable dimensions of the studied air-separator

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Figure 9

Comparison of fan performances by air-separator Type A for various relative locations g/Za (S=37.5 mm, C=30 mm, W=33 mm, and b=25 mm)

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Figure 1

The rotor mounted together with the air-separator device



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