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Abstract

This article reports on the use of modified blade-tip configurations designed with a view to passive noise control in low-speed fans for compact cooling units. The addition of end-plates at the tip of a datum fan blade is shown to have a positive influence on the fan's rotor-only aero-acoustic signature. The aerodynamic effects of the modified blade tips are experimentally tested in a fully ducted configuration in the near field and far field using a correlation technique. The nature of the flow mechanisms in the blade-tip region are correlated with the specific end-plate design features and their role in the creation of overall acoustic emissions is clarified. The noise emitted by the fans is analysed in terms of coherent vortex structures, tip-leakage flow, and noise sources. Differences in human perception of the noise emitted to the environment are also investigated using a dot-pattern visualization. The study concludes that the modified tip configurations have a marked effect on tip-leakage vortex formation by altering the near-wall fluid paths on blade surfaces. The reduction in rotor noise emission is correlated with the control of tip-leakage flows produced by the tip end-plates.

Keywords

industrial fans tip end-plates aeroacoustic signature passive noise control

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References

Ganz

U. W.

Joppa

P. D.

Scharpf

D. F.

, ‘Boeing 18-inch fan rig broadband noise test’ (1998): NASA CR-1998-208704.

Wright

S. E.

, ‘The acoustic spectrum of axial flow machines’ J. Sound Vibr. 45/2 (1976): 165–223.

Cumpsty

N. A.

, ‘A critical review of turbomachinery noise’ J. Fluids Eng. 99 (1977): 278–293.

Nelson

, ‘Reduced-noise gas flow design guide’ (2005): NASA Glenn Research Center Report.

Marcinowski

, ‘Einfluss des Laufradspalts und der Luftfuehrung bei einem Kuehlgeblaese axialer Bauart’ Motortech. Z. 14 (1953): 259–262.

Mugridge

B. D.

Morfey

C. L.

, ‘Sources of noise in axial flow fan’ J. Acoust. Soc. Am. 51 (1972): 1411–1426.

Longhouse

R. E.

, ‘Control tip-vortex noise of axial flow fans by rotating shrouds’ J. Sound Vibr. 58 (1978): 201–214.

Fukano

Jang

, ‘Tip clearance noise of axial flow fans operating at design and off-design condition’ J. Sound Vibr. 275 (2004): 1027–1050.

Kameier

Neise

, ‘Rotating blade flow instability as a source of noise in axial turbomachines’ J. Sound Vibr. 203 (1997): 833–853.

10.

Holste

Neise

, ‘Noise source identification in a prop fan model by means of acoustical near field measurements’ J. Sound Vibr. 203 (1997): 641–665.

11.

Leggat

L. J.

Siddon

T. E.

, ‘Experimental study of aeroacoustic mechanism of rotor-vortex interactions’ J. Acoust. Soc. Am. 64 (1978): 1070–1077.

12.

Mongeau

Thompson

D. E.

McLaughlin

D. K.

, ‘A method for characterizing aerodynamic sound sources in turbomachines’ J. Sound Vibr. 181 (1995): 369–389.

13.

Miles

J. H.

, ‘Procedure for separating noise sources in measurements of turbofan engine core noise’ (2006): NASA/TM-2006-214352.

14.

Schultz

T. J.

, ‘Synthesis of social surveys on noise annoyance’ J. Acoust. Soc. Am. 64 2 (1978): 377–405.

15.

Sottek

Genuit

, Sound quality evaluation of fan noise based on hearing-related parameters. In Proceedings of the Fan Noise 3rd International Symposium 2007.

16.

Corsini

Rispoli

Sheard

A. G.

, ‘Development of improved blade tip end-plate concepts for low-noise operation in industrial fans’ Proc. IMechE, Part A: J. Power and Energy 221 A5 (2007): 669–681 DOI: 10.1243/09576509JPE386.

17.

Corsini

Rispoli

Sheard

A. G.

, A meridional fan (2008): Patent application no. 0800582.9, GB, 14 January 2008.

18.

Inoue

Kuroumaru

Furukawa

, ‘Behavior of tip leakage flow behind an axial compressor rotor’ J. Gas Turbine Power 108 (1986): 7–14.

19.

Corsini

Rispoli

, ‘Using sweep to extend stall-free operational range in sub-sonic axial fan rotors’ Proc. IMechE, Part A: J. Power and Energy 218 (2004): 129–139 DOI: 10.1243/095765004323049869.

20.

Kinghorn

I. R.

Millar

, (2005): FW-RDLab Report r9124.

21.

Corsini

Sheard

A. G.

, ‘Tip end-plate concept based on leakage vortex rotation number control’ J. Comput. Appl. Mech. 8 1 (2007): 21–37.

22.

Fukano

Takamatsu

Kodama

, ‘The effects of tip clearance on the noise of low-pressure axial and mixed flow fans’ J. Sound Vibr. 105 (1986): 291–308.

23.

Bianchi

Sheard

A. G.

Kinghorn

I. R.

Corsini

Rispoli

, Experimental development of a measurement technique to resolve the radial distribution of fan aero-acoustic emissions. In Proceedings of the Fan Noise 3rd International Symposium, 2007.

24.

Laurendeau

Jordan

Delville

Bonnet

, ‘Nearfield-Farfield correlations in subsonic jets: what can they tell us?’ (2007): AIAA paper 2007-3614.

25.

Ribner

, ‘Quadrupole correlations governing the pattern of jet noise’ J. Fluid Mech. 38/1 (1969): 1–24.

26.

Pickover

C. A.

, ‘On the use of symmetrized dot patterns for the visual characterization of speech waveforms and other sampled data’ J. Acoust. Soc. Am. 80 3 (1986): 955–960.

27.

J. D.

Chuang

C. Q.

, ‘Fault diagnosis of internal combustion engines using visual dot patterns of acoustic and vibration signals’ (2005): NDT&E International 38 605-614.

28.

De Rosier

Normand

M. D.

Peleg

, ‘Effect of lag on the symmetrised dot pattern (SDP) displays of the mechanical signatures of crunchy cereal foods’ Sci. Food Agric. 75 2 (1997): 173–178.

29.

Magliozzi

Hanson

Johnson

D. B.

Metzge

F. B.

, ‘Noise and wake structure measurements in a subsonic tip speed fan’ (1973): NASA CR 2323.

30.

Cumpsty

N. A.

, ‘Sum and difference tones from turbomachines’ J. Sound Vibr. 32/3 (1974): 383–386.

31.

Quinlan

D. A.

Bent

P. H.

, ‘High frequency noise generation in small axial flow fans’ J. Sound Vibr. 218 (1998): 177–204.

Detection of aerodynamic noise sources in low-speed axial fans with tip end-plates

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