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.

Detection of aerodynamic noise sources in low-speed axial fans with tip end-plates / S., Bianchi; Corsini, Alessandro; Rispoli, Franco; A. G., Sheard. - In: PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS. PART C, JOURNAL OF MECHANICAL ENGINEERING SCIENCE. - ISSN 0954-4062. - STAMPA. - 223:6(2009), pp. 1379-1392. [10.1243/09544062jmes1277]

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

CORSINI, Alessandro;RISPOLI, Franco;
2009

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.
2009
aeroacoustic signature; industrial fans; passive noise control; tip end-plates
01 Pubblicazione su rivista::01a Articolo in rivista
Detection of aerodynamic noise sources in low-speed axial fans with tip end-plates / S., Bianchi; Corsini, Alessandro; Rispoli, Franco; A. G., Sheard. - In: PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS. PART C, JOURNAL OF MECHANICAL ENGINEERING SCIENCE. - ISSN 0954-4062. - STAMPA. - 223:6(2009), pp. 1379-1392. [10.1243/09544062jmes1277]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/228765
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