The present paper is aimed at studying the spectral properties of the tonal noise generated by axial flow fans. The phase of the acoustic pressure FFT is considered as a means to integrate the usual plots of SPL at BPF harmonics. Four different configurations of a fan, obtained combining an upstream bar and a downstream stator in presence of large inlet turbulent structures, have been tested in a hemi-anechoic chamber. In order to vary the strength of the acoustic source, measurements are taken during rotational speed ramps at low angular acceleration. The joint analysis of SPL and phase at BPF harmonics shows that it is possible to distinguish between tonal noise due to inlet turbulence from the tonal noise due to rotor-stator aerodynamic interaction. Furthermore, information about the presence of important propagation effects, which result in a non linear phase trend, may also be gained.

An experimental investigation of the spectral properties of the tonal noise generated by axial flow fans with and without rotor-stator aerodynamic interaction

CANEPA, EDWARD;CATTANEI, ANDREA;MAZZOCUT ZECCHIN, FABIO
2013

Abstract

The present paper is aimed at studying the spectral properties of the tonal noise generated by axial flow fans. The phase of the acoustic pressure FFT is considered as a means to integrate the usual plots of SPL at BPF harmonics. Four different configurations of a fan, obtained combining an upstream bar and a downstream stator in presence of large inlet turbulent structures, have been tested in a hemi-anechoic chamber. In order to vary the strength of the acoustic source, measurements are taken during rotational speed ramps at low angular acceleration. The joint analysis of SPL and phase at BPF harmonics shows that it is possible to distinguish between tonal noise due to inlet turbulence from the tonal noise due to rotor-stator aerodynamic interaction. Furthermore, information about the presence of important propagation effects, which result in a non linear phase trend, may also be gained.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11567/577926
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