A numerical analysis method was applied to investigate aerodynamic noise sources in an industrial centrifugal fan with forward swept blades and the increased volute width. In this method
a three-dimensional unsteady viscous flow in the centrifugal fan was calculated. The intensity of the dominant aerodynamic noise source was qualitatively obtained according to the static pressure change rate at the dominant field in the vicinity of the volute tongue. Numerical results show that increasing the volute width in a certain range can effectively lower the dipole-type discrete noise source level. Based on the numerical analysis
an experiment was conducted to study the influence of the volute width on the aerodynamic performance and the aerodynamic noise. The experiment results show that the numerical method applied in this work provides a good qualitative prediction of the noise change generated by the dipole source. With the increase of the volute width
the blade passing frequency levels of the modified fans decreased by about 3-5 dB(A)at the best efficiency point
while the broadband noise levels increased slightly. It seems that the overall noise characteristics and the aerodynamic performance can be improved.
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references
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