Abstract
The effect of inclined volute tongue on the aerodynamic noise and performance of a centrifugal fan was investigated by experimental test in this article. The present work highlights that the effect of both the clearance and the radius of the volute tongue has an influence on the performance and noise. The experimental tests of various models aim to obtain the aerodynamic noise and performance characteristics of several fan models. First, the experimental results of centrifugal fan performance are tested by the standard test equipment of aerodynamic performance. The experimental results of centrifugal fan aerodynamic noise are measured by the standard test equipment of experimental noise. Our experimental results mainly show that the generation of aerodynamic noise is significantly correlated with the clearance and radius of the volute tongue. Certain geometries of the volute tongue could reduce the noise of the centrifugal fan without decreasing the performance. It is experimentally demonstrated that the high A-weighted sound pressure levels mainly concentrate on a range of from 700 to 7000 Hz frequency by observing the each 1/3 octave band frequency for four fan models. The comparison of aerodynamic noise results also demonstrates that the inclined volute tongue may not only produce a deceasing of about 1.58 dB compared to that of the baseline model. We further obtain that the properly inclined volute tongue not only has positive performance features compared with the baseline model but also effectively controls the broadband frequency noise of single-inlet centrifugal fan.
Highlights
The centrifugal fans are very important equipment widely applied in systems of ventilation and equipment of air conditioning
It is demonstrated that the high A-weighted sound pressure levels mainly concentrate on a range of 700–7000 Hz frequency by observing the each 1/3 octave band frequency for four fan models, which indicates that the vortex street generated by the narrow blade channel of the fan still plays an important role for the fan noise
Effects of inclined tongue volutes on aerodynamic noise and performance characteristics of a centrifugal fan with single inlet and forward blades are investigated by experimental test by changing the clearance and the volute tongue radius
Summary
The centrifugal fans are very important equipment widely applied in systems of ventilation and equipment of air conditioning. People began to pursue a comfortable working environment which requires the decreasing centrifugal fans noise characteristics and improve the aerodynamic performance. The aerodynamic noise dominates in centrifugal fans noise characteristics. Aerodynamic noise of centrifugal fan includes broadband noise caused by the separation of gas at the blade surface and the impeller outlet, and tonal noise due to the periodic impact of rotating blade on air flow. The aerodynamic noise generation of centrifugal fans has caused increasingly widespread concern. Cai et al.[1] investigated that the aerodynamic noise was produced by the pressure fluctuations near the casing wall and the dipole noise played the most dominant role in all fan noise source on the volute tongue surface. Lee et al.[3] proposed the influence of a gap between inlet duct and impeller in a centrifugal fan, which indicates that the gap could enlarge flow
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