Noise control of a backward-curved centrifugal fan by reducing pressure fluctuations between the impeller and cut-off surface

The noise emitted by the impeller is mainly produced through the pressure fluctuations of impeller and cut-off surface. In this study, it is attempted to minimize the high tonal sound generated by impeller-surface interaction of a backward-curved centrifugal fan. Firstly, the aero-acoustic performance of the two impellers with flat and curved shroud plates is compared inside the fan with the original cut-off. Secondly, the effects of using an open-cell metal foam (OCMF) on the cut-off for both mentioned impellers is examined. From the experimental investigations, it is shown that the impeller with curved shroud plate reduces RMS pressure around 11.7 dB compared to the flat shroud plate. Moreover, employing the OCMF layer (20ppi) on the surface of the cut-off can reduce the RMS pressure around 10.5 dB without significantly reducing outlet flow rate. In general, the modifications are reduced the fan noise by up to 13.7 dB at maximum RPM. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study investigates the impact of different shroud plate structures and the use of open-cell metal foam layer on centrifugal fan noise. Experimental results show that using a curved shroud plate impeller and an OCMF layer on the cut-off surface can effectively reduce fan noise.