Theoretical and experimental studies on the noise control of centrifugal fans combining absorbing liner and inclined tongue

In previous work, it has been validated that the inclined tongue has a significant effect on controlling the tonal noise of centrifugal fans. In order to reduce the broadband noise of centrifugal fans, theoretical and experimental research studies have been implemented to study the effect of the sound-absorption volute on noise propagation. First, a mathematical-physical model of the sound-absorption volute is established to explore the influence of the sound-absorption coefficient of the liner, which is dependent on the liner thickness, cavity depth, etc. Then, an experimental study is carried out to measure the coupling effect between the absorbing liner and the inclined tongue and its potential for the noise control of centrifugal fans. The experimental results agree well with the theoretical result, and validate the mathematical-physical model, proving it a practical model for further optimization of the sound-absorption volute. In addition, the results indicate that considerable noise reduction can be achieved by combining both the posed absorbing liner and modified inclined tongue.