Spectral Characterizations of Centrifugal Fan Noise via uRANS-based Noise Prediction Method

F2 -Tonal Noise Modelling

Centrifugal fans are used in a wide range of industrial applications due to the ability to generate high pressure differences and large capacity of mass flow, considering the size. Nowadays, there are numerous studies on the impeller-diffuser interactions and the resulting tonal noise. Prediction of generated noise in centrifugal fan is so complex due to its three-dimensional internal passages, turbulent flows inside, and the flow separations.
As far as prediction of fan noise is concerned, it is important to realize that the far-field acoustics are very much dominated by the internal pressure fluctuations created by the fan inside the housing. For this reason, accurate predictions of the internal pressure fluctuations are crucial and can be used for estimating and analyzing the fan noise characteristics.
In the present work, a prediction method based on uRANS approach is utilized to predict aerodynamics performance and noise characteristics of the centrifugal fans, primarily comprised of impellers, diffusers return channels, and electric motor coils.
The present approach is first validated by the experimental results in aspects of hydrodynamic fan efficiency and sound pressure level spectrum of fan for different air flow rates.
In addition, to reduce the noise, we introduced splitter, as a flow guidance device, and applied between the impeller blades at the inlet of flow passage for various study cases. Using splitter, it is shown a significant improvement in noise reduction of overall sound pressure level and tonal noise generated by impeller diffuser interaction.