Abstract
Abstract In the present study, a computational analysis of the flow in a centrifugal blower is carried out to predict a performance and to explain noise characteristics of the blower. Unsteady, 3D Navier-Stokes equations were solved with k- e turbulence model using CFX software. CFD results were compared with the experimental data that is acquired from an experiment conducted with the same blower. The pressure fluctuation in the blower was transformed into the frequency domain by Fourier decomposition to find the relationship between flow behaviors and noise characteristics. Sound pressure level (SPL) which is obtained from wall pressure fluctuation at impeller outlet represents relative overall sound level of the blower well. Sound spectra show that there are some specific peak frequencies at each mass flow rate and it can be explained by flow pattern. Keywords : centrifugal blower, wall pressure fluctuation, flow-induced noise. 1. Introduction The centrifugal blower for a fuel cell electric vehicle (FCEV) is known as a significant part of the source of noise because of its very fast rotating speed and high pressure operating condition. It is known that the cause of noise is strongly related with the flow in a blower, that is to say flow-induced noise. There have been some efforts to understand characteristics of the noise of a blower and to reduce it. An experimental study to explain the sound generation mechanisms by wall pressure fluctuations has been existed and the relation of tip clearance noise and rotating instability signals is discussed (Raitor et al. [2008]). In the field of CFD study, it is well known that large eddy simulation (LES) is more accurate than unsteady Reynolds averaged Navier-Stokes (uRANS) method for predicting features of flow-induced noise (Kim et al. [2010]). But LES must pay very expansive cost. In this study, an attempt to get reasonable prediction of noise characteristics while using uRANS is made. And these CFD results are compared with experimental data (Jeong et al. [2012]). Based on an assumption that wall pressure fluctuation is related to the generation of flow-induced noise , wall
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