| The flow in the channels of centrifugal blower which consists of inlet, impeller and volute is very complex. In most cases, this kind of flow field is always obtained by calculating the local flow field. At present, with the development of numerical technology and computer, some three-dimensional viscous CFD(Computational Fluid Dynamics) softwares are used in fluid machine to analysis the internal flow. The combination of physical experiments and numerical computations has become one of major ways to analyze flow rules and phenomena in the centrifugal impeller.Applying the SIMPLEC algorithm in Three-dimensional viscous CFD software, multiple reference frame at rotor-stator coupled area in a centrifugal fan which outer dianmeter is 1 meter, and wall function in the computation at near wall, the flow field of centrifugal fan was computed.The distribution of velocity and pressure and temperature in several section of centrifugal blower are partly analyzed and the conclusions are obtained, such as impeller and volute, inlet case, convergence body part. And the facts which affect the efficiency of centrifugal fan were analyzed.The volute is ameliorated basically in this paper. After ameliorating the volute line, the distribution of velocity and pressure in impeller and volute are analyzed, and the results are compared with those of the primary. After ameliorating the volute line, the conclusions of the flow and the pressure distribution are obtained, and are compared with those of the primary. And pressure distribution of the district in 360 degree is more in reason.In the same condition, the error between the first computation and experimentation is less than 5 percent, and validate the reliability of the computation. The total pressure of the centrifugal blower is improved 400Pa averagely and the efficiency is improved 2 percent by changing the line of volute. It provides important numerical evidence for the designment, improvement, and optimization of centrifugal blower.
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