Numerical Simulation Of The Inner Flow Field In The Centrifugal Fan

The centrifugal fan is a kind of turbomachinery, and the multi-blade centrifugal fan is widely used in engineering because of its high pressure coefficient and low noise. In this paper the inner flow field in the centrifugal fan is numerically simulated and its flow characteristics are analyzed.In the numerical simulation of three-dimensional flow in multi-blade centrifugal fan, the three-dimensional time averaged N-S equation and the RNGk-ε turbulent model are used, Finite Volume Method, non-uniform tetrahedral meshes and the SIMPLE algorithm are selected. In order to improve the quality of meshes and save the computing time or computer EMS memory, the flow field is divided into different blocks and the non-uniform tetrahedral meshes are suitably set up for every block. The standard wall function is adopted the flow near wall, the rotating coordinate system are used to calculate the flow in impeller.The results of simulation show the many important phenomena of the flow in the multi-blade centrifugal fan, such as the vortices in the blade channels, the flow separation at the suction side of the impeller, the second flow in the volute and the "jet-wake" phenomenon at the exit of the blades. Especially, it is found that the inner flow field in the centrifugal fan is asymmetric, i.e. the distribution of the pressure and velocity in all blade channels is not same. The distribution of pressure on the surface of impellers is also obtained.Based on the study of the flow efficiency in different inlet angle of blade and inlet gap of impeller, their influence is found out, and the experiment results shows the simulation is correct. It is useful for the optimal design of the multi-blade centrifugal fan.