Analysis of vortex structure and unstable flow characteristics of centrifugal fan
JIANG Chenlong1,2, LI Enda1, ZHU Xingye1*
1. National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2. Nanjing Forest Police College, Nanjing, Jiangsu 210023, China
Abstract：In order to understand the unsteady flow characteristics in the rotor region of a centrifugal fan. The matching relationship between the non-uniform inlet flow characteristics and the unstable flow in the rotor region was investigated based on the SST k-ω turbulence model. The scale and structure of the vortex in unsteady flow path of the rotor based on vortex dynamics was studied. The results show that under the design flow condition, the rotor area of the centrifugal fan presents obvious non-uniform flow characteristics, which can be divided into stable flow area and blocking area according to the air velocity and flow quality. At the same time, the flow characteristics of the inlet surface of the fan are consistent with the flow characteristics in the rotor region, and the pressure, velocity and inlet attack angle are presented non-uniform distribution. The high-speed air on the inlet surface only scours the flow path in the stable flow area of the rotor, while the low-speed flow on the inlet surface flows to each flow passage through the centrifugal force after passing through the rotor shaft. By using the methods of inlet attack angle, circular rector and tangential velocity, the channel with the most severe vortex size and blockage degree in the rotor area under rated condition is determined, and the vortex structure in the unstable channel is successfully captured by TKE and the vortex core distribution.
