半高叶片扩压器对离心压缩机流动性能影响的数值研究

In order to analyz the flow mechanism in the half-vaned diffuser and further improve the working performance of the half-vaned diffuser, the research was conducted on the flow characteristics of the half-vaned diffuser in the centrifugal compressor at different blade heights and positions. Based on the research, the tilted half-vaned diffuser was proposed and its flow characteristics in rotating stall were studied. The three-dimensional computational fluid dynamics(CFD)method was used to simulate the whole operation of centrifugal compressors with different diffusers under steady and transient conditions. The results show that compared with the half-vaned diffuser under design conditions, when the tilted half-vaned diffuser is installed on the hub side, the total static pressure ratio and total static isentropic efficiency are increased by 3.80% and 2.74%, respectively, and when installed on the shroud side, the total static pressure ratio and total static isentropic efficiency are increased by 0.82% and 2.11%, respectively. The results show that the tip clearance flow of the tilted half-vaned diffuser can dissipate the energy of static pressure fluctuation in rotating stall, and the fluctuation amplitude of static pressure in diffuser passages can be reduced from about 50 kPa to about 10 kPa. As a new type of diffuser, the tilted half-vaned diffuser proposed in this paper has better performance than the half-vaned diffuser and has a good application prospect. The results in rotating stall conditions can provide an important reference to the flow character of tip clearance of diffuser blade in flow passage.