Improved flow performance of a centrifugal compressor based on pit formation on the notum of the whirligig beetle (Gyrinidae Latreille)

Abstract

Many studies have shown that bionic forms reduce drag through the control fluid medium. In this study, the evenly aligned pits of the whirligig beetle (Gyrinidae Latreille) notum were selected as the bionic form to be studied. They were used in centrifugal compressor impellers, called bionic centrifugal compressors, and the flow characteristics were simulated and compared to the prototype compressor. The simulation results show that compared to the prototype compressor, the pressure drag of bionic centrifugal compressors was reduced dramatically, while the pressure ratio was significantly improved. The pressure drag decreased by 19.24%, while the compression ratio increased by 9.8%. The bionic form of the blade delayed the boundary layer separation of the impeller suction surface, reducing the turbulent kinetic energy loss and improving internal air flow. The effect of drag reduction was shown to have a close relationship with the dimple size and bionic surface area; the greater the area, the better the drag reduction effect. However, there should exist an optimal bionic area, which could be determined by considering the flow velocity inside the impeller.