Influence of the Tip Winglet Structure Modeling on Leakage Flow at a High-Load Compressor Stage

Abstract

Abstract Tip winglet technology is an effective method for increasing the stable operating range of compressors. This paper examines six types of pressure-side tip winglets with varying circumferential widths and chord lengths, to assess their influence on the stability expansion ability and flow structure of the compressor stage. The effectiveness of stability expansion via tip winglets is enhanced with increased tip winglet width. Specifically, when the tip winglet width reaches twice that of the rotor blade tip width, the stable operating margin improvement can attain 11.43%. Moreover, when the tip winglet width is 1.5 times the rotor blade tip width, the full-chord tip winglet yields the most significant stability expansion effect, surpassing that of partial-chord length tip winglets. Tip winglets mitigate the leakage mass flow rate by balancing the mismatch in flow velocity components, exacerbating leakage flow deterioration. Concurrently, the degree of leakage vortex fragmentation is weakened, controlling the accumulation of low-energy fluid within the passage. Furthermore, tip winglets prevent the concentration of low-energy fluid in the radial region, effectively enhancing the flow structure and stability of the compressor. When designing the tip winglet structure, it is crucial to maximize the stable operating margin of the compressor stage without compromising efficiency. To this end, extending the blade into the passage from the 90% chord to the rotor trailing edge should be avoided.