Flow loss mechanisms and optimization methodology for a compressor bleed slot

Inter-stage bleed in compressors serves critical functions in aircraft environmental control, engine inlet anti-icing, and cooling of engine hot-end components, thereby ensuring the safety and efficient operation of both aircraft and engines. Consequently, minimizing inter-stage bleed losses and enhancing bleed efficiency have become central challenges in the refined design of high-performance compressors. Building on the typical flow characteristics of the bleed slot, this study classifies the internal flow into three sections: the turning section, the diffusion section, and the sudden expansion mixing section. The flow and loss mechanisms of the primary components of the bleed system are elucidated, covering four aspects: flow separation in the turning section, local separation induced by incidence angle, excessive diffusion induced flow separation, and losses arising from sudden expansion mixing. Targeted flow control strategies are proposed for each of these loss mechanisms to improve the internal flow within the bleed system and thereby mitigate losses. Based on the loss mechanisms and corresponding optimization strategies, a novel optimization design methodology for the bleed slot is proposed, which enables parametric profiling of the slot’s turning and diffusion sections, respectively. Finally, the methodology was applied to optimize four bleed slots with different overall design parameters, and the optimized configurations were experimentally compared with conventional straight-line and current high‐performance quadratic polynomial profiles. The results confirm the effectiveness of both the proposed optimization strategies and the optimization design methodology,K