MECHANISM STUDY OF STATOR SUCTION SLOTS TO INHIBIT THE BOUNDARY LAYER SEPARATION IN A SINGLE-STAGE AXIAL FLOW COMPRESSOR

In addressing the flow phenomenon that the starting point of boundary layer separation is located at the stator leading edge, three suction slots with axial positions of 15% Ca, 50% Ca and 85% Ca were designed on NASA Stage35. Four schemes were developed to investigate the effect of different suction slots on the boundary layer separation. The results show that four schemes improve the compressor total performance under the small and medium mass flow rate conditions. Suction-AB scheme, with double slot located at 15% Ca and 50% Ca, improves the total pressure ratio and isentropic efficiency by 0.89% and 1.83% under the near-stall condition, respectively. The internal flow field analysis shows that the slot-B, located at the 50% Ca, plays a key role in inhibiting the boundary layer separation. The airflow inside the separation area only needs to make a minimal directional turn to flow into the slot-B, making it difficult for the boundary layer separation to continue downstream, which is also the reason why the slot-C, located at 85% Ca, is unable to bring more improvements. However, the airflow into the slot-A, located at 15% Ca, requires a bigger directional turn, resulting in a lack of ability in slot-A to inhibit the boundary layer separation.