Effects of a Novel Flow Control Strategy Combined with Slotted Stator and Self-Circulating Casing Treatment on Compressor Aerodynamic Performance

Self-recirculating casing treatment (SCT) is a dependable flow control approach for enhancing the compressor stability. However, the traditional SCT is difficult to inhibit the boundary layer separation in stator passage while expanding the compressor stable working range, resulting in a minimal improvement in the compressor efficiency. To tackle the technical challenge, a novel flow control strategy was devised for a subsonic single-stage axial flow compressor, combining slotted stator and SCT, named JS-SCT. The JS-SCT is marked by the stator having slots where inclined deflectors are placed. This arrangement makes it possible for some of the airflow that passes through the slot to stream out on the stator suction surface (SS), and the other part gets led into the SCT. By employing multi-passage unsteady numerical simulations, this study explored the flow mechanisms by which the JS-SCT impacts the compressor aerodynamic performance. The results indicate that the JS-SCT not only brings about a stall margin improvement (SMI) of 4.9% enhancement, but also raises the peak efficiency by 0.25% and the efficiency at the near stall point by 2.1%. The airflow directed into the SCT restricts the growth of the tip leakage flow (TLF) and averts the leakage vortex from breaking in rotor tip passage. As a result, the compressor stability is enhanced. Meanwhile, the airflow flowing out on the stator SS speeds up the low-energy fluid and suppresses boundary layer separation (BLS). As a consequence, the flow loss inside the stator passage is reduced, and the compressor efficiency is improved.