Abstract
Shock wave/boundary layer interaction (SWBLI) is one of the key factors that limits the improvement of aerodynamic performance and stability for supersonic/transonic compressors. In this research, a combined flow control device (CFCD) was designed for controlling SWBLI in the NASA transonic compressor Rotor 35. The original flow fields for Rotor 35 were numerically analyzed first. The results show that the SWBLI is severe, resulting in much flow loss and partly leading to the compressor instability. Based on this phenomenon, the CFCD was designed with a novel three-dimensional passive self-recirculation flow channel and an active suction slot. The flow channel is mounted on the rotor blade suction surface to connect the low- and high-pressure regions ahead of and behind the shock, respectively. The effect of the CFCD on the rotor performance and corresponding working mechanism are then researched as well. With the help of CFCD, the rotor-achieved total pressure ratio (TPR) is maximally increased by 3.0%, and the stall margin (SM) is improved by 4.1% as well. But the rotor isentropic efficiency (IE) considering additional energy expenditure caused by active suction flow has the maximum increment at choke point of 0.27% and highest reduction at near-stall point of 0.54%. The working mechanisms of CFCD include two aspects: one is forming a stable and low-entropy generated lambda shock wave and the other one is reducing the magnitude of flow separation. The dominant mechanism varies with the rotor working condition and depends on whether the leading-edge shock moves upstream of the passive bleed slot.
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