Investigation of the flow mechanism of a highly loaded compressor cascade with upstream wakes at the low Reynolds number condition

The development of jet engines for advanced aircraft flying at high altitudes, e.g., unmanned aerial vehicles, has attracted increasing attention to the aerodynamic performance deterioration of highly loaded compressors operating at low Reynolds numbers (Re). Although many flow control strategies have been developed to improve the compressor performance under low Re conditions over the past decades, few researchers have focused on the effect of the inherent compressor rotor-stator (R/S) interactions on the compressor flow fields at low Re conditions. Indeed, the upstream periodic wakes generated by the upstream blades, which are considered the source of high turbulence disturbance, are expected to have the potential to control complex flow phenomena such as downstream blade boundary layer separation and transition. Thus, this paper numerically investigates a highly loaded compressor cascade operating under a typical low Re condition to explore the influence and flow control exerted by R/S interaction. Initially, an appropriate Re condition is chosen to clarify the aerodynamic performance variation of the studied cascade at different Re number conditions. Subsequently, a detailed comparison and analysis of the flow structural changes of the studied cascade with and without the upstream wakes is conducted, and special attention has been paid to the cascade boundary layer transition characteristic. Finally, the upstream wakes' impact and underlying flow mechanism on the studied cascade's boundary layer separation and transition are revealed. The results of this paper proved the potential of upstream wakes for improving flow structures and aerodynamic performance of highly loaded compressors under low Re conditions.