Stability enhancement via a novel slotted circumferential groove with self-recirculation in a transonic compressor rotor

This study investigates the effects of casing treatments on the aerodynamic stability of axial compressors, with a particular focus on combined configurations featuring circumferential grooves and flow recirculation channels. Three-dimensional numerical simulations are conducted using the transonic NASA Rotor 37 as the baseline. Various configurations are evaluated, including circumferential grooves with and without axial slots, as well as flow recirculation channels with different suction and injection locations linked to the grooves. The results demonstrate that a slotted circumferential groove increases both the pressure ratio and the compressor’s operating range by approximately 3%, albeit with a slight reduction in overall efficiency. An evaluation of three injection locations (45%, 65%, and 100% of the blade tip axial chord) reveals that optimal performance is achieved at the 100% axial chord position, which extends the operating range by approximately 59%. In contrast, injection points located closer to the blade leading edge prove less effective due to severe interactions with the passage shock and the accumulation of low-momentum flow within the recirculation channel. Furthermore, the influence of the suction location along the circumferential groove is analyzed at 45%, 50%, and 80% of the groove height. The results demonstrate that the operating range extension remains largely consistent across all three configurations (56%, 60%, and 59%, respectively), indicating that the bleeding position along the groove has no substantial impact on the overall performance. Detailed flow field analyses, including relative Mach number, total pressure, and entropy distributions, confirm that the combined casing treatment effectively mitigates tip flow blockage and delays stall inception. Consequently, the proposed CCT configuration demonstrates significant potential as a flow control strategy for enhancing the aerodynamic stability of transonic axial compressors.