Reducing Effect of Secondary Flows on Axial Compressor Rotor Using Casing Treatment

This study investigates the effectiveness of casing treatment as a passive flow-control technique for mitigating the adverse effects of secondary flow structures on the aerodynamic performance of an axial compressor rotor. Attention is given to tip leakage vortex (TLV) formation, shock-wave interactions, and flow separation phenomena, which are among the primary factors limiting compressor stability and efficiency. The transonic NASA Rotor 37 was selected as the benchmark configuration due to its extensive experimental database and widespread use in compressor aerodynamics research. Computational Fluid Dynamics (CFD) simulations were performed using ANSYS CFX 2023 to evaluate the influence of different casing treatment configurations on compressor performance. The Shear Stress Transport (SST) k–ω turbulence model was employed to accurately capture complex turbulent flow structures, boundary-layer behavior, and shock–vortex interactions occurring near the blade tip region. Three different groove geometries, namely semi-circular, rectangular, and triangular grooves, were investigated and compared with a smooth-casing baseline configuration. In addition, several groove dimensions and arrangements were examined to identify the most effective design for enhancing compressor stability. The numerical results demonstrate that casing treatments significantly modify tip leakage flow behavior, weaken the TLV structure, and reduce blockage formation near the blade tip. These flow-field improvements contribute to a noticeable enhancement in stall margin while maintaining acceptable aerodynamic efficiency levels. Among the configurations investigated, rectangular grooves provided the best overall performance, yielding the highest stall-margin improvement with only a minor reduction in efficiency. The findings highlight the potential of appropriately designed casing treatments to improve compressor stability, delay stall inception, and enhance the operational reliability of high-speed axial compressors. The outcomes of this work provide useful insights for the future design and optimization of advanced turbomachinery systems.