Title : Aerodynamics of Tip Leakage flow control in NASA Rotor 37 and its Mitigation
Abstract:
The aerodynamic performance and stability of transonic axial compressors are highly sensitive to tip leakage flows that originate from the pressure differential across the blade tip. These flows generate vortical structures near the endwall, leading to efficiency loss, pressure ratio reduction, and premature stall. The present work focuses on NASA Rotor 37, a widely benchmarked single-stage transonic axial compressor, to investigate tip leakage flow dynamics and their mitigation. Numerical simulations were performed using a validated computational fluid dynamics (CFD) framework, with results compared against experimental data to ensure accuracy. A grid independence study was conducted to establish the robustness of the solution. The influence of varying tip clearance heights was analyzed to determine their impact on pressure ratio, efficiency, and leakage vortex strength. Results confirm that larger tip clearances intensify leakage vortices, degrade aerodynamic performance, and accelerate stall inception. To address these limitations, circumferential casing grooves were employed as a passive flow control strategy. Multiple groove configurations were evaluated to suppress leakage vortex development, delay stall, and extend the operating range. The findings reveal that optimized casing treatment significantly improves stall margin, with only a marginal penalty in peak efficiency. Overall, the study provides valuable insight into tip leakage flow mechanisms and demonstrates that a combined approach of tip clearance optimization and casing treatment can effectively enhance the aerodynamic performance and stability of transonic compressors such as NASA Rotor 37.
