The rotating stall precursor is a major research focus in the field of aerodynamic compressor flow stability, as an accurate understanding of its physical mechanisms can help improve the operating margin of the compressor system in aircraft engines and ensure flight safety. With advances in numerical simulation techniques, the physical essence of spike-type stall has been increasingly investigated in depth. Many studies assume that weak-amplitude disturbances exist prior to stall and facilitate its onset; however, the specific nature of these disturbances, their relationship with the spontaneous unsteady behavior of the flow, and whether these disturbances serve as the origin of the spike-type stall, have yet to be clarified.
For many years, the field of aerodynamic compressor flow stability has been dedicated to addressing the challenge of rotating stall at low mass flow rates. The research has now advanced to uncovering the physical mechanisms underlying the widely observed stall precursors and developing targeted flow stabilization strategies. With the continuous improvement in computational capabilities, Reynolds-averaged stress (RANS) methods have been widely employed in numerical simulations to capture compressor stall phenomena. Utilizing such methods, the academic community has gained a clearer understanding of the stall process, particularly the flow structure, and it is now generally recognized that radial vortices are the main cause of the spike-type signals. However, this understanding resembles more a state description, and so far, no dynamic depiction of the emergence of stall precursor signals from an initially stable state has been reported. In fact, extensive experimental measurements reveal that almost all axial compressors exhibit a wealth of disturbances near the stall condition. According to the small-disturbance theory in compressor stability, weak disturbances can be amplified in a system at its critical state, leading to instability. Therefore, under real physical conditions, could these widely existing disturbances be the origin of stall precursors?
Recently, the compressor flow stability team led by Professor Tianyu Pan at Beihang University reported for the first time the physical nature of disturbances and the stall evolution process in a compressor cascade using large-eddy simulation (LES). This work not only revealed the concept and physical origin of disturbances in compressor flow stability but also explored the necessary conditions for these disturbances to develop into spike-type stall, and accordingly proposed several indicators for assessing the stability limits.
The team published their work in the Chinese Journal of Aeronautics on March 17, 2025.
"In this study, we found that the LES captures the generation, circumferential propagation, and dissipation of disturbances at high mass flow conditions in a NACA65 cascade, while the RANS yields disturbance amplitudes an order of magnitude lower than LES, and almost no disturbance generation or dissipation is observed. This indicates that scale-resolving methods are essential for accurately capturing compressor flow disturbances. Further investigation reveals that the dynamic behavior of the suction surface shear layer is the physical essence of the complex disturbance dynamics: the shear layer can thicken to generate disturbances or thin to block their propagation. This unsteady behavior introduces additional randomness into the disturbance development," stated Prof. Tianyu Pan and his PhD. student Teng Li of Beihang University. In the stall research, Prof. Pan noted that disturbance amplitudes gradually increase during propagation until they evolve into stall precursors. This study attributes the growth of disturbances to the reduced convective capacity of the mainflow over low-velocity regions, and accordingly proposes several factors to characterize the stability limit of cascade flow.
Although this paper provides unique physical insights into the scale of turbulence and stall in compressor cascades, it is challenging to directly extend these findings to real compressors. On the one hand, real compressors exhibit three-dimensional complex flows—such as tip leakage flow and corner vortices—whose specific disturbance characteristics remain unclear. On the other hand, due to current computational limitations, applying LES to high Reynolds number and high Mach number aero-compressors is nearly impossible. Therefore, Prof. Pan emphasized that the team's next priority is to develop scale-resolving numerical methods suitable for high-load axial compressors, thereby enabling high-fidelity simulations of the complex flow fields in real compressors.
Other contributors include Zhaoqi Yan, from the Research Institute of Aero-Engine at Beihang University in Beijing, China; Qiushi Li from the Key Laboratory of Fluid and Power Machinery at Xihua University in Chengdu, China.
Original Source
Tianyu PAN, Teng LI, Zhaoqi YAN, Qiushi LI. Investigation of turbulence-induced disturbances and their evolution to stall onset in a compressor cascade using large eddy simulation [J]. Chinese Journal of Aeronautics, 2025, https://doi.org/10.1016/j.cja.2025.103491.
About Chinese Journal of Aeronautics
Chinese Journal of Aeronautics (CJA) is an open access, peer-reviewed international journal covering all aspects of aerospace engineering, monthly published by Elsevier. The Journal reports the scientific and technological achievements and frontiers in aeronautic engineering and astronautic engineering, in both theory and practice. CJA is indexed in SCI (IF = 5.7, Q1), EI, IAA, AJ, CSA, Scopus.
