Theoretical Investigation of Flow Instability in Axial Compressor

The hydrodynamic, acoustic, and thermal mode interactions affect flow instability in turbomachinery. The disturbance field is decomposed into component modes, and their interactions during throttling are analyzed. A theoretical model integrating resolvent analysis and momentum potential theory is established. Resolvent analysis in an axial compressor is validated via rotating inlet distortion experiments and spectral proper orthogonal decomposition. Resolvent analysis captures the flow structure and establishes links between them and resolvent modes. Amplified perturbation structures trigger stall during throttling. Resolvent analysis identifies the most sensitive forcing frequencies along the throttling process. Response modes are divided into hydrodynamic, acoustic, and thermal components based on these frequencies. To clarify the perturbation energy transport mechanisms, the properties and dynamic interactions of component modes in the decomposed fields are analyzed. This reveals that hydrodynamic–thermal interaction is the dominant contributor to total fluctuating enthalpy. Additionally, interactions between hydrodynamic/thermal components and Coriolis acceleration are key drivers of stall inception, especially in amplifying flow instabilities at the tip region.