Impact of Dominant Flow Structures on Turbulence Energy in Compressor Corner Separation

Three-dimensional unsteady flow structures of corner separation generate complex turbulent characteristics in compressors. To investigate the dominant flow structures of corner separation and their impact on the transport regimes of turbulence energy, delayed detached eddy simulation is employed to solve the corner separation flow in a highly loaded compressor cascade. The proper orthogonal decomposition (POD) is applied to the unsteady flow, and two dominant unsteady modes are revealed: one is associated with the development of separating vortices, and the other is characterized by low-frequency large-scale features near the end wall. By combining the POD modes with the local trace criterion, the modal vortex structures and their featured vortex swirling patterns are analyzed. By integrating the POD modes with the turbulent kinetic energy (TKE) transport equation under compressible condition, the relationship between the dominant modal structures and the TKE transport mechanisms for the corner separation flow is established. ults show that the vortex developing modes primarily drive the production of TKE and the complex turbulent dif ion, while the low-frequency modes contribute to TKE feedback near the end wall and turbulent diffusion on a croscopic scale within the passage. These findings could provide guidance for turbulence modeling and flow control for compressors.