Parallel Large-Eddy Simulation of Subsonic and Transonic Flows with Transition in Compressor Cascade

Laminar–turbulent transition plays a critical role in the aerodynamic performance of compressors and is sensitive to flow conditions and external disturbances. In the present work, a parallel large-eddy-simulation solver is developed and applied to investigate the effects of free-stream turbulence on the mode and location of transition on the blade suction surface of a compressor cascade under subsonic and transonic conditions. Both the parallel accuracy and efficiency of the solver are demonstrated. The transition location is observed to shift upstream as the free-stream turbulence level increases at both the subsonic and transonic conditions. Moreover, increasing the free-stream turbulence level from 0 to 4% causes the transition mode to change from Kelvin–Helmholtz instability-induced transition to bypass transition in the case of subsonic flow, whereas transition occurs in a Kelvin–Helmholtz instability-induced mode even at a high free-stream turbulence level of up to 7% in the case of transonic flow. The work demonstrates the ability of the parallel large-eddy-simulation method to capture the transitional-flow structures in compressor cascades and its potential application to the analysis and design of advanced compressor.