Numerical Analysis of the Boundary Layer Behavior of Low-Speed Linear Cascade Compressor Airfoils With Single and Tandem Configurations

A numerical design space study investigates the boundary layer behavior of highly loaded compressor airfoils featuring single and tandem configurations in a low-speed linear cascade with contracting endwalls. The study considers various Reynolds numbers, turbulence intensities, and blade loads. DLR’s CFD solver TRACE is used for the numerical simulations with a rotation-corrected k-ω turbulence model, Low-Mach preconditioning, and the γReΘ transition model. A robust method for evaluating boundary layer parameters is introduced, based on which representative reference airfoils are designed. Laminar flow dominates around the blade for small Reynolds numbers, turbulence intensities, and low boundary layer loading. As Reynolds numbers increase and turbulence levels rise, the transition progresses into the accelerated front portion of the blade’s suction side. The transition behavior and boundary layer development of the rear vane in a tandem configuration depends on the front vane’s boundary layer behavior. Lower Reynolds numbers correspond to increased boundary layer loading, and the presence of a maximum shape factor at the trailing edge varies with turbulence intensity and transition onset, influenced by the blade design. High turbulence intensities and small Reynolds numbers increase boundary layer thickness, affecting the interaction between front and rear vanes in tandem configurations. The entropy production per chord length in the boundary layer rises with decreasing Reynolds numbers and increasing turbulence intensity. The findings emphasize the need for distinct design guidelines for single and tandem configurations, considering the varying Reynolds numbers and boundary layer behaviors.