Unsteady Boundary Layer Behavior due to Wake Passing Effects on Low-Speed Linear Cascade Compressor Airfoils With Single and Tandem Configurations: Part 2 - Endwall Flow

Abstract Following the analysis of wake-passing effects on midspan boundary layer behavior in part 1, this study investigates the influence of unsteady inflow on three-dimensional flow phenomena in a highly loaded compressor cascade with contracting endwalls. Single and tandem stator configurations are analyzed using DLR’s CFD solver TRACE, incorporating a rotation-corrected k-ω turbulence model and the γRe™ transition model. The unsteady simulations focus on wake-induced effects on endwall boundary layer behavior, radial performance characteristics, and airfoil boundary layer stability. Results show that the tandem stator exhibits higher endwall losses than the single stator. However, the wake generator redistributes mass flow, stabilizing the endwall boundary layer and reducing near-wall losses. While this effect can improve endwall performance and potentially extend the operating range, the wake also thickens the suction side boundary layer, increasing midspan losses and entropy production. The front vane of the TS behaves similarly to the SS, while the rear vane is less affected by wake-induced losses due to the shielding effect of the FV wake. The study highlights the competing effects of wake impingement on endwall stabilization and midspan boundary layer loading, with implications for compressor efficiency and stall behavior. While the results provide key insights, they remain preliminary due to URANS limitations and the absence of experimental validation.