Wall-Resolved iLES of Compressor Tandem-Blades Using High-Order DG Method

Abstract The purpose of outlet guide vanes in low-pressure compressors is to redirect the incoming airflow axially. As climate, energy, and environmental goals push for greater efficiency, there is increasing pressure to enhance the performance of modern aeronautical engines, resulting in more extreme flow conditions. However, high flow turning often leads to increased losses and a higher risk of flow separation. Tandem blade designs offer a solution by enabling large flow deviations while helping to maintain flow attachment. This is achieved by making the boundary layer on the rear blade more resilient to separation. Despite these benefits, tandem blade configurations are subject to complex flow phenomena, including interactions between the wake of the front blade and the boundary layer on the suction side of the rear blade, laminar separation bubbles on the front blade, laminar-to-turbulent transition, as well as turbulent mixing and merging of the wakes. These effects significantly influence performance and pose challenges for standard RANS models. This paper investigates the performance of tandem blades using wall-resolved Large-Eddy Simulations (wrLES), offering a detailed comparison with RANS results. Specifically, we present wrLES of a low-pressure compressor tandem blade in a cascade configuration, employing a high-order discontinuous Galerkin method (DGM) to capture the complex flow dynamics.