Advanced Methods for Assessing Flow Physics of the TU Darmstadt Compressor Stage: Part 1 - Transitional Delayed Detached-Eddy Simulation

Abstract

In this first paper of the two-part series, we analyze the predictive quality of transitional Delayed Detached-Eddy Simulation (DDES) for the transonic TU Darmstadt (TUDa) compressor stage. Initially, we validate the DDES in a translational configuration of the compressor at reduced rotational speed. Here we compare DDES results with previously published Large-Eddy Simulation (LES), steady and unsteady Reynolds-averaged Navier-Stokes (RANS) simulations. As the application of the DDES shows noticeable improvements for the shock boundary layer interaction (SBLI) and resulting laminar-to-turbulent transition, we continue analyzing the fully 3D setup. For this configuration, two operating conditions (aerodynamic design point (ADP) and near stall) are considered. We show DDES results and compare them to steady and unsteady RANS simulations, and experiments where available. Although the DDES indicates some improvements at the ADP, RANS is also able of predicting integral turbomachinery performance quantities. However, steady and unsteady RANS fail to predict the flow field with satisfying accuracy at near stall conditions. Especially in separated regions, DDES proves its strength by resolving relevant turbulent structures, which yields noticeably improved results. We discuss reasons for that and highlight the potential of transitional DDES.