Boundary-Layer Dynamics in Wall-Resolved LES Across Multiple Turbine Stages

Modern turbomachinery relies on accurate prediction of the flow and especially the state of turbulence to achieve the required level of performance. Transition, relaminarization, wake interactions, and interrow influence form complex, highly unsteady flow patterns. Large eddy simulation (LES) emerges as a promising method to deliver improved accuracy over Reynolds-averaged Navier-Stokes (RANS) approaches as the major energy-carrying scales are fully resolved. However, for wall-bounded flows, modeling of (parts of) the boundary layer might still be inevitable to keep the computational costs manageable. In this paper, we aim to characterize and analyze the boundary-layer state in such a scenario. We employ the high-order discontinuous Galerkin spectral element method to perform a wall-resolved LES of a stator-rotor-stator cascade (Ma up to 0.65, Re up to 8.0 x 10(5)). The interfaces between the blade rows are treated with a high-order accurate sliding mesh approach. Time-averaged performance characteristics are compared against experimental and numerical data. The temporal evolution of the solution is first assessed through the phase-averaged flowfield at different stator-rotor positions. Subsequently, special emphasis is placed on the spatiotemporal evolution of turbulence near the blade surface. Boundary-layer profile and energy spectra analysis are used to give insight into the turbulence development. This investigation not only reveals the complexities of the boundary-layer dynamics but can also serve as benchmark and reference for evaluation and development of wall-modeled LES approaches for turbomachinery applications.

Automated summary

Modern turbomachinery relies on accurate prediction of flow and turbulence state to achieve performance, with large eddy simulation (LES) offering improved accuracy over Reynolds-averaged Navier-Stokes (RANS) methods. This paper characterizes the boundary-layer state using high-order discontinuous Galerkin spectral element method for wall-resolved LES, comparing performance characteristics with experimental and numerical data. The temporal evolution of the solution and spatiotemporal turbulence near the blade surface are analyzed to provide insights into turbulence development.