LES and Hybrid RANS/LES Simulations of Turbomachinery Flows Using High Order Methods

Abstract

The flow within turbomachinery applications is intrinsically complex and unsteady, and involves boundary layer transition, separation and vortices such as tip leakage vortex and wakes. Recent investigations show that Large Eddy Simulation and hybrid RANS/LES methods are required to accurately capture such flows. It is well-known that the numerical dissipation coming from the spatial discretization scheme must not be excessive because it can have a significant influence on the results. The present investigation assesses the impact of upwind spatial discretization scheme AUSM+(P) with high-order MUSCL extension at third- and fifth-order applied to different turbomachinery cases: (i) Large Eddy Simulation (LES) of laminar separation bubble over the high-lift low-pressure turbine airfoil T106C. The present investigation shows that the MUSCL extension to high-order is compatible with no-match boundaries and solution accuracy is not impacted. (ii) Zonal Detached Eddy Simulation (ZDES) of the first rotor of the transonic research compressor CREATE. Since a shock is present near the blade tip, a mixed scheme is developed in order to improve the robustness of the high-order scheme. The spectral analysis shows that the high-order scheme improves the resolution of small vortical structures. (iii) Zonal Detached Eddy Simulation of a fan rotor in order to well predict the broadband noise due the interaction between the fan wake and the OGV. Third and fifth order schemes are compared for both aerodynamic and acoustic purposes. The wake is well captured by the ZDES method and the velocity power spectral density is well predicted with this advanced method.