Detached Eddy Simulation: Recent Development and Application to Compressor Tip Leakage Flow

Abstract

Detached Eddy Simulation (DES) and its variants are emerging tools for turbomachinery simulations. In this paper, the state-of-the-art upgrades of DES are reviewed, and their capabilities in predicting compressor tip leakage flow are discussed. The upgrade with the best potential is identified as the Delayed DES (DDES) method with the grid spacing FKHΔhyb, which unlocks the physics of the Kelvin-Helmholtz instability in compressor tip leakage flow. The upgraded grid spacing FKHΔhyb is compared against the widely used default one Δmax in a backward-facing step and a low-speed axial compressor rotor. Results show that the DDES method with FKHΔhyb predicts both the main flow field and the turbulence field with reasonably good accuracy. However, the original DDES method with Δmax predicts a delayed transition to turbulence, which leads to an inaccurate prediction of the main flow field when using a coarse mesh. The findings in this paper highlight the future opportunities for using the DDES-FKHΔhyb method to predict tip-driven compressor stall and generate a turbulence database for turbulence model development.

Non-Intrusive Flow distortion measurements within a Turbofan Intake (NIFTI)- De-risking the test campaigns with CFD analysis

“…The second-order implicit time integration scheme is applied for temporal discretization. For simulation of turbulent flows, the standard Spalart-Allmaras turbulence model [Spalart, and Allmaras, 1994] and its variants [He et al, 2020] are available for the RANS branch, and the standard DDES method [Spalart et al, 2006] and its upgrades [He et al, 2021] are available for the hybrid RANS/LES branch. Validations of HADES can be found in previous works [He et al, 2020;He et al, 2021].…”

“…For simulation of turbulent flows, the standard Spalart-Allmaras turbulence model [Spalart, and Allmaras, 1994] and its variants [He et al, 2020] are available for the RANS branch, and the standard DDES method [Spalart et al, 2006] and its upgrades [He et al, 2021] are available for the hybrid RANS/LES branch. Validations of HADES can be found in previous works [He et al, 2020;He et al, 2021]. The computations carried out in this paper use the RANS/URANS mode of the solver by using the SA turbulence model.…”

“…In future studies DDES will be used in the intake to model inherently unsteady nature flow in the intake. The performance of the DDES in this code is shown in [He et al, 2020;He et al, 2021].…”