Application of an Overset Grid Method to the Large Eddy Simulation of a High-Speed Multistage Axial Compressor

Abstract

The present study aims at evaluating the feasibility and the accuracy of the Large-Eddy Simulation of an actual high-pressure multistage compressor, performed with the TurboAVBP numerical method. TurboAVBP relies on the coupling of several domains via an overset grid method. The latter is demonstrated to keep the order of accuracy of the numerical scheme across six successive rotor-stator interfaces. The simulated configuration corresponds to the 3.5 stage axial compressor CREATE. Three unstructured grids of CREATE, with different resolutions, are generated. They contain 37 blades, the actual rotor tip clearances and a recirculating cavity. The predictions of the global aerodynamic performances and of the radial profiles are found to agree well with experimental data. The analysis of the flow shows that the finest grid exhibits the turbulent flow structures expected in such a configuration, including the blade and vane wakes and the rotor tip leakage vortices.

Comparison of Various CFD Codes for LES Simulations of Turbomachinery: From Inviscid Vortex Convection to Multi-Stage Compressor

“…The numerical parameters of the simulations are detailed in [13], [14]. The CPU cost, directly related to the mesh size and the time step, increases from one order of magnitude from M1 to M2 and M2 to M3, as shown in Table 6.…”

“…Going beyond HPC evaluation, some comparisons with available experimental data have been performed [13], [14], and the main outcomes are recalled here. The turbulent structures simulated by LES are shown in Figure 26 Measured iso-speed characteristic curves of CREATE2bis compressor at 11 543 rpm are shown in Figure 28 and Figure 29 in terms of total pressure ratio and isentropic efficiency respectively.…”

“…Note that close to the tip, the turbulence intensity is underestimated by all simulations, most refined ones being the closest but a clear deficit is still observed. For more analysis of these results, please refer to [13] and [14].…”

Massively Parallel Large Eddy Simulation of Rotating Turbomachinery for Variable Speed Gas Turbine Engine Operation

“…A feasible option is to use wall-modeled LES approach where the viscous sub-layer and the buffer region of the boundary layer are modeled instead of being resolved, substantially reducing the stringent grid requirements. Few studies have utilized WMLES for the numerical analysis of compressors [23][24][25] and turbines [26][27][28]. These studies have focused on the development of accurate physics based modeling tools for predictive design in complex geometries.…”

Comparison of LES and RANS predictions with experimental results of the fan of a turbofan

“…Hah (2009) [11] is among the first to demonstrate the advantages of a pure LES, clarifying a debated issue regarding flow features in the NASA Rotor 37 and showing evident improvement in total loss predictions. Considering industrial computations, Papadogiannis et al (2016) [23,22] validated a wall-modeled LES on a transonic turbine stage, Gourdain (2013) [9] performed a wall-resolved LES on a single-stage axial compressor, and de Laborderie et al (2016) [6] have presented a wall-modeled LES computation of the 3.5 stages CREATE configuration, taking into account technological effects.…”