Large-Eddy Simulation of a rotor tip-clearance flow

Kurzfassung

Tip-leakage flows constitute a major concern for turbomachine performances, stability and broadband noise generation. A large-eddy simulation (LES) of a rotor blade is here presented and compared to experimental data from DLR. A particular attention is paid to the flow configuration of the simulation. The simulation of the inlet duct allows to recover accurately the flow conditions at the fan face. Downstream of the rotor, a detailed analysis of the mean velocity and turbulence intensity is carried out: 2D flow maps, radial profiles of azimuth-averaged variables and wake parameters are plotted. The focus point of the present study is the complex tip-gap flow, and LES is shown to reproduce remarkably the experimental data in this region. These results are achieved in spite of a spurious separation that occurs on the blade suction-side and affects the lower radii (mid-span and hub regions). Finally, the velocity spectra computed by LES in the tip region are in very good agreement with the experimental data. The broadband content is accurately simulated over the whole experimental range of frequencies.