Prediction of Noise Sources in Axial Compressor from URANS Simulation

As part of a larger aeroacoustic study focused on rotor-stator interaction noise, the unsteady flow in a single-stage axial compressor is achieved by a numerical Reynolds-averaged Navier-Stokes simulation. The flowfield is precisely analyzed and assessed by comparing it with available experimental and numerical data. Specifically, the rotor wakes correctly agree with previous laser Doppler anemometry measurements. The unsteady flow, especially the potential effects created by the stator vanes, is then investigated, showing that the stator potential field is responsible for a major secondary tonal noise source on the rotor blades. The rotor wake velocity and turbulent content correspond to the excitations for tonal and broadband noise, respectively. They are greatly influenced by the vane potential effects and, to a lesser extent, by their convection with the mean flow. Two methods of extraction are surveyed along the whole span, showing the need to consider the blockage induced by the stator on the wakes. Finally, the realistic tonal acoustic sources of rotor-stator interaction extracted in time on the stator vane surfaces show a noise mechanism mainly driven by the leading edge and some significant variations from hub to tip.