Open-Rotor Noise Assessment with CFD/CAA Chaining

Abstract

A numerical strategy based upon a coupling of Computational Fluid Dynamics (CFD) and Computational AeroAcoustics (CAA) solvers is set up for open-rotor noise predictions. The method simulates the near field noise, and is possibly followed by an integral method calculation which leads to the far field noise. The goal of such a method is to take into account the mean flow and acoustical installation effects that a chaining restricted to the CFD and the integral method cannot predict at low computational costs. The chaining is assessed on the Airbus Clean Sky generic open rotor configuration, first on the front rotor only, as an isolated single propeller noise evaluation, second on the isolated CROR. In both configurations, the CFD/CAA results relying on freestream uniform flow are first compared to the CFD/Integral method ones for validation. Then, the chaining is performed considering the mean background flow, allowing to observe the effects of the latter on acoustics. In the case of the CROR, these results are compared to experimental measurements. Results are believed to be sensitive to the data injection into CAA, with more or less effects according to the injection technique.