Computational Acoustic Prediction on the Aerodynamic and Acoustic Rotorprop Test

This paper investigates the interactional aerodynamics and acoustics of three pusher propeller configurations from the Aerodynamic and Acoustic Rotorprop Test (AART), which were tested in the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel at NASA Ames Research Center. The three CFD simulation models - isolated propeller, full-wing/propeller, and half-wing/propeller - are simulated using the multi-disciplinary rotorcraft simulation tool CREATE™-AV Helios. Unlike the previous work in which the acoustics were simulated using PSU-WOPWOP, in the current work, acoustic prediction is carried out using NASA's acoustic prediction software AARON/ANOPP2. No significant difference is found between the two acoustic solvers for all configurations. The current isolated propeller and full-wing/propeller simulations, which include the nacelle behind the propeller and the actual hub from the experiment, are compared with the previous simulations that had a notional hub and did not model the nacelle. The current and previous simulations show similar acoustic predictions, except that the presence of the nacelle induces additional high-frequency acoustic pressure oscillations but of small magnitudes. All simulations are also compared with measurements. While the full-wing/propeller simulations match well with the measurements, the isolated propeller and half-wing/propeller simulations show discrepancies. The half-wing/prop simulation overpredicts the overall sound pressure level up to 5 dB, which requires further investigations.