Abstract:
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.