Near real-time simulation of rotorcraft acoustics and flight dynamics

In this paper, a near-real-time rotorcraft flight dynamics-acoustics prediction system is presented. The high-fidelity PSU-WOPWOP rotor noise prediction code is coupled with the GENHEL flight simulation code, which provides low-fidelity blade loading and motion. This system is an initial step intended to investigate the feasibility of real-time rotorcraft noise prediction and to demonstrate the utility of such a system. Limited acoustic validation is shown for a contemporary-design four-bladed main rotor in level flight. A complex 80-s maneuver was used to demonstrate the potential of the coupled system. This realistic maneuver includes a climb, coordinated turn, and level flight conditions. The noise predictions show changes in main rotor noise radiation strength and directivity caused by maneuver transients, aircraft attitude changes, and the aircraft flight - but do not include the effect of blade-vortex-interaction noise. A comparison of the total noise with the thickness and loading noise components helps explain the noise directivity. The computations for a single observer were very fast, although the algorithm is not currently organized as a real-time computation.