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 highfidelity 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.