Aeroacoustic Study of Coaxial Rotor under Varying Trim Conditions and Rotor Orientations using Free Wake Analysis

This paper performs aerodynamic and acoustic analysis on a coaxial rotor system based on the XH-59A coaxial helicopter. The aerodynamic analysis is performed in RCAS using free wake modeling, and the acoustic prediction is performed with PSU- WOPWOP, which utilizes Farassat's Formualation 1A of the Ffowcs Williams-Hawkings equation. The coaxial rotor system is analyzed for forward flight speeds of 100 knots and 150 knots. For each case the rotor shaft angle and the distribution of loading is varied to understand the impact on the rotor noise and the aerodynamic environment of the rotor system. The aerodynamic environment is analyzed by wake and blade load visualization, and the noise is computed on a hemi-spherical grid 10 rotor radii from the coaxial rotor system.