A numerical study on aeroacoustic effects of main–tail rotor interaction in helicopter configuration

This study presents a numerical investigation into the aeroacoustic characteristics of a helicopter configuration featuring both main and tail rotors operating in subsonic flow. Particular emphasis is placed on analyzing the aerodynamic interaction between the rotors and their impact on noise generation. Unsteady aerodynamic loads on the rotor blades are predicted using a boundary element-based panel method, which accurately captures the complex flow structures around the rotating blades. The resulting surface pressure distributions are subsequently used as input for an acoustic prediction model based on the Ffowcs Williams-Hawkings (FW-H) equation to evaluate far-field noise radiation. The results reveal that the aerodynamic interaction between the main and tail rotors significantly influences both the aerodynamic performance and noise emission characteristics. Specifically, this interaction modifies the unsteady loading patterns, leading to pronounced variations in sound pressure levels and noise directivity in both hover and forward flight conditions. The findings provide valuable insights into the aeroacoustic behavior of interacting rotor systems and support the development of more effective noise reduction strategies in helicopter design.