This paper deals with the aeroacoustic analysis of helicopter rotors operating in ground effect. Assuming the ground to be a purely reflective flat surface, the scope is twofold: comparison of different techniques to model its presence and assessment of its effects on the emitted noise field. To this purpose, the mirror image method is applied to evaluate the influence of the ground on the aerodynamic sound sources distributed over the rotor blades (indirect acoustic effect), whereas a noise scattering formulation is used to determine its effects as a sound reflecting surface impinged by the pressure field radiated by the rotor (direct acoustic effect). The numerical investigations examine the impact of the rotor height above the ground both on near and far field noise, and provide highlights on potentialities and drawbacks of the different modeling approaches considered.
Pasquali, C., Poggi, C., Bernardini, G., Serafini, J., Gennaretti, M. (2019). Aeroacoustic Analysis of Helicopter Rotors in Ground Effect. In Proceedings of 25th AIAA/CEAS Aeroacoustics Conference [10.2514/6.2019-2616].
Aeroacoustic Analysis of Helicopter Rotors in Ground Effect
Pasquali C.;Poggi C.;Bernardini G.;Serafini J.;Gennaretti M.
2019-01-01
Abstract
This paper deals with the aeroacoustic analysis of helicopter rotors operating in ground effect. Assuming the ground to be a purely reflective flat surface, the scope is twofold: comparison of different techniques to model its presence and assessment of its effects on the emitted noise field. To this purpose, the mirror image method is applied to evaluate the influence of the ground on the aerodynamic sound sources distributed over the rotor blades (indirect acoustic effect), whereas a noise scattering formulation is used to determine its effects as a sound reflecting surface impinged by the pressure field radiated by the rotor (direct acoustic effect). The numerical investigations examine the impact of the rotor height above the ground both on near and far field noise, and provide highlights on potentialities and drawbacks of the different modeling approaches considered.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.