Aeroacoustic Flight Test and Data Analysis for the Validation of Fenestron Noise Computations

The Fenestron Noise Study, done in partnership by ONERA, Eurocopter and DGA Flight Test, focuses on the noise radiated by a Fenestron shrouded tail rotor depending on the flight conditions. This study combines test measurements, numerical simulations and has two main objectives: first to enhance the comprehension of the noise generation mechanisms involved in a shrouded tail rotor, secondly to validate the numerical tools developed at ONERA for the calculation and prediction of helicopter aerodynamics and aeroacoustics. This paper presents the experimental setup, the flight tests and the data processing method dedicated to the validation of the simulation tools. The second part of the paper describes the simulation tools used for aerodynamic and aeroacoustic predictions of a Fenestron tail rotor. Finally, preliminary comparisons between experiments and calculations are shown for a level flight at speed 150 kts.