Aeroacoustic investigations of a generic fan-in-wing configuration

Noise generated by unsteady turbulent flows around aerodynamic bodies continues to pose a challenge to aeronautical engineers. Accurate and detailed prediction of noise sources is essential in order to control or modify them to comply with noise regulations. In this paper, a combination of experimental and numerical investigations is carried out to understand the noise-generation mechanisms for a generic fan-in-wing configuration which is relevant to Vertical and Short-Take-Off and Landing aircraft designs or encapsulated tail rotors. A structured mesh with minimum simplifications has been generated and a sliding mesh has been used to model the fan rotation. Steady and Unsteady Reynolds Averaged Navier-Stokes computations are performed using the shear stress transport turbulence model. The obtained unsteady flow data have been post processed to extract the radiated sound pressure field in the near- as well as in the far-field. To compute the acoustic far-field, the Ffowcs-Williams Hawkings surface integral formulation has been adopted. The variation of Sound Pressure Level at different observer locations is compared to experimental data. For the first and second harmonics, a good agreement has been found in terms of sound pressure level and frequency distribution.