Aeroacoustics analysis of 2D UAV wing at different flap deflections and incorporation of bio inspired aeroacoustics reduction techniques

The military use of unmanned aerial vehicle is on the rise due to their capability of performing surveillance, reconnaissance and in some cases, combat missions by keeping their human operators at a safe distance. The successful completion of missions performed by UAVs over hostile territories also depend upon their acoustic signature. The main source of acoustic generation by the UAV is undoubtedly their propulsion systems, however at slow speeds, the noise generated due to the interaction of the airflow and the UAV structure, known as aeroacoustics, also becomes dominant contributor in the overall acoustic signature of UAV. In this research work, the aeroacoustic analysis of a 2D airfoil of an in-service military UAV wing is carried out. The flow is simulated using Large Eddy Simulation turbulence modelling technique and to evaluate the acoustics level at the designated receiver location, FW-H model analogy is utilized in the Ansys Fluent® environment. The analysis is focused on the effect of varying flap deflections over the sound pressure level at the receiver location. The effect of these variations on aerodynamic characteristics and aeroacoustics generation is analyzed and discussed in details. The bioinspired aeroacoustics reduction techniques are then implemented on the subject UAV wing to analyze its efficacy keeping the aerodynamic characteristics of the wing unaltered.